# Ecosystem-based assessment of a widespread Mediterranean marine habitat: The Coastal Detrital Bottoms, with a special focus on epibenthic assemblages

Patrick Astruch, Ameline Orts, Thomas Schohn, Bruno Belloni, Enric

Ballesteros, Daniela Bănaru, Carlo Nike Bianchi, Charles-François

Boudouresque, Thomas Changeux, Pierre Chevaldonné, et al.

► To cite this version:

Patrick Astruch, Ameline Orts, Thomas Schohn, Bruno Belloni, Enric Ballesteros, et al.. Ecosystem-based assessment of a widespread Mediterranean marine habitat: The Coastal Detrital Bottoms, with a special focus on epibenthic assemblages. Frontiers in Marine Science, 2023, 10, pp.1130540. 10.3389/fmars.2023.1130540. hal-04187007

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https://amu.hal.science/hal-04187007v1

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# Ecosystem-based assessment of a widespread Mediterranean marine habitat: the Coastal Detrital Bottoms, with a special focus on epibenthic assemblages

1 Patrick Astruch¹*, Ameline Orts¹, Thomas Schohn¹, Bruno Belloni¹, Enrique Ballesteros²,

2 Daniela Bănaru³, Carlo Nike Bianchi⁴,⁵, Charles-François Boudouresque³, Pierre

3 Chevaldonné⁶, Jean-Georges Harmelin¹, Noëmie Michez⁷,⁸, Briac Monnier⁹, Carla Morri⁴,⁵,

4 Thierry Thibaut³, Marc Verlaque³, Boris Daniel†⁸

5 ¹GIS Posidonie, Aix-Marseille Université, Mediterranean Institute of Oceanography (MIO),

6 Marseille, France

7 ²CEAB-CSIC, 17300 Blanes, Girona, Spain

8 ³Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of

9 Oceanography (MIO), Marseille, France

10 ⁴Seascape Ecology Laboratory, DiSTAV (Department of Earth, Environment and Life Sciences),

11 University of Genoa, Genova, Italy

12 ⁵EMI, Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn-National,

13 Institute of Marine Biology, Ecology and Biotechnology, Genoa Marine Centre, Genoa, Italy

14 ⁶IMBE, CNRS, IRD, Aix-Marseille University, Avignon University, Station Marine d'Endoume,

15 Marseille, France

16 ⁷Parc naturel Marin du Golfe du Lion, Argelès-sur-mer, France

17 ⁸Office Français de la Biodiversité, Brest, France

18 ⁹ Université de Corse Pasquale Paoli, CNRS UMR 6134 SPE, Campus Grimaldi, Corte, France

19 * Correspondence: Patrick Astruch

20 patrick.astruch@univ-amu.fr

21 Key words: Coastal Detrital Bottoms, Ecosystem-based approach, Quality assessment, Marine

22 Habitat, Rhodolith beds, Epibenthic assemblages, Mediterranean Sea

23 Written in British English

24 6 tables

25 9 Figures

26 1 Supplementary Table

27 1 Supplementary Figure
28 **Abstract**

29 Coastal detrital bottoms (CDB) are one of the most extensive habitats of the continental shelf
30 worldwide, in the upper levels of the circalittoral zone. Hosting a diverse community structured by
31 sediment grain size, trophic interactions and rhodoliths, bryozoans and other calcified organisms, CDB
32 play important ecological functions. In the Mediterranean Sea, CDB are constituted by recent elements
33 partly provided by adjacent infralittoral (e.g., rocky reefs and *Posidonia oceanica* meadows) and
34 circalittoral (e.g., coralligenous reefs) ecosystems. Since the 2010s, the offshore extension of many
35 Marine Protected Areas (MPAs) has substantially incorporated vast areas of CDB, and at the same time
36 raised the issue of their management. Until recently, studies focused on CDB have mainly dealt with
37 infauna, taxonomy and rhodolith beds, while very few have considered global functional aspects.
38 European Directives such as the Habitats Directive (HD), the Water Framework Directive (WFD) and
39 the Marine Strategy Framework Directive (MSFD) aim at maintaining or improving the ecological
40 status (ES) or conservation status of water bodies and habitats. The MSFD has embraced the concept
41 of an ecosystem-based approach to consider the functioning of marine habitats and their related
42 ecosystem services provided as new indices for managers. The purpose of this paper is to propose an
43 ecosystem-based quality index (EBQI) tested on CDB from the north-western Mediterranean Sea,
44 focusing mainly on epibenthic assemblages. The first step has been to define a conceptual model of the
45 CDB functioning, including the main trophic compartments and their relative weight, then to identify
46 appropriate assessment methods and potential descriptors. Twenty-nine sites were sampled along the
47 coast of Provence and French Riviera (South France) with SCUBA diving and a purposely designed
48 device, the ‘Biocube’. Study sites were chosen in order to encompass a wide range of hydrological
49 conditions and human pressures. We observed very different ES driven by local natural features and
50 human activities. Very well-preserved sites were found in Provence in areas without trawling and
51 terrigenous inputs, while impacted and low-ES sites were located in the vicinity of urbanized areas.
52 The cover of Corallinales, Peysonneliales and Sporolithales qualifies the seascape and might be an
53 indicator of the good ecological status of CDB and reduced human pressure. However, the absence of
54 rhodolith association may also be induced by natural phenomena. The EBQI designed for CDB proved
55 representative and useful for a functional assessment based on epibenthic assemblages. Robustness of
56 status and weighting of the compartments were tested. However, some descriptors have shown their
57 limitations and should be further explored for a proper assessment, bearing in mind that effective
58 indices should be quick and easy to apply. We highlight here the issue of establishing an index
59 corresponding to a societal demand (e.g., European directives, Barcelona convention) to lead to a broad
60 and large-scale assessment based mainly on the seascape and epibenthic assemblages, for practical and
61 operational reasons. We stress the need to extend this index over a wider geographical scale,
62 particularly to the southern and eastern Mediterranean Sea sectors, which are highly affected by the
63 spread of non-indigenous species. The applicability of this index to extra-Mediterranean locations
64 should also be considered.

65 **1 Introduction**

66 Coastal detrital bottoms (CDB), sometimes also called coastal (bio-)detritic bottoms in the literature,
67 are soft bottoms composed of mineral and biogenic particles, characterized by a distinct structural
68 complexity hosting soft sediment infauna together with epifauna and epiflora settled or not on coarser
69 granules (Rees, 1999). Often regarded in the past as an inconvenient mixture escaping the classical
70 dichotomy between rock and sediment biotopes (Jones, 1950), they are today considered as a
71 distinctive biotope in the circalittoral zone of the continental shelf worldwide (Pérès, 1982; Konar et
72 al., 2006; Amado-Filho and Pereira Filho, 2012; La Rivière et al., 2021).
In the Mediterranean Sea, CDB are one of the most widespread ecosystems between 30 and 100 m depth, corresponding to the upper part of the circalittoral zone (Pérès and Picard, 1964; Pérès, 1967), and house a high alpha species diversity (Stamouli et al., 2022). Besides a mineral component (typically coarse sand with a variable proportion of finer particles), these bottoms contain significant quantities of recent organogenic and bioclastic sediments (remains from hard bottoms, shell debris, bryozoans or calcified macro-algae), either autogenous or imported from adjacent ecosystems (e.g., coralligenous reefs, photophilic rocky reefs, seagrass meadows). Structure and composition of CDB can therefore differ depending on adjacent ecosystems and hydrodynamic conditions (Pérès and Picard, 1964; Joher et al., 2015; Agnesi et al., 2020). The pelitic proportion (sediment grain < 63 µm) of the sediment is usually very low, but muddy CDB can be found (Bellan-Santini et al., 1994). Located at the same depth range than CDB, Muddy Detrital Bottoms (MDB) are characterized by an important sedimentation rate influenced by the terrigenous input from coastal rivers. MDB can be constituted by a compact mud including bioclastic shells, muddy sand, or sandy mud (Pérès and Picard, 1964; Picard, 1965; Bellan-Santini et al., 1994; Michez et al., 2014; La Rivière et al., 2021). Deep Detrital Bottoms (DDB), generally between 80 and 250 m depth, correspond to fossilized detrital sediments from terrigenous (fluviatile) and bioclastic inputs corresponding to ancient environmental conditions and a lower sea level (Pérès and Picard, 1964; Bellan-Santini et al., 1994), covering the deepest part of the continental shelf. The sediment is a mix of pebbles, sand and mud but with a mud proportion significantly higher than in the CDB. Coarser sediment is made of calcareous remains from thanatocenoses of the Pleistocene ice ages (Laborel et al., 1961; Pérès and Picard, 1964; Bourcier and Zibrowius, 1973; Michez et al., 2011, 2014). Distinguishing the boundary between CDB and muddy or deep detrital ecosystems is sometime challenging.

Pérès and Picard (1964) based their description of CDB on the infauna, which contain the most characteristic species; however, the same authors and others (Costa, 1960; Joher et al., 2015; La Rivière et al., 2021) identified a number of CDB facies on the basis of less characteristic epibenthic species, especially macroalgae, either erect or encrusting. The former include perennial and seasonal species, such as *Cystoseira* spp., *Ericaria* spp., *Gongolaria* spp., *Osmundaria volubilis*, etc.; the latter are represented by the Corallinales *Lithophyllum racemus*, *Lithothamnion corallioides*, *L. crispatum*, *L. minervae*, *L. valens*, *Neogoniolithon hauckii*, *Spongites fruticulosa*, the Peyssonneliales *Peyssonnelia crispata*, *P. heteromorpha*, *P. rosa-marina*, *P. rubra*, *P. squamaria*, and the Sporolithales *Sporolithon mediterranea*, among others (Huvé, 1954; Jacquotte, 1962; Boudouresque and Denizot, 1973; Ballesteros, 1994). Free-living calcified macroalgae forming nodules of various morphology, called “rhodoliths” (or more specifically “maerl” in the case of branched growth forms), raised a great interest among benthic ecologists (Sciberras et al., 2009; Basso et al., 2017; Deidun et al., 2022). Their conservation value is recognized under EU rules and international conventions (Barbera et al. 2003; Salomidi et al., 2012). Marion (1883), Meinesz et al. (1983) and Holon and Harmelin (2014) described a CDB facies with large calcified bryozoans, such as *Pentapora fascialis*, *Smittina cervicornis*, *Turbicellepora avicularis*, *Hornera* spp., etc. But the highest diversity of bryozoans on CDB is represented by numerous ans small species (Harmelin, 2017); by analogy with calcareous rhodophytes, bryozoan free are called bryoliths (James et al., 2006; Lombardi et al., 2014). This bryozoan facies is classified as a priority habitat according to the Barcelona Convention (Bianchi, 2009a). Recently, coralliths formed by the scleractinian coral *Cladocora caespitosa*, also considered of conservation interest (Morri et al., 2000; Bianchi, 2009b), have been described from coarse sandy bottoms in the Balearic Islands (Kersting et al., 2017a, 2017b). Several octocoral species, such as *Eunicella singularis*, *E. verrucosa*, *Leptogorgia sarmentosa*, *Alcyonium palmatum*, *Pennatula rubra*, *Pteroeides griseum* and others, may also form epibenthic facies on detrital seabeds (Morri et al., 1991). Fauna and flora associated to all these epibenthic facies are sometimes very similar to coralligenous assemblages (Ballesteros, 2006; Pergent et al., 2015). The EUNIS typology defines Coralligenous platforms These
121 are coralligenous horizontal formations developing within sedimentary beds subject to currents, at up
to at least 100 metres depth in clear waters. These formations are not usually built on rock substrata
122 but result from the active development of constructor organisms (e.g. calcified algae, hard-skeleton
123 invertebrates) from scattered elements on loose beds, shells, stones, and graves (Pérès and Picard,
124 1965).
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126 Important ecological functions and ecosystem services, up to now poorly-evaluated, are provided by
127 CDB (Ballesteros, 1994; Barbera et al., 2003): (i) primary production (Basso, 2012; Basso et al., 2012),
128 (ii) key habitat and trophic resources for invertebrates and fish, (iii) breeding, spawning and nursery
129 grounds for fish and crustaceans including species of fishery interest, sometimes close to the deep limit
130 of *Posidonia oceanica* meadow (e.g., Mullidae, Sparidae, Scorpaenidae, *Palinurus elephas*) (Harmelin
131 and Harmelin-Vivien, 1976; Verlaque, 1990; Kamenos et al., 2004; Soykan et al., 2010), (iv) fishing
132 ground for trawlers and artisanal fishers (Stamouli et al., 2022), (v) long term carbon sink (Basso, 2012;
133 Basso et al., 2012; Savini et al., 2012; Burrows et al., 2014; Watanabe et al., 2020), (vi) recycling of
134 necromass (e. g. rhizomes and dead *Posidonia oceanica* leaves and drift macroalgae) (Boudouresque
135 et al., 2016). In addition, CDB host numerous protected species and other species of conservation
136 interest (Astruch et al., 2012, 2019; Joher et al., 2015): the fan shell *Pinna nobilis* (annexe II Berne
137 convention and UICN Red list: critically endangered), the red coralline alga *Lithothamnion
corallioides* (Annexe 5 of the HD: species of interest with a regulation of its exploitation), and several
138 Fucales (Annexe 2 of the Barcelona convention), among others. Management goals on maerl beds are
139 different in the Mediterranean compared to the rest of the world, where extraction activities are carried
140 out (Foster et al., 1997, 2013; Steller et al., 2003; Amado-Filho et al., 2017; Harvey et al., 2017).
141

142 Nowadays, like most coastal biocenoses, CDB are facing human activities and climate change. They
143 are threatened by numerous pressures (Dutertre et al., 2015; Demestre et al., 2017) such as trawling
144 (Bordehore et al., 2000, 2003; Fragkopoulou et al., 2021), artisanal or recreational fishing (Rendina et
145 al., 2020), dredging (De Grave and Whitaker, 1999; Bermejo et al., 2018; Bernard et al., 2019),
146 terrigenous input, dumping of sediment and waste, fish farming (Sanz-Lázaro et al., 2011; Aguado-
147 Giménez and Ruiz-Fernández, 2012), consequences of coastal development, sea water warming,
148 spread of non-indigenous species (Klein and Verlaque, 2009; Katsanevakis et al., 2014; Martin and
149 Hall-Spencer, 2017; Hall-Spencer and Harvey, 2019) and potentially acidification (Noisette et al.,
150 2013).
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151 Until recently, studies about CDB in the Mediterranean Sea were mainly focused on description of
152 infauna (e.g., Pérès and Picard, 1964; Picard, 1965; Somaschini et al., 1998), rhodolith beds and
153 associated communities (e.g., Ballesteros, 1994; Basso et al., 2017), and taxonomy (e.g., Boudouresque
154 and Denizot, 1973; Souto et al., 2010), without any overview at ecosystem scale (e.g., Gautier and
155 Picard, 1957; Jacquotte, 1962; Boudouresque and Denizot, 1973; Augier and Boudouresque, 1975,
156 1978; Laborel et al., 1976; Harmelin, 1978; Bourcier, 1982, 1985, 1988; Fornos et al., 1988; Joher et
157 al., 2012, 2015).
158

158 Despite the high ecological and heritage value of CDB and the many threats pending on it, this
159 ecosystem was not considered as a habitat of European interest (Bensettiti et al., 2004) by the Habitats
160 Directive of the European Union (Natura 2000, 92/43/CEE) while some facies of CDB are described
161 in EUNIS typology (Gayet et al., 2018) and considered in Barcelona convention. Recently, the Habitats
162 Directive has evolved, considering rhodolith beds as a reef habitat (1170) if it host communities
163 characteristic of hard substrates (De Bettignies et al., 2021). In France, the extension of surface areas
164 of Marine Protected Area (MPA) (national parks, Natura 2000 sites, etc.), since the 2010s, incorporated
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large expanses of seabed occupied by CDB. According to these new management issues, it has become
a challenge to better consider this widespread ecosystem.

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Even with the improving accuracy of technologies (e.g., side scan sonar, multibeam, remotely operated vehicles, autonomous underwater vehicles, etc.) (Bianchi et al., 2004; Astruch et al., 2012; Valette-Sansevin et al., 2019) and prediction models (Martin et al., 2014; Vassallo et al., 2018), mapping of CDB is still challenging. The evaluation of coastal water body masses, marine habitats or ecosystems involves numerous indices with different purposes (Bianchi et al., 2022). None of these indices is able to solve all issues: specific descriptors may assess the ecological status linked with water quality (WFD; e.g., Ballesteros et al., 2007; Gobert et al., 2009; Lopez y Royo et al., 2010; Blanfuné et al., 2017; Piazzi et al., 2021), ecosystem functioning (descriptor 1 of the MSFD; e.g., Personnic et al., 2014; Giakoumi et al., 2015; Montefalcone et al., 2015a), seafloor integrity (descriptor 6 of the MSFD; e.g., Montefalcone et al., 2007; Gatti et al., 2015; Enrichetti et al., 2019; Piazzi et al., 2019), the conservation status of natural habitats (HD; e.g., Maciejewski et al., 2016; Sartoretto et al., 2017), natural and anthropogenic stressors (Holon et al., 2015; La Rivière et al., 2017; Ruitton et al., 2020).

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Obviously, the future of coastal zone management is not linked with a unique integrative index (Bond, 2001), but a consistent combination of the more relevant ones (Pikaver et al., 2004; Paoli et al., 2016; Borja et al., 2021; Oprandi et al., 2021). Indicators are currently used to support managers and stakeholders' guidelines. In that context, the ecosystem-based approach is to be considered (Laffoley et al., 2004; Boudouresque et al., 2020a), aiming at a better understanding of ecosystem functioning for a more suitable management. Ecosystem-Based Quality Indices (EBQIs) have been already defined for a number of coastal marine ecosystems, namely *Posidonia oceanica* meadows (Personnic et al., 2014), coralligenous reefs (Ruitton et al., 2014), undersea caves (Rastorgueff et al., 2015) and rocky reefs (Thibaut et al., 2017). The aim of the present work is to develop and apply an original EBQI expressly designed for CDB (Astruch et al., 2021). Although CDB is traditionally identified mostly by the study of the infaunal component, which requires sampling with grabs or dredges operated from large vessels, the approach presented here will focus on the epibenthic component, which can be studied with a light-duty approach, i. e. photo, video and/or visual techniques - to be privileged in a conservation context (Bianchi et al., 2022). The adequacy of this novel index was tested along the coasts of Provence and French Riviera (France, Mediterranean Sea) (Fig. 2).

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## 2 Material and Methods

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### 2.1 Conceptual model of Coastal Detrital Bottom functioning

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A workshop gathering 15 experts in benthic ecology (mainly authors of the present work) was held (i) to propose and validate a conceptual model of the CDB functioning, (ii) to define the weight of each functional compartment (=box) corresponding to its importance in the ecosystem, and (iii) to elaborate a sampling protocol with suitable and operational descriptors to assess the different compartments. A DELPHI approach was carried out (Rowe and Wright, 1999). The conceptual model thus defined schematizes the functioning of CDB (Fig. 1). The compartments of the conceptual model are described in the following pages.

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### 2.2 Sampling strategy

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Twenty-nine sampling sites were investigated (Table 1). Site selection considered different level of pressures linked with human activities, from pristine-like to urbanized sites. The study area presents a gradient in hydrological conditions, involving the Rhône River at the West, the oligotrophic waters of eastern Provence and the run-offs in the urbanized French Riviera.
208 Two depth ranges were sampled at each site: the upper zone (between 28 and 43 m, according to the
209 lower limit of the *Posidonia oceanica* meadow), and the deep zone (between 48 and 79 m depth).
210 Upper sites were selected far enough away from *P. oceanica* meadows to avoid the transitional zone
211 and ensure a correct assessment of CDB compartments.

212 Sampling was carried out by scuba diving, photoquadrats and seascape video. At the upper zone,
213 observations were carried out by scuba divers for inventory of *in situ* recognizable taxa and assessment
214 of their abundance. Each dive corresponds to the observation of 2 divers during ~12 minutes.
215 Considering the movements of the divers at an average speed of 10 m·min⁻¹ (including stops) observing
216 the bottom on a 2 m wide strip, each dive corresponds to an investigated surface area of ~500 m². Three
217 cores of sediment were sampled per site to assess organic matter and sediment grain size. At both upper
218 and deep zone, an original device, the ‘Biocube’ (Fig. 3), was implemented to sample: (i) photoquadrats
219 of an 80 cm × 80 cm sized frame using a compact camera with a 15 s time lapse. On-board video
220 monitoring using a GoPro® Hero 3 allowed controlling the position of the quadrat during sampling.
221 Each quadrat was randomly positioned according to the drift of the operating boat. (ii) Seascape videos
222 were taken during the photoquadrat sampling. The diversity of sampling methods aims at bringing
223 complementary observations at the scale of each sampling site for a standardized assessment.

224 **2.3 Compartments assessed**

225 **2.3.1 Box 1: Rhodoliths: Free living Corallinales, Peyssonneliales, and Sporolithales**

226 This compartment is involved in the structuring of the ecosystem by increasing sediment grain size and
227 providing a support for other compartments (see boxes 2, 3, 10 in Fig. 1). Among Corallinales, several
228 species can be found such as *Lithothamnion corallioides*. Peyssonneliales can be calcareous or not,
229 several species occur in CDB, such as *Peyssonnelia rosa-marina* (Boudouresque and Denizot, 1973)
230 or *P. squamaria*. The Sporolithale *Sporolithon mediterraneum* is a frequent rhodolith species of CDB.
231 For some species, *in situ* identification is challenging or impossible and collection is needed. The cover
232 is naturally decreasing according to depth and the corresponding reduction of light availability. In
233 oligotrophic and clear waters, rhodolith beds can found up to 80 m depth (Ballesteros, 1994). Aguilar
234 et al. (2009) described rhodolith beds at 140-150 m depth around the Balearic Islands. Rhodoliths play
235 an important role in the deep benthic fixing and sequestration of organic and inorganic carbon (Basso,
236 2012; Basso et al., 2016). The cover (mean percentage) of living rhodoliths appears to be the easiest
237 descriptor to assess the structure of CDB, which conditions its functioning both at the upper and the
238 deep zones (Bosellini and Ginsburg, 1971; Basso et al., 2016).

239 **2.3.2 Box 2: Perennial non-calcified macroalgae**

240 The abundance of perennial non-calcified macroalgae can be linked to good ecological conditions and
241 the absence of significant pressures (mechanical erosion, terrigenous inputs, decrease of light). Fucales
242 (*Sargassum* spp., *Ericaria* spp., *Gongolaria* spp., *Cystoseira* spp.), Laminariales (*Laminaria rodriguezii*), *Osmundaria volubilis* and *Carpomitra costata* are among the most representative taxa
243 (Gautier and Picard, 1957; Joher et al., 2012; Thibaut et al., 2016; Jouissi et al., 2018; Bermejo et al.,
244 2018; Bruno de Sousa et al., 2019; Jódar-Pérez et al., 2020; Reynes et al., 2021). These long-living
245 species provide a stand for seasonal macroalgae (boxes 3 and 4) and sessile fauna (box 10), a habitat
246 (boxes 9 and 12) and a trophic resource (box 5). They contribute significantly to the primary production
247 of the ecosystem. *Codium bursa*, *C. vermilara*, and *Sphaerococcus coronopifolius*, perennial species
248 observed during the present work, were not considered. Indeed, the abundance of these species known
249 as tolerant can be linked to a stressor (Vidondo and Duarte, 1995; Ruitton et al., 2017). In addition, C.
250
fragile is a non-indigenous species (Provan et al., 2005). The mean percentage cover at the upper zone is a suitable descriptor to assess this compartment.

### 2.3.3 Box 3: Seasonal erected macroalgae

Macroalgae species from this compartment, characterized by fast growth rate and seasonal cycle, thrive mainly from spring for a maximum development during summer. Seasonal macroalgae also contribute significantly to primary production. The most frequent and abundant taxa are the Phaeophyceae *Arthrocladia villosa* and *Sporochnus pedunculatus*, widespread in the circalittoral both in Coralligenous reefs and CDB. Some species usually observed in the infralittoral can be found such as *Acetabularia acetabulum* or *Padina pavonica*. *Umbraulva dangeardii* is a Ulvophycea that can be observed often associated with rhodolith beds. *Chrysymenia ventricosa* and *Sebdenia* spp. are among the main characteristic Florideophyceae. Identification at species level is impossible based on *in situ* observation and video and photographs analysis. The mean cover (percentage) of seasonal macroalgae appears to be a suitable descriptor. Non-indigenous and invasive species with a seasonal dynamic can thrive in the CDB: *Caulerpa cylindracea* (Klein and Verlaque, 2008), *C. taxifolia* (Meinesz et al., 2001; Montefalcone et al., 2015b), mucilage (several species including NIS: *Acinetospora crinita*, *Chrysonephos lewisii*, *Nematochrysopsis marina*, *Zosterocarpus oedogonium*) (Giuliani et al., 2005; Schiaparelli et al., 2007; Bianchi et al., 2019a). The latter taxa have been considered as stressors and therefore not taken into account in the assessment of compartment 3.

### 2.3.4 Box 4: Seasonal turf

Seasonal turf is defined as an algal community with a small height (a few centimetres at most). Worldwide, turf is more and more observed replacing more structuring communities, influenced by stressors (Littler and Littler, 1980; Connell et al., 2014). Seasonal turfs include numerous species but very few can be identified *in situ* like the Ulvophyceae *Pseudochlorodesmis furcellata* and *Valonia macrophysa*. *Womersleyella setacea* and *Acrothamnion preissii*, two alien species (Boudouresque and Verlaque, 2002), can be present and are considered as stressors. These two species are often invasive in coralligenous reefs, *Posidonia oceanica* meadows, and infralittoral photophilic reefs (Piazzi and Cinelli, 2000; Piazzi et al., 2007; Bianchi et al., 2019b), and were found in CDB of Port-Cros National Park (Provence, France; Astruch et al., 2019). The distinction by visual assessment between seasonal turf and seasonal erected macroalgae is difficult. Considering that the two compartments evolve with the same dynamics, it is relevant to consider their cumulative cover as the descriptor of their status at both upper and deep zones. The 'compartments 3 and 4' are therefore named hereafter 'compartment 3-4'.

### 2.3.5 Box 5: Herbivores

The important diversity of the macroalgal communities on CDB (boxes 1, 2, 3, 4) influences the abundance and the diversity of herbivores. In the present work, the following taxa were considered as herbivores: echinids (*Centrostephanus longispinus*, *Echinus melo*, *Sphaerechinus granularis*, *Stylocidaris affinis*), and the gastropods *Cerithium* sp. and *Aplysia* spp. While *S. granularis* is strictly an herbivore (Weinberg, 1996; Wirtz and Debelius, 2003), *S. affinis*, *C. longispinus* and *E. melo* are omnivores. The latter two are not characteristic of CDB, even if they can be found in the vicinity of coralligenous beds. According to food availability and habitat (Wilkie et al., 1996), they are able to shift into an herbivorous-dominant behaviour (De Ridder and Lawrence, 1982; Francour, 1989, 1991; Bergbauer and Humberg, 2000). *S. granularis* and *S. affinis* are known to be seasonally observed gathering on detrital bottoms (Harmelin and Duval, 1983). Vertebrate herbivores are mainly represented seasonally by the fish *Sarpa salpa* during its breeding period (late summer) (Verlaque, 1990). Considering the short duration of the phenomenon, this species is not taken into account in this
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compartment. The alpha taxonomic richness (number of taxa per site) is a relevant descriptor to assess
the herbivores compartment.

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2.3.6 Box 6: Particulate Organic Matter of the sediment (POM)

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Particulate organic matter (POM) of the sediment observed in abundance can be linked to natural eutrophic conditions or to a stressor (Sciberras et al., 2009). Based on our sampling strategy, the assessment of this compartment is feasible by considering the cover of muddy sediment on the bottom observed on the photoquadrats. This descriptor is already applied to assess the POM sedimented on coralligenous reefs (Ruitton et al., 2017). However, its assessment on CDB proved difficult. We therefore propose the percentage of pelitic fraction (<63 µm) as a proxy of the POM of the sediment. Organic matter accumulation is determined by environmental dynamics (currents, fine particles transfer to deep areas) (Orekhova and Ovsyany, 2020). An important percentage can also correspond to Muddy Detrital Bottoms (MDB).

308

2.3.7 Box 7: Infauna

309
310

Infauna constitutes a key compartment, influenced by sediment grain size and organic matter content (Pérès and Picard, 1964; Cocito et al., 1990). We distinguished three trophic groups within the infauna:

311
312
313
314
315
316
317
318
319
320

CDB, particularly in the upper circalittoral zone, are characterized by a relatively coarse grain size, decreasing with depth. It directly influences the trophic network in the sediment. Consequently, coarse sediment hosts a lower content in organic matter and a lower abundance of the infauna (Blanchard et al., 2009). According to Bellan et al. (1980), high organic matter content can be a stressor for infauna, traducing a blocking of the recycling of organic matter by polluted water inputs. The organic matter content is often used as a descriptor of the trophic status of infauna (Cocito et al., 1990; Dell'Anno et al., 2002). However, natural abundance of organic matter can be linked to the vicinity of seagrass meadows, (i) providing dead leaves that partly remain in the sediment, or (ii) with dead matter a few cm under the sediment surface (Boudouresque et al., 2019). In the present work, we evaluate the whole infauna compartment from the organic matter content in the sediment (percentage).

321

2.3.8 Box 8: Organic microdetritus

322
323
324
325
326
327

*Posidonia oceanica* seagrass meadows produce and export a huge number of dead leaves to adjacent ecosystems, including CDB (Boudouresque et al., 2016). Infralittoral photophilous reefs and coralligenous reefs also export macroalgae, which accumulate or move over circalittoral soft bottoms. Organic macrodetritus composition and biomass vary according to source ecosystems: dead leaves of *P. oceanica*, macroalgae or terrestrial plant remains. Before reaching greater depth, off the continental shelf, organic macrodetritus is used as a trophic resource by the detritivores of the CDB.

328

2.3.9 Box 9: Detritivores

329
330
331
332
333
334
335
336

Detritivores play an important role, degrading litter and organic debris on the sediment. This compartment is composed of Echinodermata (Holothuroidea, Echinoidea and Asteroidea), Crustacea and Gastropoda. The abundance of some taxa can be favoured by eutrophic (i.e., HOM: High Organic Matter) or oligotrophic (LOM: Low Organic Matter) conditions. Two categories are distinguished: **(9a) HOM Detritivores:** including *Holothuria* spp., *Bonellia viridis* and Paguridea; **(9b) LOM Detritivores:** represented by *Spatangus purpureus*, *Echinaster sepositus*, Gastropoda and Crustacea (Mysidacea, Malacostraca). While a high abundance of HOM detritivores can be linked with a CDB potentially degraded (eutrophication), the abundance of LOM detritivores, more sensitive to
337 eutrophication, indicates a good status of this compartment. Mean density (individuals per m² observed
338 in the photoquadrats at both depth) is a relevant descriptor to assess detritivores 9a and 9b.

339 **2.3.10 Box 10: Filter and Suspension feeders**

340 Benthic filter and suspension feeders on CDB belong to various taxonomic groups: Annelida,
341 Ascidiacea, Bryozoa, Cnidaria, Porifera) (Harmelin, 1978; Souto et al., 2010). On coralligenous reefs,
342 the abundance of *Cliona viridis* is considered as a consequence of stressors (bioerosion in a eutrophic
343 configuration) (Cerrano et al., 2001), the presence of *C. viridis* with a relatively low density on CDB,
344 as observed in our case study, cannot be considered as an indicator of stress. Mean density of
345 individuals or colonies per m² (observed in the photoquadrats at both depths) seems to be the most
346 suitable descriptor for filter and suspension feeder assessment, unlike taxonomic richness, due to the
347 problems for *in situ* identification or from videos or photographs.

348 **2.3.11 Box 11: Planktivorous teleosts**

349 This compartment includes planktivorous pelagic or demersal fish, with life traits significantly linked
350 with the substrate. Strictly pelagic planktivorous teleosts with no interaction with the bottom (e.g.,
351 Clupeidae, Engraulidae) were not considered. The main species observed were *Spicara maena*, *S.
352 smaris*, *Boops boops*, *Chromis chromis* and *Anthias anthias*. The two latter indicate clearly the vicinity
353 of hard substrates. CDB play an important role for these species: a spawning ground for *Spicara* spp.
354 (Harmelin and Harmelin-Vivien, 1976) and an essential habitat for *Boops boops* juveniles.
355 Planktivorous species are also essential in the trophic network providing a food supply for high level
356 predators (Bănaru et al., 2013; Cresson et al., 2020). The alpha specific richness (number of species
357 per site, considering all methods) was measured to assess the planktivorous teleosts' compartment.

358 **2.3.12 Box 12: Carnivores**

359 This box encompasses all carnivorous species, predators of crustaceans, annelids, fish, sponges and
360 other benthic invertebrates. This box is divided in two: Invertebrate carnivores (12a) and Vertebrate
361 carnivores (12b). **(12a) Invertebrate carnivores:** it includes mainly motile species: crustaceans,
362 echinids (Asteroidea, Ophiuroidea), Gastropoda, Nudibranchia, Cnidaria, etc. The alpha taxonomic
363 richness of invertebrates carnivorous (per site considering all methods) is a suitable descriptor for this
364 compartment. **(12b) Vertebrate carnivores:** it gathers teleost fish species (e.g., Pleuronectidae,
365 Trachinidae, Sparidae, Gobiidae, Blenniidae, Mullidae, Labridae, Triglidae) and chondrichthyans (e.g.,
366 *Scyliorhinus* spp., Rajidae). Carnivorous fish find an important trophic resource at the surface or inside
367 the sediment of CDB. Some use CDB as a nursery habitat (e.g., *Serranus hepatus*, *Blennius ocellaris*)
368 or a breeding habitat (e.g., *Symphodus cinereus*, *Solea* spp.). The assessment of abundance or diversity
369 of fish assemblages normally applied in other marine habitats, such as reefs or seagrass meadows
370 (Harmelin-Vivien et al., 1985), proved of little applicability in CDB. The most suitable descriptor to
371 assess the compartment 12b is the alpha taxonomic richness (number of species observed per site
372 considering all methods).

373 **2.4 Compartments not assessed**

374 In the frame of an ecosystem-based approach, it is necessary to considerer all the main functional
375 compartments even if some are not assessed.
376 **2.4.1 Phyto- and Zooplankton**

377 Together with POM, phytoplankton and zooplankton are the basis of planktivores diet (Khoury, 1987;
378 Cresson et al., 2014; Chen et al., 2022). This compartment can vary very quickly, and its proper
379 assessment would require too much time and resources according to its weight in the ecosystem
380 functioning (Table 1). In the framework of an index assessment, the more suitable is to assess it
381 indirectly through its consumers, as done for other ecosystems (see Personnic et al., 2014; Thibaut et
382 al., 2017).

383 **2.4.2 Pelagic Dissolved and Particulate Organic Matter (DOM and POM)**

384 Dissolved organic matter (DOM) and particulate organic matter (POM), provided by phytoplankton
385 exudation, grazing by zooplankton and terrestrial inputs, play a key-role in the marine microbial trophic
386 network (Mostajir et al., 2012) and in some coastal food webs (Darnaude, 2005; Bănaru et al., 2007).
387 As far as the CDB ecosystem is concerned, this compartment is considered as indirectly assessed by
388 the filter feeders and suspension feeders' compartment (Box 10) and therefore was not assessed
389 directly.

390 **2.4.3 Microbial loop**

391 The microbial loop is driven by the DOM and the POM (Velimirov et al., 1984). DOM is an important
392 substrate for bacterial production. The microbial loop is defined as a community gathering
393 heterotrophic micro-organisms, namely Archaea, bacteria, flagellated eukaryotes and ciliates (Azam et
394 al., 1983; Boudouresque, 2015). This compartment is not directly assessed in the present work but it is
395 strictly linked with POM and DOM, plankton communities, filter and suspension feeders (Box 10),
396 planktivores (Box 11) and carnivores (Box 12).

397 **2.4.4 Piscivores**

398 Piscivorous teleosts strictly linked with CDB are very few. High level predators that can be found are
399 mostly casual visitors from adjacent ecosystems (see below). *Lophius* sp. and *Scorpaena scrofa*, two
400 nocturnal and benthic predators, occupy more frequently CDB. At the scale of a given sampling site,
401 the occurrence of piscivores is very low.

402 **2.4.5 Visiting (high-level) predators**

403 Numerous high-level predators can visit occasionally CDB, such as *Dentex dentex*, *Pagrus pagrus*,
404 *Zeus faber*, and feed from planktivorous or mesocarnivorous fish species. Because of a very low and
405 occasional occurrence, this compartment was not taken into account.

406 **2.4.6 Transiting living organisms**

407 Many organisms transit through the CBD mainly from the infralittoral and circalittoral ecosystems to
408 the bathyal and abyssal bottoms. Consequently, numerous species from coralligenous reefs,
409 infralittoral reefs and *Posidonia oceanica* meadows can be found in CDB. The assessment of this
410 transiting fauna was indirect through the main assessed compartments of CDB (Boxes 1, 2, 3-4, 5, 9,
411 10, 12).
### 2.4.7 Carbon sink

Rhodolith beds act as major carbon sinks through their high storage capacity of both organic ($C_{org}$) and inorganic carbon ($C_{inorg}$). The effectiveness of this role is strictly associated with the vitality of calcareous organisms living with these ecosystems (Martin et al., 2007; Basso, 2012; Burrows et al., 2014; Watanabe et al., 2020). While the $C_{inorg}$ sequestration results mainly from the significant calcium carbonate contents of rhodoliths skeleton (Van Der Heijden and Kamenos, 2015), the capture and the trapping of $C_{org}$ within rhodolith beds come from autochthonous and allochthonous sources (Mao et al., 2020). The $C_{org}$ production is mainly completed through the photosynthesis of rhodolith organisms (B1) and the occurrence of facies of calcareous invertebrates (e.g., Bryozoa, Echinidae, Gastropoda, Annelida, Bivalvia). Though the $C_{org}$ fixation is well known for rhodolith beds (Watanabe et al., 2020), its long-term sequestration in the sediments is still to be specified. For *P. oceanica* meadows, the fixation and $C_{org}$ sequestration capacity proved to be highly related with water depth and its state of conservation. Thus, healthy and shallow meadows are considered as carbon sinks whereas deeper and altered ones may act as carbon sources (Monnier, 2020; Monnier et al., 2021, 2022; Pergent-Martini et al., 2021).

## 2.5 Descriptors selection

Fifteen descriptors were selected to assess the 12 boxes of CDB (Table 2). Boxes 3 and 4 were considered together as seasonal macroalgae, so that 11 boxes were actually considered. The weight of each box (W), defined at first during the workshop, was successively adjusted according to the results of the test in the field. The compartments selected to have the main contribution to the functioning of the ecosystem are: Box 1-rhodoliths (W=6), Box 5-infauna (W=5), box 10-filter and suspension feeders, Box 2-perennial and Box 3-4-seasonal macroalgae (W=4).

Descriptors for each compartment were selected among a wide range of available descriptors tested during the sampling. The criteria for the descriptor selection were (i) its applicability, (ii) a large enough range of values along the sampled sites, (iii) the absence of correlations with the descriptors of other compartments in order to reduce the total number of descriptors.

The method to assess each descriptor is presented in Table 3. The monitoring of one sampling site can be held in less than one day with a small boat and 3 operators. It implies (i) one dive with two operators in the upper zone with 12 minutes of investigations (sampling of 3 sediment cores, photographs and videos), covering a mean surface of about 500 m² and (ii) the implementation of the Biocube at the two depths (upper and deep zones) to sample 30 photoquadrats per depth and seascape videos. (iii) Analysis of the cores involves measurement of grain size and percentage of organic matter.

## 2.6 EBQI calculation

The EBQI is then calculated using the following formula:

$$EBQI = \left[ \frac{\sum_{i=1}^{11} (W_i \times S_i)}{\sum_{i=1}^{11} (W_i \times S_{max})} \right] \times 10$$

$W_i$ is the weight of the box, $S_i$ the status of the box and $S_{max}$ maximum status possible (4/4). A notation between 0 and 10 is obtained. An ecological status is defined according to the EBQI notation (Personnic et al., 2014; Table 4). The ecological status limits are similar to those defined for *Posidonia oceanica* seagrass meadow (Personnic et al., 2014), coralligenous reefs (Ruitton et al., 2014) and rocky reefs (Thibaut et al., 2017).
A confidence index (CI) was used to assess the quality of the data (suitable protocol, recent data, expert judgment) (see Personnic et al., 2014 for CI calculation) (Table 5). The CI allows assessing the quality of the sampling according to the recommended methods. If a sampling does not imply all the suitable methods, it will still be possible to calculate an EBQI with a low CI (e.g., data available with other protocols, expert judgement).

## 2.7 Statistical analysis

Correlation between descriptors notation has been tested by calculating Spearman rank-order correlation and assessing its significance with p-value. Principal Component Analysis (PCA) was used without standardization to show relation between boxes and sites EBQI notations.

The robustness of the EBQI for CDB has been tested regarding the ecological status per box and the weight per box. A robustness analysis involving 1000 simulations with 25, 50, 75 or 100% of probability of perturbation of ±1 or ±2 (of each ecological status per box and each weighting per box) has been tested. The analysis recalculates the EBQI notation considering the corresponding perturbation (±1 or ±2) and the probability of perturbation (25, 50, 75 or 100%).

Box status have been plotted on radar charts and the uniformity of box status have been assessed through circularity of polygons representing those charts. Circularity is the ratio between the polygon area and the area of a circle having equal circumference to the polygon perimeter (Oprandi et al., 2021). Perimeter and area have been calculated using ArcGIS Pro 3.0®.

The influence of the management level was tested on EBQI notations and circularity value using PERMANOVA analysis, using euclidian distance and 999 permutations (Anderson, 2001).

P-value threshold was set at 5% for all tests. Analyses were performed with R software (R core team, 2022).

## 474 3 Results

### 475 3.1 EBQI notation

EBQI notation ranged from 2.05 (27TH) to 8.06 (21PAM) (Table 6). Eight sites out of 29 exhibited a Good or Very Good notations while 10 a Poor or Bad status. The Confidence CI was reduced on the box 7 (infauna) for all sites because of the method used (organic matter assessment instead of macrofauna analysis). The CI was very good for all sites, ranging from 88 to 93 %.

EBQI notation and box status attributed to each site are mainly explained by local specificities and the vicinity or not of human activities (i.e., urbanized areas). PCA showed a gradient along Axis 2 (16.8 % of the total variance) from Poor to Very Good sites. Good and Very Good EBQI notations were mainly explained by the high status of boxes 1, 2 and 3-4 (primary producers). Boxes 6 (sedimented POM), 7 (infauna), 8 (organic macrodetritus) and 12 (carnivores) were less discriminating (Fig. 4).

Radar plot projection helps assessing the heterogeneity of ecological status per box for each sampling site (Supplementary Fig. 1). For example, 21PAM (Pampelonne), with the best notation (EBQI = 8.06), is defined by ecological status ranging from 2 to 4 while 09EMB (Embiez), also with a good notation (EBQI = 6.98) is characterized by ecological status between 0 and 4.

A Spearman rank correlation has been tested between the fifteen descriptors used for EBQI calculations (Fig. 5). Positive correlations moderately to highly significant are observed between descriptors related
491 to primary producers (Box 1 - rhodoliths, Box 2 - perennial macroalgae, and Box 3-4: seasonal
492 macroalgae and turf). These same descriptors also show significant correlations with the mean density
493 of LOM detritivores (Box 9b). The diversity of herbivores (Box 5) shows a significant negative
494 correlation with the cover of organic macrodetritus (Box 8). The percentage of organic matter (Box 7)
495 shows low but significant correlations (R² < 0.34) with sedimented POM (Box 6). The percentage of
496 pelitic fraction of the sediment (Box 6) shows a significant negative correlation with the cover of
497 perennial macroalgae (Box 2), rhodoliths (Box 1-UZ) and seasonal macroalgae and turf (Box 3-4).
498 HOM detritivores density (Box 9a) shows no correlations with any other descriptor.

499 **3.2 Circularity analysis**

500 The circularity of radar charts reflects the uniformity of box status. Values range from 0.25 (28ANT)
501 to 0.73 (21PAM) and is independent of the EBQI notation (Spearman correlation: R=0.242 et p=0.206).
502 According to the EBQI notation and circularity value, 4 different situations are identified (Fig. 6): (i)
503 CDB sites with moderate-good notation (EBQI ≥ 5) and high homogeneity of box status (circularity ≥
504 0.5) like 24DRA, 04PLA, 09EMB, 16BAG and 21PAM; (ii) CBD sites with moderate-good notation
505 but low homogeneity of box status like 13FG, 18CAV, 15HB, 20CAM, 26EST, 24PQR and 17 VAI;
506 (iii) CBD sites with poor notation (EBQI < 5) and high homogeneity of box status status like 22ST,
507 10AMP, 07 CC and 29VIL; (iv) CBD sites with poor global notation and low homogeneity of quality
508 status like 27TH, 01COU, 06SUG, 11DF, 05PR, 25AGA, 03PRA, 02CAR, 12TGR, 28ANT, 23SAR
509 and 19CT.

510 **3.3 Influence of the Management level**

511 The management level on the 29 sampling sites is heterogeneous. We can distinguish 4 levels: (i) No
512 protection (4 sites), (ii) Natura 2000 with no effective protection (12 sites), (iii) protected, including
513 MPA with a Multi-Use Management (MUM) (5 sites) (iii) highly protected, including MPA with No-
514 Take Zone (NTZ) (8 sites). Analysis of EBQI mean notation and Circularity mean value per
515 management level shows no significant differences between management level (Permanova:
516 respectively p=0.866 and 0.737; Fig. 7).

517 **3.4 Robustness analysis**

518 **3.4.1 Robustness regarding perturbation of the ecological status**

519 The higher is the perturbation and the probability of perturbation, the less similarity is observed in the
520 iterations compared to the initial EBQI calculation (Fig. 8; Supplementary Table 1). The percentage of
521 similarity decreases with the probability of perturbation or the number of perturbations (±1 or ±2).
522 When perturbing the ecological status per box, the mean similarity (all sites included) evolves from
523 81.8% (25%) to 61.7% (100%) for a ±1 perturbation and from 68.8% (25%) to 38.8% (100%) for a ±2
524 perturbation. A high perturbation of the ecological status implies a lower stability of the EBQI.

525 **3.4.2 Robustness regarding perturbation of the weighting**

526 When perturbing the weighting per box, the mean similarity is higher, moving from 91.5% (25%) to
527 84.5% (100%) for a ±1 perturbation and from 86.5% (25%) to 73.3% (100%) for a ±2 perturbation
528 (Fig. 9; Supplementary Table 1). The perturbation of the weighting does not affect the stability of the
529 index as much as the perturbation of the ecological status per box.

530 The lower values of similarity for high levels of perturbation (±2) of both the ecological status per box
531 and the weighting confirm the fact that weighting the boxes is consistent and useful, as already shown
532 by Personnic et al. (2014) for *Posidonia oceanica* seagrass meadows. It is worth noting that the sites
533 with the lowest similarity are often the sites which initial EBQI notation is close to a threshold between
534 two statuses (e.g., 7.53 is a very good notation but very close to the good status < 7.50).

535 **4 Discussion**

536 **4.1 An original Ecosystem-Based Quality Index for the Coastal detrital bottoms**

537 This paper proposes an original Ecosystem-Based Quality Index to assess the health status of the
538 Coastal Detrital Bottoms in the North-western Mediterranean context. The goal is to provide (i) a useful
539 tool, embracing the ecosystem-based approach concept, for coastal managers (MPAs, local
540 authorities), and (ii) arguments for a better consideration of this key habitat according to the MSFD
541 and Barcelona Convention. To define a relevant biological indicator, the main issue is finding the
542 balance between the most suitable descriptors versus the feasible methods according to available
543 human and material resources. Unlike ecosystem of priority interest such as *Posidonia oceanica*
544 meadows (Montefalcone, 2009; Lopez y Royo et al., 2010; Personnic et al., 2014; Oprandi et al., 2021),
545 very few indices or descriptors are available for CDB functional or ecosystem-based analysis.

546 EBQI is a suitable tool to assess broadly the functioning of an ecosystem (Boudouresque et al., 2020a,
547 2020b). It aims at providing a first integrated insight with a general notation and status per
548 compartments, useful at the scale of a sampling site or in the frame of a monitoring network at larger
549 scale. The CI for CDB, between 88 to 93%, is by far higher than the mean CI assessed for sites where
550 other EBQIs indices were defined: 53% for *Posidonia oceanica* seagrass meadows (Personnic et al.,
551 2014), 62% for undersea caves (Rastorgueff et al., 2015), and 74% for rocky reefs (Thibaut et al.,
552 2017).

553 Our analysis put in evidence the influence of both natural features and anthropogenic activities on the
554 ecological status of CDB. Sites in areas without trawling or dredging activities, far from urbanization
555 show the best notation. The Provence and French Riviera coast provides a large gradient of
556 anthropogenic pressure and local natural specificities. This heterogeneity was the key for defining an
557 EBQI for CDB and testing the reliability of the descriptors of the functional compartments. A further
558 analysis will benefit of new and detailed data to identify the causes of such a status: natural feature
559 (hydrological context, geology, adjacent habitats) or pressures linked with human activities (trawling,
560 terrigenous input, coastal development, etc.). As for all point measurement methods to assess the
561 ecological quality, EBQI needs a high number of replicates per site to give a better insight into the
562 structure of the ecosystem assessed. This approach aims at offering a broader view of the ecosystem
563 functioning.

564 According to our results, the protocol proposed is accurate, using feasible methods by scuba diving,
565 photographs, photoquadrats and videos. The robustness analysis showed an effect of a perturbation of
566 the ecological status per box or weighting. Nevertheless, the percentage of similarity remained high
567 for a relatively moderate perturbation. The probability of 25% was tested to simulate a theoretical
568 application with one in four chances of being wrong, which is consistent and closer to the reality of
569 field application. Keeping in mind that the EBQI aims at a broad assessment of ecosystem quality and
570 functioning, the results confirmed the robustness of the approach.

571 **4.2 Critics and improvement perspectives**

572 It would have been relevant to assess properly the macrofauna of the sediment instead of organic matter
573 measurement (Box 7), which would have improved the quality of the assessment, at ecosystem scale,
but increasing the time-consumption of the sampling. The index AMBI (AZTI's Marine Biotic Index: Borja et al., 2000, 2003), applied for the Water Framework Directive, allows the assessment of the ecological status of soft bottoms based on the macrofauna of the sediment. It considers the abundance in the sediment of species sensitive to stressors, tolerant and opportunist. It can give good and reliable information about infauna status to complete and improve the ecosystem-based assessment. The macrofauna of the sediment is of importance in terms of ecological functioning and trophic interactions with epibenthic and demersal communities (Austen et al., 2002), and obviously, an assessment considering only the organic matter content is far from being enough (Cocito et al., 1990). It could also be argued that while the proper identification of CDB must be based on the infauna (Pérès and Picard, 1964), the index here presented focuses mostly on the epibenthos. However, characterization and evaluation are two distinct steps of environmental diagnostics (Bianchi et al., 2012): evaluation criteria can be applied only after the habitat in question has been characterized. We do believe that the health status of the CDB epibenthic facies is an acceptable proxy for the quality of the whole ecosystem; that is why we have decided to assign the highest weighting to the Box 1 (Rhodoliths), which could be discussed. All the direct anthropogenic physical pressures mentioned in the previous pages obviously threaten epibenthos first, rather than infauna; and as far as we know, also the ongoing seawater warming is affecting epibenthic species more than the infauna (Cerrano et al., 2000; Garrabou et al., 2009). But it may be true that the degradation of the CDB epibenthic facies may not necessarily imply a bad status for the infauna, and further research is needed.

Rhodolith beds from CDB can be considered both soft and hard substrata, according to its benthic communities (Jacquotte, 1962; Hall-Spencer, 1998; Basso et al., 2017). Rhodolith beds are also described as a step towards the edification of coralligenous banks, from a soft bottom towards a hard bottom, in specific environmental conditions (Basso et al., 2007). The pioneer zoologist André Fortuné Marion named ‘coralligenous gravels’ the rhodolith beds of the Gulf of Marseille (Marion, 1883). The ‘*Coralligène de plateau*’ described by Laborel (1961), Pérès and Picard (1951, 1964) and Bellan-Santini et al. (1994) is a coralligenous bank developed from the growing and coalescence of rhodoliths. It highlights the key-role of calcareous macroalgae in inducing autogenic ecological succession (Laborel, 1961; Laubier, 1966; Odum, 1971; Begon et al., 1976; Basso et al., 2007). In some circumstances, the epibenthic associations of the CDB, particularly rhodolith beds, can be considered at the threshold between a circalittoral sandy bottom and an actual upcoming coralligenous bank. A CDB facies with small concretionary boulders has also been described (Meinesz et al., 1983). This does not mean that CDB should be equated to a hard substrate. The slow evolution towards a coralligenous bank can not be generalized to all CDB, even in presence of rhodolith beds.

Bryozoan facies, as described by Bianchi (2009a) and Harmelin (2017), have not been found in the 29 sampling sites considered in the present work. The patchiness of epibenthic associations and facies and the rarity of such a feature might explain our result. Yet, *Pentapora fascialis* facies are known for example around Port-Cros Island (Holon and Harmelin, 2014; Harmelin, 2017) but were not found during our investigations. Such rarity increases the conservation issue and the importance of protecting and monitoring CDB. Bryozoans are known to contribute significantly to the bioclastic part of soft bottoms worldwide (Halfar et al., 2006).

The assessment of widespread and patchy habitat such as CDB requires a seascape approach. It is known that the seascape can influence directly the trophic network and the ecosystem functioning (Boström et al., 2011; Abadie et al., 2018; Santos et al., 2022). In that consideration, a seascape approach should be a potential suitable descriptor to assess the quality of an ecosystem (e.g., marine forests, habitat structure, etc.; Cheminée et al., 2014; Thiriet et al., 2014). We have proposed a combination of methods to provide a large and as representative as possible assessment, involving
620 direct observation via scuba diving, photoquadrats and seascape videos, considering functional
621 ecosystem compartments structuring the seascape. The compartments assessed described structuring
622 communities (filter and suspension feeders, rhodoliths) which contribute to the seascape. For example,
623 Gobert et al. (2014) proposed the LIMA index, which is based on a topographical and a biological
624 description and could be applied on all type of habitat from 0 to 40 m depth. Such approach could be
625 of interest for CDB hosting structuring facies and associations; in the case of CDB without such
626 features, a low structured seascape cannot be interpreted as a low-functioning ecosystem, considering
627 the macrofauna of the sediment, compartment of importance but with little consequence on the
628 seascape structure (bioturbation, calcified organisms providing bioclastic elements, etc.).

629 Our analysis showed strong and expected correlations between some of the descriptors. Defining an
630 indicator implies the selection of suitable descriptors but not too numerous for an operational
631 implementation. Our purpose was to assess the main compartments of the ecosystem, as defined in Fig.
632 1, using as few descriptors as possible. The correlation observed between the final set of descriptors
633 could lead us to reduce the number of descriptors and then simplify the assessment and avoid
634 redundancy; at the same time, a combination of correlated descriptors assessing different ecological
635 functions improves the robustness. As evoked by Personnic et al. (2014), the removal of correlated
636 boxes might result in a loss of accuracy of the method.

637 An ecosystem-based approach can be useful for Ecosystem Services assessment, providing quantitative
638 data for the different ecosystem compartments (Seitz et al., 2014; Burgos et al., 2017). Such approach
639 has already been carried out for several ecosystems, including seagrass meadows and considering
640 different bundles of ecosystem services according to different quality status (Kermagoret et al., 2019;
641 Scémama et al., 2020).

642 **4.3 A tool to support anthropogenic pressures assessment**

643 The next step should be the design of an anthropogenic pressure assessment tool to estimate the links
644 between ecological status and anthropogenic cumulated pressures (Holon et al., 2015; Guarnieri et al.,
645 2016; Quemmerais-Amice et al., 2020). Assessing anthropogenic pressures is challenging; the
646 moreover, the assessment of human activities can be considered as a good proxy. In the present work,
647 we did not identify visible evidences of trawling or dredging, the main physical pressures affecting
648 CDB. These evidences can be difficult to find, even in long-time trawled areas (Ordines et al., 2017).
649 The main evidences of stress observed were the occurrence of macrowastes (e.g., glass, plastic, fishing
650 gears) and invasive alien species (e.g., *Caulerpa cylindracea*). A complementary approach is needed
651 to better characterize human pressures. Our study sites are not located in areas with an important
652 trawling activity, compared to e.g., the Gulf of Lion, the Catalan Coast or Balearic Islands (Farriols et
653 al., 2017; Jac and Vaz, 2020). New data in different configurations regarding anthropogenic pressures
654 are to be sampled.

655 **4.4 The need for an effective protection**

656 The increase in the surface area of Marine Protected Areas driven by the European Union since the
657 2010s has led the MPAs to extend over the continental shelf, including coastal detrital bottoms. The
658 new borders of these MPAs do not mean automatically an effective protection and management, and
659 it needs time for coastal managers to include these new areas in dashboards and management plans. As
660 a results, the ecological status of CDB sites shows no correlation with the management level to the
661 contrary of Thibaut et al. (2017), who evidenced differences in sublittoral rocky reefs according to the
662 management, and no statistical difference between Natura 2000 and unprotected sites. These results
663
664

highlight the need to enhance the conservation of continental shelf widespread ecosystems such as the CDB, involving the implementation of effective marine protected areas (Sala et al., 2021).

665
666
667
668
669

The conservation or the restoration of CDB implies the decreasing or at least the regulation of anthropogenic pressures to allow a natural resilience of communities identified as impacted by such activities. In that case, the role of effective MPAs is limited to the regulation or prohibition of some human activities: e.g., trawling, dredging, artisanal fishing, mooring. The regulation of other pressures (e.g., terrigenous inputs, NIS spreading, eutrophication, sedimentation) asks for larger scale policies.

670

## 4.5 EBQI implementation for CDB

671
672
673
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675
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677
678
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684

As an indicator embracing the concept of the ecosystem-based approach, the EBQI defined for CDB aims to provide relevant and useful data for both European Directives (MSFD, WFD, HD) and local management purposes. Compared to other indicators dedicated to soft bottoms (e.g., Borja et al., 2000, 2003), the EBQI does not need a strong expertise in taxonomy even if it implies more parameters for its calculation. Fifteen descriptors are needed to assess the EBQI for CDB, 13 for *Posidonia oceanica* seagrass meadows (Personnic et al., 2014) and 10 for infralittoral rocky reefs (Thibaut et al., 2017). Data sampling can be carried out in less than one day per site, involving three operators, which is reasonable to envisage the settlement of a long-term monitoring network at regional (e.g., French Mediterranean coast) or local scale (e.g., MPA; Astruch et al., 2022b). The frame proposed by the EBQI can provide a standardized method to assess the conservation status according to the Habitats Directive (e.g., assessment of the structure and the function of a given habitat), where diagnosis were usually based on expert judgement and broad data. Repeated applications over time would be welcome to evaluate the adequacy of this index to describe change following management actions (Mancini et al., 2020; Oprandi et al., 2022).

685
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689

EBQI on CDB should be applied and tested in contexts with other biogeographic specificities and pressures: oligotrophic, warmer and impacted by non-indigenous species where very few knowledge is available (e.g., South and Eastern Mediterranean Sea). The same approach could also be applied on subtidal rhodolith beds in other areas worldwide of important concern about related human activities (e.g., Brittany).

690

## 5 Conclusion

691
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An original Ecosystem-Based Quality Index (EBQI) for the Coastal Detrital Bottoms (CDB) has been defined, inspired by already existing EBQIs for *Posidonia oceanica* seagrass meadows, coralligenous reefs, underwater marine caves, and infralittoral rocky reefs, all mainly based on the assessment of their epibenthic assemblages. Relatively easy to implement and robust, CDB EBQI provides a relevant tool to assess the quality of this widespread ecosystem in accordance with public policies at national and European levels. In the context of the increase in surface areas of marine protected areas, management goals must include CDB in upcoming plans to secure the conservation of a habitat of importance at the Mediterranean scale. Our approach is mainly focused on epibenthic assemblages and improvement should be needed to better consider the assessment of the macrofauna of the sediment. We suggest applying and testing this approach in other areas within the Mediterranean Sea and outside.

701

## 6 Conflict of Interest

702
703

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
704 **7 Author Contributions**

705 All authors (excepting AO, NM, BM and BD) have participated in a workshop in Marseille in April

706 2019. PA, BB, TS and AO realised the field investigations and the data sampling in 2020 and 2021.

707 All authors contributed to the content for their associated sections. TS and AO produced the statistical

708 analysis. PA compiled content from all authors and prepared the final version. All authors have

709 reviewed and agreed to the submission of the final version.

710 **8 Funding**

711 The present work was granted by the French Biodiversity Office in the frame of the ACDSea project.

712 **9 Acknowledgments**

713 This work was carried out in the frame of the ACDSea project (Assessment of Coastal Detrital

714 ecosystem conservation Status: an ecosystem-based approach). We kindly thank the French

715 Biodiversity Office for financial support, the experts involved in the working out of the index, Michèle

716 Perret-Boudouresque for documentation assistance, and Michael Paul for proof-reading of the text.

717 This work is dedicated to the memory of our late colleague Boris Daniel, involved in the ACDSea

718 project since the first steps.

719 **10 References**

720 Abadie, A., Pace, M., Gobert, S., Borg, J. A. (2018). Seascape ecology in *Posidonia oceanica* seagrass meadows: Linking structure and ecological processes for management. *Ecological Indicators*, 87, 1-13.

722 Agnesi, S., Annunziatellis, A., Inghilesi, R., Mo, G., Orasi, A. (2020). The contribution of wind-wave energy at sea bottom to the modelling of rhodolith beds distribution in an offshore continental shelf. *Mediterranean Marine Science*, 21 (2): 433-441.

725 Aguado-Giménez, F. and Ruiz-Fernández, J. M. (2012). Influence of an experimental fish farm on the spatio-temporal dynamic of a Mediterranean maerl algae community. *Marine Environmental Research*, 74, 47-55.

727 Aguilar, R., Pastor, X., Torriente, A., Garcia, S. (2009). Deep-sea coralligenous beds observed with ROV on four seamounts in the western Mediterranean. In: Pergent-Martini C., Brichet M. (eds), UNEP-MAP-RAC/SPA Proceedings of the 1st Mediterranean symposium on the conservation of the coralligenous and other calcareous bio-concretions. *Tabarka, Tunisia*, 15-16 January 2009, 148-150.

731 Amado-Filho, G. M., Pereira-Filho, G. H. (2012). Rhodolith beds in Brazil: a new potential habitat for marine bioprospection. *Revista Brasileira de Farmacognosia*, 22, 782-788.

733 Amado-Filho, G. M., Bahia, R. G., Pereira-Filho, G. H., Longo, L. L. (2017). South Atlantic rhodolith beds: latitudinal distribution, species composition, structure and ecosystem functions, threats and conservation status. In *Rhodolith/Maërl Beds: A Global Perspective*, Springer, Cham., 299-317.

736 Anderson, M. J., 2001. A new method for non-parametric multivariate analysis of variance. *Austral Ecology* 26, 32-46.

737 Aouissi, M., Sellam, L. N., Boudouresque, C. F., Blanfuné, A., Derbal, F., Frihi, H., et al. (2018). Insights into the species diversity of the genus *Sargassum* (Phaeophyceae) in the Mediterranean Sea, with a focus on a previously unnoticed taxon from Algeria. *Mediterranean Marine Science*, 19(1), 48-57.

740 Astruch, P., Boudouresque, C. F., Bonhomme, D., Goujard, A., Antonioli, P. A., Bonhomme, P., et al. (2012). Mapping and state of conservation of benthic marine habitats and assemblages of Port-Cros national Park (Provence, France, northwestern Mediterranean Sea). *Scientific Reports of Port-Cros National Park*, 26: 45-90.

743 Astruch, P., Goujard, A., Rouanet, E., Boudouresque, C. F., Verlaque, M., Berthier, L., et al. (2019). Assessment of the conservation status of Coastal Detrital sandy bottoms in the Mediterranean Sea: an Ecosystem-based Approach in the framework of the ACDSea project. *Proceedings of the 3rd Mediterranean Symposium on the conservation of coralligenous and other calcareous bio-concretions* (Antalya, Turquie, 15-16 january 2019), 23-29.
747 Astruch, P., Orts, A., Schohn, T., Belloni, B., Ballesteros, E., Bianchi, et al. (2022a). Towards an ecosystem-based index to assess the ecological status of Mediterranean coastal detrital bottoms. In: Bouafif, C., Ouerghi, A. (Eds), Proceedings of the 4th Mediterranean Symposium on the conservation of Coralligenous & other Calcareous Bio-Concretions. SPA/RAC, Tunis, 137-138.

751 Astruch, P., Schohn, T., Belloni, B., Cassetti, O., Cabral, M., Ruitton, S., et al. (2022b). Involving managers in the ecosystem-based assessment of marine habitats: a case study in French Catalonia. In: Bouafif, C., Ouerghi, A. (Eds), Proceedings of the 7th Mediterranean Symposium on Marine vegetation Mediterranean Symposia on Marine Vegetation. SPA/RAC, Tunis,

755 Augier, H. and Boudouresque, C. F. (1975). Dix ans de recherches dans la zone marine du parc national de Port-Cros-Troisième partie. *Annales de la SSNAT*, 27 : 133-170.

757 Augier, H. and Boudouresque, C. F. (1978). Végétation marine de l'île de Port-Cros (Parc national) XVI : Contribution à l'étude de l'épiflore du détritique côtier. Travaux Scientifiques du Parc national de Port-Cros, 4 : 101-125.

759 Austen, M. C., Lambshead, P. J. D., Hutchings, P. A., Boucher, G., Snelgrove, P. V. R., Heip, C., et al. (2002). Biodiversity links above and below the marine sediment-water interface that may influence community stability. Biodiversity & Conservation, 11 (1), 113-136.

762 Azam, F., Fenchel, T., Field, J. G., Gray, J. S., Meyer-Reil, L. A., Thingstad, F. (1983). The ecological role of water-column microbes in the sea. Marine Ecology Progress Series 10:257-263.

764 Ballesteros, E. (1994). The Deep-Water *Peyssonnelia* Beds from the Balearic Islands (Western Mediterranean). Marine Ecology, 15(3-4), 233-253.

766 Ballesteros, E. (2006). Mediterranean Coralligenous assemblages: a synthesis of present knowledge. *Oceanography and Marine Biology: An Annual Review*, 2006, 44, 123-195.

768 Ballesteros, E., Torras, X., Pinedo, S., García, M., Mangialajo, L., De Torres, M. (2007). A new methodology based on littoral community cartography dominated by macroalgae for the implementation of the European Water Framework Directive. Marine pollution bulletin, 55(1-6), 172-180.

771 Bănaru, D., Harmelin-Vivien, M., Gomoiu, M. T., Onciu, T. M. (2007). Influence of the Danube River inputs on C and N stable isotope ratios of the Romanian coastal waters and sediment (Black Sea). Marine Pollution Bulletin, 54 : 1385-1384.

773 Bănaru, D., Mellon-Duval, C., Roos, D., Bigot, J.L., Souplet, A., Jadaud, A., Beaubrun, P., Fromentin, J.M. (2013) Trophic interactions in the Gulf of Lions ecosystem (northwestern Mediterranean) and fishing impacts. ICES Journal of Marine Systems, 111-112, 45-68.

776 Barbera, C., Bordehore, C., Borg, J. A., Glémarec, M., Grall, J., Hall-Spencer, J. M., et al. (2003). Conservation and management of northeast Atlantic and Mediterranean maerl beds. Aquatic conservation: marine and freshwater ecosystems, 13(S1), S65-S76.

779 Basso, D. (2012). Carbonate production by calcareous red algae and global change. Geodiversitas, 34(1), 13-33.

780 Basso, D., Nalin, R., Massari, F. (2007). Genesis and composition of the Pleistocene Coralligène de plateau of the Cutro Terrace (Calabria, southern Italy). Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 244(2), 73-182.

782 Basso, D., Quaranta, F., Vannucci, G., Piazza, M. (2012). Quantification of the coralline carbonate from a Serravallian rhodolith bed of the Tertiary Piedmont Basin (Stazzano, Alessandria, NW Italy). Geodiversitas, 34(1), 137-149.

784 Basso, D., Babbini, L., Kaleb, S., Bracchi, V., Falace, A. (2016). Monitoring deep Mediterranean rhodolith beds. Aquatic Conservation: Marine and Freshwater Ecosystem, 26: 549-561.

786 Basso, D., Babbini, L., Ramos-Esplá, A. A., Salomidi, M. (2017). Mediterranean rhodolith beds. In Rhodolith/Maerl Beds: a global perspective, Springer, Cham., 281-298.

788 Bellan, G., Bellan-Santini, D., Picard, J. (1980). Mise en évidence de modèles éco-biologique dans des zones soumises à perturbations par matières organiques. Oceanologica Acta, 3(3), 383-390.

790 Bellan-Santini, D., Lacaze, J. C., Poizat, C. (1994). Les biocénoses marines et littorales de Méditerranée. Synthèse, menaces et perspectives. Collection Patrimoines naturels, volume 19. Secrétariat de la faune et de la flore / MNHN, Paris, 246 p.

792 Begon, M., Harper, J. L., Townsend, C. R. (1986): Ecology. Individuals, populations and communities. – 854 pp.; Oxford (Blackwell Scientific Publications).
794

795

796

Bensettiti, F., Bioret, F., Roland, J., Lacoste, J. P. (2004). Cahiers d'habitats Natura 2000. Connaissance et gestion des habitats et des espèces d'intérêt communautaire. Tome 2 - Habitats côtiers. MEDD/MAAPAR/MNHN. Ed. La Documentation française, Paris, 399 pp.

797

Bergbauer, M., Humberg, B. (2000). La vie sous-marine en méditerranée, Guide Vigot, ed. Vigot, 318p.

798

799

800

Bermejo, R., Chefaoui, R. M., Engelen, A. H., Buonomo, R., Neiva, J., Ferreira-Costa, J., et al. (2018). Marine forests of the Mediterranean-Atlantic *Cystoseira tamariscifolia* complex show a southern Iberian genetic hotspot and no reproductive isolation in parapatry. Scientific Reports, 8, 10427.

801

802

803

Bernard, G., Romero-Ramirez, A., Tauran, A., Pantalos, M., Deflandre, B., Grall, J., et al. (2019). Declining maerl vitality and habitat complexity across a dredging gradient: Insights from *in situ* sediment profile imagery (SPI). Scientific reports, 9(1), 1-12.

804

805

806

807

Bianchi, C. N. (2009a). Gli habitat prioritari del protocollo SPA/BIO (Convenzione di Barcellona) presenti in Italia. Schede descrittive per l'identificazione. IV. 2. 2. 10. Facies a grandi briozoi - Priority habitats according to the SPA/BIO protocol (Barcelona Convention) present in Italy. Identification sheets. IV. 2. 2. 10. Facies with large bryozoans. Biologia Marina Mediterranea, 16 (Suppl. 1), 209-212.

808

809

810

811

Bianchi, C. N. (2009b). Gli habitat prioritari del protocollo SPA/BIO (Convenzione di Barcellona) presenti in Italia. Schede descrittive per l'identificazione. III. 6. 1.14. Facies a *Cladocora caespitosa* - Priority habitats according to the SPA/BIO protocol (Barcelona Convention) present in Italy. Identification sheets. III. 6. 1.14. Facies with *Cladocora caespitosa*.

812

813

Bianchi, C. N., Ardizzone, D., Belluscio, A., Colantoni, P., Diviacco, G., Morri, C., Tunesi, L. (2004). Benthic cartography. Biologia Marina Mediterranea, 11 (suppl. 1), 347-370.

814

815

816

Bianchi, C. N., Azzola, A., Bertolino, M., Betti, F., Bo, M., Cattaneo-Vietti, R., Cocito, S., Montefalcone, M., Morri, C., Oprandi, A., Peirano, A., Bavestrello, G. (2019a). Consequences of the marine climate and ecosystem shift of the 1980-90s on the Ligurian Sea biodiversity (NW Mediterranean). The European Zoological Journal, 86 (1), 458-487.

817

818

Bianchi, C. N., Azzola, A., Parravicini, V., Peirano, A., Morri, C., Montefalcone, M. (2019b). Abrupt change in a subtidal rocky reef community coincided with a rapid acceleration of sea water warming. Diversity, 11, 215.

819

820

821

Bianchi, C.N., Azzola, A., Cocito, S., Morri, C., Oprandi, A., Peirano, A., Sgorbini, S., Montefalcone, M. (2022). Biodiversity monitoring in Mediterranean marine protected areas: scientific and methodological challenges. Diversity, 14, 43.

822

823

Bianchi, C. N., Parravicini, V., Montefalcone, M., Rovere, A., Morri, C. (2012). The challenge of managing marine biodiversity: a practical toolkit for a cartographic, territorial approach. Diversity, 4, 419-452.

824

825

Blanchard, J. L., Jennings, S., Law, R., Castle, M. D., McCloghrie, P., Rochet, M. J., et al. (2009). How does abundance scale with body size in coupled size-structured food webs? Journal of Animal Ecology, 78(1), 270-280.

826

827

828

Blanfuné, A., Thibaut, T., Boudouresque, C. F., Mačić, V., Markovic, L., Palomba, L., et al. (2017). The CARLIT method for the assessment of the ecological quality of European Mediterranean waters: Relevance, robustness and possible improvements. Ecological indicators, 72, 249-259.

829

Bond, W. (2001). Keystone species–hunting the snark? Science 292, 63–64.

830

831

Bordehore, C., Borg, J. A., Lanfranco, E., Espla, A. A., Rizzo, M., Schembri, P. J., (2000). Trawling as a major threat to Mediterranean maerl beds. First Mediterranean Symposium on Marine Vegetation, Ajaccio. 105-109.

832

833

834

Bordehore, C., Ramos-Esplá, A. A., Riosmena-Rodríguez, R. (2003). Comparative study of two maerl beds with different otter trawling history, southeast Iberian Peninsula. Aquatic Conservation: Marine and Freshwater Ecosystems, 13(S1), S43-S54.

835

836

Borja, A., Franco, J., Pérez, V. (2000). A marine biotic index to establish the ecological quality of soft-bottom benthos within European estuarine and coastal environments. Marine Pollution Bulletin, 40, 1100–1114.

837

838

Borja, A., Muxika, I., Franco, J. (2003). The application of a Marine Biotic Index to different impact sources affecting soft-bottom benthic communities along European coasts. Marine Pollution Bulletin, 46, 835–845.

839

840

841

Borja, A., Menchaca, I., Garmendia, J. M., Franco, J., Larreta, J., Sagarminaga, Y., et al. (2021). Big insights from a small country: The added value of integrated assessment in the marine environmental status evaluation of Malta. Frontiers in Marine Science, 375.
842 Bosellini, A., Ginsburg, R. N. (1971). Form and internal structure of recent algal nodules (rhodolites) from Bermuda. The Journal of Geology, 79(6), 669-682.

844 Boström, C., Pittman, S. J., Simenstad, C., Kneib, R. T. (2011). Seascape ecology of coastal biogenic habitats: advances, gaps, and challenges. Marine Ecology Progress Series, 427: 191–217

846 Boudouresque, C. F. (2015). Taxonomy and phylogeny of unicellular eukaryotes. In Environmental Microbiology: Fundamentals and Applications. Springer, 191-257.

848 Boudouresque, C. F., Denizot, M. (1973). Recherches sur le genre *Peyssonnelia* (Rhodophycées) *I. Peyssonnelia rosa-marina* sp. nov. et *Peyssonnelia bornetii* sp. nov. *Giornale Botanico Italiano*, 107: 17-27.

850 Boudouresque, C. F., Verlaque, M. (2002). Biological pollution in the Mediterranean Sea: invasive versus introduced macrophytes. Marine Pollution Bulletin, 44(1), 32-38.

852 Boudouresque, C. F., Pergent, G., Pergent-Martini, C., Ruitton, S., Thibaut, T., Verlaque, M. (2016). The necromass of the *Posidonia oceanica* seagrass meadow: fate, role, ecosystem services and vulnerability. Hydrobiologia, 781(1), 25-42.

854 Boudouresque, C. F., Astruch, P., Goujard, A., Rouanet, E., Bonhomme, D., Bonhomme, P. (2019). The withdrawal of the lower limit of the *Posidonia oceanica* seagrass meadow in the Bay of Hyères (NW Mediterranean): a combination of natural and human-induced recent and ancient phenomena? In: Proceedings of the 6th Mediterranean symposium on marine vegetation, Antalya, Turkey, 14-15 January 2019, LANGAR H., OUERGHI A. édits., RAC/SPA publ., Tunis: 35-40.

858 Boudouresque, C. F., Astruch, P., Bănaru, D., Blanfuné, A., Carlotti, F., Faget, D., et al. (2020a). Global change and the management of Mediterranean coastal habitats: a plea for a socio-ecosystem-based approach. In: Evolution of Marine Coastal Ecosystems under the Pressure of Global Changes, Springer, 297-320.

861 Boudouresque, C. F., Astruch, P., Bănaru, D., Blanfuné, A., Belloni, B., Changeux, T. et al. (2020b). Ecosystem-based quality indices: valuable tools for environment management. Vie Milieu - Life Environment, 70 (3-4): 2-15.

863 Bourcier, M. (1982). Nouvelles localisations et délimitation fine de quelques faciès de la biocénose des fonds détritiques côtiers du PN Port-Cros. *Travaux Scientifiques du Parc national de Port-Cros*, 8: 19-24.

865 Bourcier, M. (1985). Localisation et délimitation de quelques faciès de la biocénose des fonds Détritiques Côtiers dans la partie nord du PN de Port-Cros. *Parc national de Port-Cros Ed.*, Scientific Reports of Port-Cros national Park, 11: 181-183.

867 Bourcier, M. (1988). Macrobenthos de substrat meuble circalittoral autour de l'île de Port-Cros. *Parc national de Port-Cros Ed.*, Scientific Reports of Port-Cros National Park, 14: 41-64.

869 Bourcier, M., Zibrowius, H. (1973). Red Muds Dumped in the La Cassidaigne (Marseille Region), Observations with the Sp 350 Dipping Saucer (June 1971), and Results of Dredgings. *Bulletin Signalétique C.N.R.S.*, 740-1973, 34, (11-12), 15190.

872 Bruno de Sousa, C., Cox, C. J., Brito, L., Pavão, M. M., Pereira, H., Ferreira, A., et al. (2019). Improved Phylogeny of Brown Algae *Cystoseira* (Fucales) from the Atlantic-Mediterranean Region Based on Mitochondrial Sequences. *PLoS ONE*, 14, e0210143.

875 Burgos, E., Montefalcone, M., Ferrari, M., Paoli, C., Vassallo, P., Morri, C., Bianchi, C. N. (2017). Ecosystem functions and economic wealth: Trajectories of change in seagrass meadows. *Journal of cleaner production*, 168, 1108-1119.

877 Burrows, M. T., Kamenos, N. A., Hughes, D. J., Stahl, H., Howe, J. A., Tett, P. (2014). Assessment of carbon budgets and potential blue carbon stores in Scotland's coastal and marine environment. *Scottish Natural Heritage Commissioned Report No. 761*.

880 Cerrano, C., Bavestrello, G., Bianchi, C. N., Calcinai, B., Cattaneo-Vietti, R., Morri, C. et al. (2001). The role of sponge bioerosion in Mediterranean coralligenous accretion. In Mediterranean Ecosystems (pp. 235-240). Springer, Milano.

882 Cerrano, C., Bavestrello, G., Bianchi, C. N., Cattaneo-Vietti, R., Bava, S., Morganti, C., Morri, C., Picco, P., Sara, G., Schiaparelli, S., Siccardi, A., Sponga, F. (2000). A catastrophic mass-mortality episode of gorgonians and other organisms in the Ligurian Sea (North-western Mediterranean), summer 1999. *Ecology Letters*, 3, 284-293.

885 Cheminée, A., Feunteun, E., Clerici, S., Cousin, B., Francour, P. (2014). Management of infralittoral habitats: towards a seascape scale approach. In *Underwater Seascapes* (pp. 161-183). Springer, Cham.

887 Chen, C. T., Carlotti, F., Harmelin-Vivien, M., Lebreton, B., Guillou, G., Vassallo, L., et al. (2022). Diet and trophic interactions of Mediterranean planktivorous fishes. *Marine Biology*, 169(9), 1-18.
889 Cocito, S., Fanucci, S., Niccolai, I., Morri, C., Bianchi, C. N. (1990). Relationships between trophic organization of benthic
890 communities and organic matter content in Tyrrhenian Sea sediments. Hydrobiologia, 207(1), 53-60.

891 Connell, S. D., Foster, M. S., Airoldi, L. (2014). What are algal turfs? Towards a better description of turfs. Marine Ecology
892 Progress Series, 495, 299-307.

893 Costa, S. (1960). Recherches sur les fonds à *Halarachnion spatulatum* de la baie de Marseille. Vie et Milieu 11, 1-68.

894 Cresson, P., Ruitton, S., Harmelin-Vivien, M. (2014). Artificial reefs do increase secondary biomass production: mechanisms evidenced by stable isotopes. Marine Ecology Progress Series, 509, 15-26.

896 Cresson, P., Chouvelon, T., Bustamante, P., Bănaru, D., Baudrier, J., Le Loc’h, F. et al. (2020). Primary production and depth drive different trophic structure and functioning in French marine ecosystems. Progress in Oceanography, 186 (102343): 1-14.

899 Darnaude, A. M. (2005). Fish ecology and terrestrial carbon use in coastal areas: implications for marine fish production.
900 J. Animal Ecology, 74: 864-876.

901 De Bettignies T., La Rivière M., Delavenne J., Dupré S., Gaudillat V., Janson A.-L., et al. (2021). Interprétation française des Habitats d'Intérêt Communautaire marins. PatriNat (OFB-CNRS-MNHN), Paris, 58 p.

903 De Grave, S., Whitaker, A. (1999). Benthic community re-adjustment following dredging of a muddy-maerl matrix. Marine Pollution Bulletin, 38(2), 102-108.

905 Deidun, A., Marrone, A., Gauci, A., Galdies, J., Lorenti, M., Mangano, M. C., Cutajar, K., Mirto, S., Sarà, G. (2022).
906 Structure and biodiversity of a Maltese maerl bed: New insight into the associated assemblage 24 years after the first
907 investigation. Regional Studies in Marine Science, 52, 102262.

908 Dell'Anno, A., Mei, M. L., Pusceddu, A., Danovaro, R. (2002). Assessing the trophic state and eutrophication of coastal marine systems: a new approach based on the biochemical composition of sediment organic matter. Marine Pollution Bulletin, 44(7), 611-622.

911 Demestre, M., Muntadas, A., Sanchez, P., Garcia-de-Vinuesa, A., Mas, J., Franco, I. et al. (2017). Bio and Anthropogenic Disturbance of Maërl Communities Settled on Subaqueous Dunes on the Mar Menor Continental Shelf (Western Mediterranean). In Atlas of Bedforms in the Western Mediterranean. Springer, 215-219.

914 De Ridder, C., Lawrence, J. M. (1982). Food and feeding mechanisms: Echinoidea. In Echinoderm nutrition: 57-1 15.
915 Jangoux M. and Lawrence J M. (Eds). Rotterdam: Balkema.

916 Dutertre, M., Grall, J., Ehrhold, A., Hamon, D. (2015). Environmental factors affecting maerl bed structure in Brittany (France). European Journal of Phycology, 50(4), 371-383.

918 Enrichetti, F., Bo, M., Morri, C., Montefalcone, M., Toma, M., Bavestrello, G., Tunesi, L., Canese, S., Giusti, M., Salvati, E., Bertolotto, R. M., Bianchi, C. N. (2019). Assessing the environmental status of temperate mesophotic reefs: a new, integrated methodological approach. Ecological Indicators, 102, 218-229.

921 Farriols, M. T., Ordines, F., Somerfield, P. J., Pasqual, C., Hidalgo, M., Guijarro, B. et al. (2017). Bottom trawl impacts on Mediterranean demersal fish diversity: not so obvious or are we too late? Continental Shelf Research, 137, 84-102.
923 http://dx.doi.org/10.1016/j.csr.2016.11.011

924 Fornos, J. J., Ballesteros, E., Massutti, C., Rodriguez-Perea, A. (1988). Red algae sediments in the Balearic shelf. Rapports et Procès Verbaux des Réunions Commission Internationale pour l'Exploration Scientifique de la mer Méditerranée, 31(2): 86-86.

927 Foster, M. S. R., Riosmena-Rodriguez, R., Steller, D. L., Woelkerling, W. J. (1997). Living rhodolith beds in the Gulf of California and their implications. Pliocene carbonates and related facies flanking the Gulf of California, Baja California, Mexico. Geological Society of America special paper, (318), 127-139.

930 Foster, M. S., Amado Filho, G. M., Kamenos, N. A., Riosmena-Rodríguez, R., Steller, D. L. (2013). Rhodoliths and rhodolith beds. Research and discoveries: The revolution of science through scuba.

932 Fragkopoulou, E., Serrão, E. A., Horta, P. A., Koerich, G., Assis, J. (2021). Bottom Trawling Threatens Future Climate Refugia of Rhodoliths Globally. Frontiers in Marine Science, 7, 1246.

934 Francour, P. (1989). L'oursin *Centrostephanus longispinus* en Méditerranée occidentale : résultats d'une enquête sur sa répartition et son écologie. Vie Marine, H.S. n°10, Actes du VI séminaire international sur les Echinodermes 1988): 138-147.
937 Francour, P. (1991). Statut de *Centrostephanus longispinus* en Méditerranée. Colloque internation. Espèces marines à protéger en Méditerranée, Boudouresque C.F., Avon M., Gravez V. eds., GIS Posidonie publ., Marseille: 187-202.

939 Garrabou, J., Coma, R., Bensoussan, N., Bally, M., Chevaldonné, P., Cigliano, M., Diaz, D., Harmelin, J. G., Gambi, M. C., Kersting, D. K., Ledoux, J. B., Lejeusne, C., Linares, C., Marschal, C., Pérez, T., Ribes, M., Romano, J. C., Serrano, E., Teixido, N., Torrents, O., Zabala, M., Zuberer, F., C., Cerrano, C. (2009). Mass mortality in Northwestern Mediterranean rocky benthic communities: effects of the 2003 heat wave. *Global Change Biology*, 15 (5), 1090-1103.

943 Gatti, G., Bianchi, C. N., Morri, C., Montefalcone, M., Sartoretto, S. (2015). Coralligenous reefs state along anthropized coasts: application and validation of the COARSE index, based on a rapid visual assessment (RVA) approach. *Ecological Indicators*, 52, 567-576.

946 Gautier, Y., Picard, J. (1957). Bionomie du banc de Magaud (Est des Iles d'Hyères). Recueil des Travaux de la Station Marine d'Endoume, 28-42.

948 Gayet, G., Baptist, F., Maciejewski, L., Poncet, R., Bensettiti, F. (2018). Guide de détermination des habitats terrestres et marins de la typologie EUNIS - version 1.0. AFB, collection Guides et protocoles, 230 p.

950 Giakoumi, S., Halpern, B. S., Michel, L. N., Gobert, S., Sini, M., Boudouresque, C. F., et al. (2015). Towards a framework for assessment and management of cumulative human impacts on marine food webs. *Conservation Biology*, 29(4), 1228-1234.

953 Giuliani, S., Lamberti, C. V., Sonni, C., Pellegrini, D. (2005). Mucilage impact on gorgonians in the Tyrrhenian Sea. *Science of the Total Environment*, 353(1-3), 340-349.

955 Gobert, S., Chéry, A., Volpon, A., Pelaprat, C., Lejeune, P. (2014). The seascape as an indicator of environmental interest and quality of the Mediterranean benthos: the *in situ* development of a description index: the LIMA. In *Underwater Seascapes*. Springer, 277-291.

958 Gobert, S., Sartoretto, S., Rico-Raimondino, V., Andral, B., Chery, A., Lejeune, P. et al. (2009). Assessment of the ecological status of Mediterranean French coastal waters as required by the Water Framework Directive using the Posidonia oceanica Rapid Easy Index: PREI. *Marine Pollution Bulletin*, 58(11), 1727-1733.

961 Guarnieri, G., Bevilacqua, S., De Leo, F., Farella, G., Maffia, A., Terlizzi, A. et al. (2016). The challenge of planning conservation strategies in threatened seascapes: understanding the role of fine scale assessments of community response to cumulative human pressures. *PloS ONE*, 11(2), e0149253.

964 Halfar, J., Strasser, M., Riegl, B., Godinez-Orta, L. (2006). Oceanography, sedimentology and acoustic mapping of a bryomol carbonate factory in the northern Gulf of California, Mexico. In: PEDLEY, H. M. & CARANNANTE, G. (eds) 2006. *Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls*. Geological Society, London, Special Publications, 255, 197-215.

968 Hall-Spencer, J. M. (1998). Conservation issues relating to maerl beds as habitats for molluscs. *Journal of Conchology* special publication 2, 271-286.

970 Hall-Spencer, J. M., Harvey, B. P. (2019). Ocean acidification impacts on coastal ecosystem services due to habitat degradation. *Emerging Topics in Life Sciences*, 3(2), 197-206.

972 Harmelin, J. G. (1978). Bryozoaires des Iles d'Hyères; II : inventaire des fonds détritiques. Parc national de Port-Cros Ed., Travaux Scientifiques du Parc national de Port-Cros, 4: 127-148.

974 Harmelin, J. G. (2017). *Pentapora fascialis*, a bryozoan under stress: condition on coastal hard bottoms at Port-Cros Island (Port-Cros national Park, France, Mediterranean) and other sites. *Scientific Reports of Port-Cros National Park*, 31: 125-133.

977 Harmelin, J. G., Duval, C. (1983). Localisation et dissémination des jeunes de l'oursin *Sphaerechinus granularis* (Lamarck) en Méditerranée. Rapports et Procès-verbaux des Réunions Commission Internationale pour l'Exploration Scientifique de la Mer Méditerranée, Monaco, 28, 267-269.

980 Harmelin, J. G., Harmelin-Vivien, M. L. (1976). Observations *in situ* des aires de ponte de *Spicara smaris* (Pisces, Perciformes, Centracanthidae) dans les eaux de Port-Cros. *Travaux Scientifiques du Parc national de Port-Cros*, 2, 115-120.

983 Harmelin-Vivien, M. L., Harmelin, J. G., Chauvet, C., Duval, C., Galzin, R., Lejeune, P. et al. (1985). Evaluation visuelle des peuplements et populations de poisons, méthodes et problèmes. *Revue d'écologie*, 40, 467-539.
985

986

Harvey, A. S., Harvey, R. M., Merton, E. (2017). The distribution, significance and vulnerability of Australian rhodolith beds: a review. Marine and Freshwater Research, 68(3), 411-428.

987

988

Holon, F., Harmelin, J. G. (2014). Bryozoan reef, an unknown Mediterranean habitat? International Bryozoology Association Bulletin, 10, 3.

989

990

991

Holon, F., Mouquet, N., Boissery, P., Bouchoucha, M., Delaruelle, G., Tribot, A. S. et al. (2015). Fine-scale cartography of human impacts along French Mediterranean coasts: a relevant map for the management of marine ecosystems. PLoS ONE, 10(8), e0135473.

992

993

Huvé, H. (1954). Contribution à l'étude des fonds à *Peyssonnelia polymorpha* (Zan.) Schmitz de la région de Marseille. Recueil des Travaux de la Station marine d'Endoume, 12 : 119-136.

994

995

996

Jac, C., Vaz, S. (2020) Abrasion superficielle des fonds par les arts trainants – Méditerranée (surface Swept Area Ratio). Surface abrasion of seabeds by bottom contacting fishing gears - Mediterranean Sea (surface Swept Area Ratio). IFREMER http://dx.doi.org/10.12770/8bed2328-a0fa-4386-8a3e-d6d146cafe54

997

998

Jacquotte, R. (1962). Etude des fonds de maërl de Méditerranée. Recueil des Travaux de la Station marine d'Endoume, Fr., 28 (41): 141-235.

999

1000

James, D. W., Foster, M. S., O'Sullivan, J. (2006). Bryoliths (Bryozoa) in the Gulf of California.1. Pacific Science, 60(1), 117-124.

1001

1002

1003

Jódar-Pérez, A. B., Terradas-Fernández, M., López-Moya, F., Asensio-Berbegal, L., López-Llorca, L. V. (2020). Multidisciplinary Analysis of *Cystoseira* sensu lato (SE Spain) Suggest a Complex Colonization of the Mediterranean. Journal of Marine Science and Engineering, 8(12), 961.

1004

1005

1006

Joher, S., Ballesteros, E., Cebrian, E., Sánchez, N., Rodríguez-Prieto, C. (2012). Deep-water macroalgal-dominated coastal detritic assemblages on the continental shelf off Mallorca and Menorca (Balearic Islands, Western Mediterranean). Botanica marina, 55 (5): 485-497.

1007

1008

1009

Joher, S., Ballesteros, E., Rodríguez-Prieto, C. (2015). Contribution to the study of deep coastal detritic bottoms: the algal communities of the continental shelf off the Balearic Islands, Western Mediterranean. Mediterranean Marine Science, 16(3): 573-590.

1010

Jones, N. S. (1950). Marine bottom communities. Biological Reviews, 25 (3), 283-313.

1011

1012

Kamenos, N. A., Moore, P. G., Hall-Spencer, J. M. (2004). Nursery-area function of maërl grounds for juvenile queen scallops *Aequipecten opercularis* and other invertebrates. Marine Ecology Progress Series, 274, 183-189.

1013

1014

Katsanevakis, S., Wallentinus, I., Zenetos, A., Leppäkoski, E., Çinar, M. E., Oztürk, B. et al. (2014). Impacts of invasive alien marine species on ecosystem services and biodiversity: a pan-European review. Aquatic Invasions, 9(4), 391-423.

1015

1016

1017

Kermagoret, C., Claudet, J., Derolez, V., Nugues, M. M., Ouisse, V., Quillien, N., et al. (2019). How does eutrophication impact bundles of ecosystem services in multiple coastal habitats using state-and-transition models. Ocean & Coastal Management, 174, 144-153.

1018

1019

Kersting, D. K., Cebrian, E., Verdura, J., Ballesteros, E. (2017a). Rolling corals in the Mediterranean Sea. Coral Reefs, 36 (1), 245-245.

1020

1021

Kersting, D. K., Cebrian, E., Verdura, J., Ballesteros, E. (2017b). A new *Cladocora caespitosa* population with unique ecological traits. Mediterranean Marine Science, 18 (1), 38-42.

1022

1023

Khoury, C. (1987). Ichtyofaune des herbiers de posidonies du Parc National de Port-Cros : composition, éthologie alimentaire et rôle dans le réseau trophique (Doctoral dissertation, Aix-Marseille 2).

1024

1025

Klein, J., Verlaque, M. (2008). The *Caulerpa racemosa* invasion: a critical review. Marine pollution bulletin, 56(2), 205-225.

1026

1027

Klein, J. C., Verlaque, M. (2009). Macroalgal assemblages of disturbed coastal detritic bottoms subject to invasive species. Estuarine, coastal and shelf science, 82(3), 461-468.

1028

1029

Konar, B., Riosmena-Rodriguez, R., Iken, K. (2006). Rhodolith bed: a newly discovered habitat in the North Pacific Ocean. Botanica Marina 49 (2006): 355-359

1030

1031

Laborel, J. (1961). Le concrétionnement algal "coralligène" et son importance geomorphologique en Méditerranée. – Recueil des traveaux de la Station marine, Endoume, 23: 37-60
1032 Laborel, J., Pérès, J., Picard, M., Vacelet, J. (1961). Etude directe des fonds des parages de Marseille de 30 à 300 m avec la soucoupe plongeante Cousteau. Bulletin de l'Institut Océanographique de Monaco, 58 : 1-5.

1034 Laborel, J., Tailliez, P., Vacelet, J. (1976). Premières observations dans les eaux du parc national de Port-Cros à l'aide du sous-marin "Griffon" de la Marine Nationale. Travaux Scientifiques du Parc national de Port-Cros, 2: 121-130.

1036 Laffoley, D., Maltby, E., Vincent, M. A., Mee, L., Dunn, E., Gilliland, P. et al. (2004). The Ecosystem Approach. Coherent actions for marine and coastal environments. A report to the UK government. Peterborough, English Nature, 65 p.

1038 La Rivière, M., Aish, A., Auby, I., Ar Gall, E., Dauvin, J.C., de Bettignies, T. et al. (2017). Evaluation de la sensibilité des habitats élémentaires (DHFF) d'Atlantique, de Manche et de Mer du Nord aux pressions physiques. Rapport SPN 2017-4. MNHN. Paris, 93 p.

1041 La Rivière, M., Michez, N., Delavenne, J., Andres, S., Fréjefond, C., Janson, A. L. et al. (2021). Fiches descriptives des biocénoses benthiques de Méditerranée. UMS PatriNat (OFB-CNRS-MNHN), Paris, 660 p.

1043 Laubier, L. (1966). Le coralligène des Albères. Monographie biocénotique. – Annales Institut Océanographique, Paris, 43/2: 137-316.

1045 Littler, M. M., Littler, D. S. (1980). The evolution of thallus form and survival strategies in benthic marine macroalgae: field and laboratory tests of a functional form model. The American Naturalist, 116 (1), 25-44.

1047 Lombardi, C., Taylor, P. D., Cocito, S. (2014). Bryozoan constructions in a changing Mediterranean Sea. In: Goffredo, S., Dubinsky, Z. (eds.), The Mediterranean Sea: Its history and present challenges. Springer, Dordrecht, 373-384.

1049 Lopez y Royo, C. L., Casazza, G., Pergent-Martini, C., Pergent, G. (2010). A biotic index using the seagrass *Posidonia oceanica* (BiPo), to evaluate ecological status of coastal waters. Ecological Indicators, 10(2), 380-389.

1051 Maciejewski, L., Lepareur, F., Viry, D., Bensettiti, F., Puissauve, R., Touroult, J. (2016). État de conservation des habitats: propositions de définitions et de concepts pour l'évaluation à l'échelle d'un site Natura 2000. Revue d'Ecologie, Terre et Vie, 71(1), 3-20.

1054 Mancini, I., Rigo, I., Oprandi, A., Montefalcone, M., Morri, C., Peirano, A., Vassallo, P., Paoli, C., Bianchi, C. N. (2020). What biotic indices tell us about ecosystem change: lessons from the seagrass *Posidonia oceanica*. Indices application on historical data. Vie et Milieu - Life and Environment, 70 (3-4), 55-61.

1057 Mao, J., Burdett, H. L., McGill, R. A., Newton, J., Gulliver, P., Kamenos, N. A. (2020). Carbon burial over the last four millennia is regulated by both climatic and land use change. Global Change Biology, 26(4), 2496-2504.

1059 Marion, A. F. (1883). Esquisse d'une topographie zoologique du golfe de Marseille (Vol. 1, No. 1). Cayer et cie.

1060 Martin, S., Hall-Spencer, J. M. (2017). Effects of ocean warming and acidification on rhodolith/maërl beds. In Rhodolith/maërl beds: A global perspective, Springer, 55-85.

1062 Martin, S., Clavier, J., Chauvaud, L., Thouzeau, G. (2007). Community metabolism in temperate maërl beds. I. Carbon and carbonate fluxes. Marine Ecology Progress Series, 335, 19-29.

1064 Martin, C. S., Giannoulaki, M., De Leo, F., Scardi, M., Salomidi, M., Knittweis, L. et al. (2014). Coralligenous and maërl habitats: predictive modelling to identify their spatial distributions across the Mediterranean Sea. Scientific Reports, 4(1), 1-9.

1067 Meinesz, A., Belsher, T., Thibaut, T., Antolic, B., Mustapha, K. B., Boudouresque, C. F. et al. (2001). The introduced green alga *Caulerpa taxifolia* continues to spread in the Mediterranean. Biological invasions, 3(2), 201-210.

1069 Meinesz, A., Boudouresque, C. F., Falconetti, C., Astier, J. M., Bay, D., Blanc, J. J., Bourcier, M., Cinelli, F., Cirik, S., Cristiani, G., Di Geronimo, I., Giaccone, G., Harmelin, J. G., Laubier, L., Lovric, A. Z., Molinier, R., Soyer, J., Vamvakas, C. (1983). Normalisation des symboles pour la représentation et la cartographie des biocénoses benthiques littorales de Méditerranée. Annales de l'Institut Océanographique, 59 (2), 155-172.

1073 Michez, N., Dirberg, G., Bellan-Santini, D., Verlaque, M., Bellan, G., Pergent, G. et al. (2011). Typologie des biocénoses benthiques de Méditerranée, Liste de référence française et correspondances. Rapport SPN-2011 - 13, MNHN, Paris, 50 p.

1075 Michez, N., Fourt, M., Aish, A., Bellan, G., Bellan-Santini, D., Chevaldonné, P. et al. (2014). Typologie des biocénoses benthiques de Méditerranée Version 2. Rapport SPN-2014 - 33, MNHN, Paris, 26 p.

1077 Monnier, B. (2020). Quantification et dynamique spatio-temporelle des puits de carbone associés aux herbiers à *Posidonia oceanica*. (Manuscrit de thèse, Université de Corse Pascal Paoli FRES 3041 – UMR CNRS SPE 6134 Faculté des sciences et techniques), 239 p.
1080 Monnier, B., Pergent, G., Mateo, M. Á., Carbonell, R., Clabaut, P., Pergent-Martini, C. (2021). Sizing the carbon sink associated with *Posidonia oceanica* seagrass meadows using very high-resolution seismic reflection imaging. Marine Environmental Research, 170, 105415.

1083 Monnier, B., Pergent, G., Mateo, M. Á., Clabaut, P., Pergent-Martini, C. (2022). Quantification of blue carbon stocks associated with *Posidonia oceanica* seagrass meadows in Corsica (NW Mediterranean). Science of The Total Environment, 155864.

1086 Montefalcone, M. (2009). Ecosystem health assessment using the Mediterranean seagrass *Posidonia oceanica*: a review. *Ecological Indicators*, 9(4), 595-604.

1088 Montefalcone, M., Albertelli, G., Morri, C., Bianchi, C. N. (2007). Urban seagrass: status of *Posidonia oceanica* off Genoa city waterfront (Italy). Marine Pollution Bulletin, 54, 206-213.

1090 Montefalcone, M., Morri, C., Parravicini, V., Bianchi, C. N. (2015b). A tale of two invaders: divergent spreading kinetics of the alien green algae *Caulerpa taxifolia* and *Caulerpa cylindracea*. Biological Invasions, 17(9), 2717-2728.

1092 Montefalcone, M., Vassallo, P., Gatti, G., Parravicini, V., Paoli, C., Morri, C., Bianchi, C. N. (2015a). The exergy of a phase shift: ecosystem functioning loss in seagrass meadows of the Mediterranean Sea. Estuarine, Coastal and Shelf Science, 156, 186-194.

1095 Morri, C., Bavestrello, G., Bianchi, C. N. (1991). Faunal and ecological notes on some benthic cnidarian species from the Tuscan Archipelago and eastern Ligurian Sea (western Mediterranean). Bollettino dei Musei e degli Istituti Biologici dell'Università di Genova, 54-55 (1988-1989), 27-47.

1098 Morri, C., Peirano, A., Bianchi, C. N., Rodolfo-Metalpa, R. (2000). *Cladocora caespitosa*: a colonial zooxanthellate Mediterranean coral showing constructional ability. Reef Encounter, 27, 22-25.

1100 Mostajir, B., Amblard, C., Buffan-Dubau, E., de Wit, R., Lensi, R., Sime-Ngando, T. (2012). Les réseaux trophiques microbiens des milieux aquatiques et terrestres. J.C. Bertrand et al. Presses Universitaires de Pau et des Pays de l'Adour, 28 p.

1103 Noisette, F., Egilsdottir, H., Davoult, D., Martin, S. (2013). Physiological responses of three temperate coralline algae from contrasting habitats to near-future ocean acidification. Journal of Experimental Marine Biology and Ecology, 448, 179-187.

1106 Odum, E. P. (1971): Fundamentals of ecology. – 574 pp.; Philadelphia (W. B. Saunders Co)

1107 Oprandi, A., Bianchi, C. N., Karayali, O., Morri, C., Rigo, I., Montefalcone, M. (2021). RESQUE: A novel comprehensive approach to compare the performance of different indices in evaluating seagrass health. *Ecological Indicators*, 131, 108118.

1109 Oprandi, A., Mancini, I., Bianchi, C. N., Morri, C., Azzola, A., Montefalcone, M. (2022). Indices from the past: relevance in the status assessment of *Posidonia oceanica* meadows. In: Bouafif, C., Ouerghi, A. (eds), Proceedings of the 7th Mediterranean Symposium on Marine Vegetation. SPA/RAC, Tunis, 72-77.

1112 Ordines, F., Ramón, M., Rivera, J., Rodríguez-Prieto, C., Farriols, M. T., Guijarro, B. et al. (2017). Why long term trawled red algae beds off Balearic Islands (western Mediterranean) still persist? *Regional Studies in Marine Science*, 15, 39-49.

1114 Orekhova, N. A., Ovsyany, E. I. (2020). Organic Carbon and Particle-Size Distribution in the Littoral Bottom Sediments of the Laspi Bay (the Black Sea). *Physical Oceanography*, 27(3), 266-277.

1116 Paoli, C., Morten, A., Bianchi, C. N., Morri, C., Fabiano, M., Vassallo, P. (2016). Capturing ecological complexity: OCI, a novel combination of ecological indices as applied to benthic marine habitats. *Ecological Indicators*, 66, 86-102.

1118 Pérès, J. M. (1967). The Mediterranean benthos. *Oceanography and Marine Biology - Annual Review*, 5, 449-533.

1119 Pérès, J. M. (1982). Zonations and organismic assemblages. In: Kinne, O. (ed.) Marine ecology, Vol. V, Ocean management, Part 1. Wiley, Chichester, 9-642.

1121 Pérès, J. M., Picard, J. (1951): Note sur les fonds coralligènes de la région de Marseille. – Archives de zoologie expérimentale et générale, 88: 24-38.

1123 Pérès, J. M., Picard, J. (1964). Nouveau manuel de bionomie benthique de la mer Méditerranée. Recueil des Travaux de la Station marine d'Endoume, 31 (47): 5-137.

1125 Pergent, G., Agnesi, S., Antonioli, P. A., Babbini, L., Belbacha, S., Ben Mustapha, K., Bianchi, C. N., Bitar, G., Cocito, S., Deter, J., Garrabou, J., Harmelin, J. G., Holon, F., Mo, G., Montefalcone, M., Morri, C., Parravicini, V., Peirano, A.,
1127 Ramos-Esplá, A., Relini, G., Sartoretto, S., Semroud, R., Tunesi, L., Verlaque, M. (2015). Standard methods for inventorying and monitoring coralligenous and rhodoliths assemblages. RAC/SPA, Tunis, 20 pp.

1129 Pergent-Martini, C., Pergent, G., Monnier, B., Boudouresque, C. F., Morri, C., Valette-Sansevin, A. (2021). Contribution of *Posidonia oceanica* meadows in the context of climate change mitigation in the Mediterranean Sea. Marine Environmental Research, 165, 105236.

1132 Personnic, S., Boudouresque, C. F., Astruch, P., Ballesteros, E., Blouet, S., Bellan-Santini, D. et al. (2014). An Ecosystem-Based Approach to Assess the Status of a Mediterranean Ecosystem, the *Posidonia oceanica* Seagrass Meadow. PLoS ONE 9(6): e98994.

1135 Piazzi, L., Cinelli, F. (2000). Effet' de l'expansion des Rhodophyceae introduites *Acrothamnion preissii* et *Womersleyella setacea* sur les communautés algales des rhizomes de *Posidonia oceanica* de Méditerranée occidentale. Cryptogamie Algologie, 21(3), 291-300.

1138 Piazzi, L., Balata, D., Cinelli, F. (2007). Invasions of alien macroalgae in Mediterranean coralligenous assemblages. Cryptogamie-Algologie, 28(3), 289-302.

1140 Piazzi, L., Gennaro, P., Cecchi, E., Bianchi, C. N., Cinti, M. F., Gatti, G., Guala, I., Morri, C., Sartoretto, F., Serena, F., Montefalcone, M. (2021). Ecological status of coralligenous assemblages: ten years of application of the ESCA index from local to wide scale validation. Ecological Indicators, 121, 107077.

1143 Piazzi, L., Gennaro, P., Montefalcone, M., Bianchi, C. N., Cecchi, E., Morri, C., Serena, F. (2019). STAR: An integrated and standardized procedure to evaluate the ecological status of coralligenous reefs. Aquatic Conservation: Marine and Freshwater Ecosystems, 29, 189-201.

1146 Picard, J. (1965). Recherches qualitatives sur les biocénoses marines des substrats meubles dragables de la région marseillaise. Recueil des Travaux de la Station Marine d'Endoume, 52(36), 1-160 (10).

1148 Pikaver, A. H., Gilbert, C., Breton, F. (2004). An indicator set to measure the progress in the implementation of integrated coastal zone management in Europe. Ocean & Coastal Management, 47: 449-462.

1150 Provan, J. I. M., Murphy, S., Maggs, C. A. (2005). Tracking the invasive history of the green alga *Codium fragile* ssp. tomentosoides. Molecular Ecology, 14(1), 189-194.

1152 Quemmerais-Amice, F., Barrere, J., La Rivière, M., Contin, G., Bailly, D. (2020). A methodology and tool for mapping the risk of cumulative effects on benthic habitats. Frontiers in Marine Science, 7, 569205.

1154 R core team (2022). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/.

1156 Rastorgueff, P. A., Bellan-Santini, D., Bianchi C. N., Bussotti, S., Chevaldonné, P., Guidetti, P. et al. (2015). An ecosystem-based approach to evaluate the ecological quality of Mediterranean undersea caves. Ecological Indicators, 54: 137-152.

1158 Rees, I. (1999). Lag Veneer: a missing piece in the benthic biotopes jigsaw? Newsletter PMNHS, 2, 24-26.

1159 Rendina, F., Ferrigno, F., Appolloni, L., Donnarumma, L., Sandulli, R., Fulvio, G. (2020). Anthropic pressure due to lost fishing gears and marine litter on different rhodolith beds off the Campania Coast (Tyrrhenian Sea, Italy). Ecological Questions, 31(4), 1-17.

1162 Reynes, L., Thibaut, T., Mauger, S., Blanfuné, A., Holon, F., Cruaud, C., Couloux A. et al. (2021). Genomic signatures of clonality in the deep water kelp *Laminaria rodriguezii*. Molecular Ecology, 30(8), 1806-1822.

1164 Rowe, G., Wright, G. (1999). The Delphi technique as a forecasting tool: issues and analysis. International Journal of Forecasting, Volume 15, Issue 4, October 1999.

1166 Ruitton, S., Astruch, P., Blanfuné, A., Cabral, M., Thibaut, T., Boudouresque, C.F. (2020). Bridging risk assessment of human pressure and ecosystem status. Vie et Milieu/Life & Environment, 70(3-4), 37-53.

1168 Ruitton, S., Boudouresque, C. F., Thibaut T., Rastorgueff, P. A., Personnic, S., Boissery, P. et al. (2017). Guide méthodologique pour l'évaluation écosystémique des habitats marins. Frances. MIO publ., 161 p. DOI: 10.13140/RG.2.2.23411.02085

1171 Ruitton, S., Personnic, S., Ballesteros, E., Bellan-Santini, D., Boudouresque, C. F., Chevaldonné, P., et al. (2014). An ecosystem-based approach to assess the status of the Mediterranean coralligenous habitat. *Proceedings of the 2nd Mediterranean symposium on the conservation of coralligenous and other calcareous bio-concretions*. Bouafif, C., Langar, H., Ouerghi, A. (eds.), RAC/SPA publ., Tunis: 153-158.
1175 Sala, E., Mayorga, J., Bradley, D., Cabral, R. B., Atwood, T. B., Auber, A., et al. (2021). Protecting the global ocean for biodiversity, food and climate. *Nature*, 1-6. https://doi.org/10.1038/s41586-021-03371-z

1177 Salomidi, M., Katsanevakis, S., Borja, A., Braeckman, U., Damalas, D., et al., 2012. Assessment of goods and services, vulnerability, and conservation status of European seabed biotopes: a stepping stone towards ecosystem-based marine spatial management. *Mediterranean Marine Science*, 13 (1), 49-88.

1180 Santos, R. O., James, W. R., Nelson, J. A., Rehage, J. S., Serafy, J., Pittman, S. J., Lirman, D. (2022). Influence of seascape spatial pattern on the trophic niche of an omnivorous fish. *Ecosphere*, 13(2), e3944.

1182 Sanz-Lázaro, C., Belando, M. D., Marín-Guirao, L., Navarrete-Mier, F., Marín, A. (2011). Relationship between sedimentation rates and benthic impact on maerl beds derived from fish farming in the Mediterranean. *Marine Environmental Research*, 71(1), 22-30.

1185 Sartoretto, S., Schohn, T., Bianchi, C. N., Morri, C., Garrabou, J., Ballesteros, E., Ruitton, S., Verlaque, M., Daniel, B., Charbonnel, E., Blouet, S., David, R., Féral, J. P., Gatti, G. (2017). An integrated method to evaluate and monitor the conservation state of coralligenous habitats: the INDEX-COR approach. *Marine Pollution Bulletin*, 120, 222-231.

1188 Savini, A., Basso, D., Bracchi, V. A., Corselli, C., Pennetta, M. (2012). Maerl-bed mapping and carbonate quantification on submerged terraces offshore the Cilento peninsula (Tyrrhenian Sea, Italy), *Geodiversitas*, 34(1), 77-98.

1190 Scémama, P., Kermagoret, C., Accornero-Picon, A., Alban, F., Astruch, P., Boemare, C., et al. (2020). A strategic approach to assess the bundle of ecosystem services provided by *Posidonia oceanica* meadows in the Bay of Marseille. *Vie et Milieu/Life & Environment*, 70(3-4), 197-207.

1193 Schiaparelli, S., Castellano, M., Povero, P., Sartoni, G., Cattaneo-Vietti, R. (2007). A benthic mucilage event in North-Western Mediterranean Sea and its possible relationships with the summer 2003 European heatwave: short term effects on littoral rocky assemblages. *Marine Ecology*, 28(3), 341-353.

1196 Sciberras, M., Rizzo, M., Mifsud, J.R., Camilleri, K., Borg, J. A., Lanfranco, E. et al. (2009). Habitat structure and biological characteristics of maerl bed off the northeastern coast of the Maltese Islands (central Mediterranean). *Marine. Biodiversity*, 39, 251-264.

1199 Seitz, R. D., Wennhage, H., Bergström, U., Lipcius, R. N., Ysebaert, T. (2014). Ecological value of coastal habitats for commercially and ecologically important species. *ICES Journal of Marine Science*, 71(3), 648-665.

1201 Somaschini, A., Martini, N., Gravina, M. F., Belluscio, A., Corsi, F., Ardizzone, G. D. (1998). Characterization and cartography of some Mediterranean soft-bottom benthic communities (Ligurian Sea, Italy). *Scientia Marina*, 62 (1-2), 27-36.

1204 Soykan, O., İlkyaz, A. T., Metin, G., Kinacigil, H. T. (2010). Growth and reproduction of blotched picarel (*Spicara maena* Linnaeus, 1758) in the central Aegean Sea, Turkey. *Turkish Journal of Zoology*, 34(4), 453-459.

1206 Souto, J., Reverter-Gil, O., Fernandez-Pulpeiro, E. 2010. Bryozoa from detritic bottoms in the Menorca Channel (Balearic Islands, western Mediterranean), with notes on the genus *Cribellopora*. *Zootaxa*, 2536(1), 36-52.

1208 Stamouli, C., Zenetos, A., Kallianiotis, A., Voultsiadou, E. 2022. Megabenthic invertebrate diversity in Mediterranean trawlable soft bottoms: a synthesis of current knowledge. *Mediterranean Marine Science*, 23 (3): 447-459.

1210 Steller, D. L., Riosmena-Rodríguez, R., Foster, M. S., Roberts, C. A. (2003). Rhodolith bed diversity in the Gulf of California: the importance of rhodolith structure and consequences of disturbance. *Aquatic conservation: marine and freshwater ecosystems*, 13(S1), S5-S20.

1213 Thibaut, T., Blanfuné, A., Boudouresque, C. F., Personnic, S., Ruitton, S., Ballesteros, E., et al. (2017). An ecosystem-based approach to assess the status of Mediterranean algae-dominates shallow rocky reefs. *Marine Pollution Bulletin* 117: 311-329.

1216 Thibaut, T., Blanfuné, A., Verlaque, M., Boudouresque, C. F., Ruitton, S. 2016. The *Sargassum* conundrum: very rare, threatened or locally extinct in the NW Mediterranean and still lacking protection. *Hydrobiologia*, 781(1), 3-23.

1218 Thiriet, P., Cheminée, A., Mangialajo, L., Francour, P. (2014). How 3D complexity of macrophyte-formed habitats affect the processes structuring fish assemblages within coastal temperate seascapes?. In *Underwater Seascapes* (pp. 185-199). Springer, Cham.

1221 Valette-Sansevin, A., Pergent, G., Buron, K., Pergent-Martini C., Damier, E. (2019). Continuous mapping of benthic habitats along the coast of Corsica: A tool for the inventory and monitoring of blue carbon ecosystems. *Mediterranean Marine Science*, 20(3), 585-593.
1224 Van der Heijden, L. H., Kamenos, N. A. (2015). Reviews and syntheses: calculating the global contribution of coralline
1225 algae to total carbon burial. Biogeosciences, 12(21), 6429-6441.

1226 Vassallo, P., Bianchi, C. N., Paoli, C., Holon, F., Navone, A., Bavestrello, G., Cattaneo Vietti, R., Morri C. (2018). A
1227 predictive approach to benthic marine habitat mapping: Efficacy and management implications. Marine Pollution Bulletin,
1228 131, 218-232.

1229 Velimirov, B., Herndl, G., Kavka, G. (1984). Biomass distribution and physiological capabilities of bacteria in the water
1230 column above a sea grass system. In 2. Colloque International de Bacteriologie Marine, Brest (France), 1-5.

1231 Verlaque, M. (1990). Relations entre *Sarpa salpa* (Linnaeus, 1758) (Téléostéen, Sparidae), les autres poissons brouteurs et
1232 le phytobenthos algal méditerranéen. Oceanologica acta, 13(3), 373-388.

1233 Vidondo, B., Duarte, C. M. (1995). Seasonal growth of Codium bursa, a slow-growing Mediterranean macroalga: in situ
1234 experimental evidence of nutrient limitation. Marine Ecology Progress Series, 123, 185-191.

1235 Watanabe, K., Yoshida, G., Hori, M., Umezawa, Y., Moki, H., Kuwae, T. (2020). Macroalgal metabolism and lateral carbon
1236 flows can create significant carbon sinks. Biogeosciences, 17(9), 2425-2440.

1237 Weinberg, S. (1996). Decouvrir la Méditerranée. Nathan Nature, Avon, France, 352 pp.

1238 Wilkie, I. C., Carnevali, M. C., Andrietti, F. (1996). Mechanical properties of the peristomial membrane of the cidaroid
1239 sea-urchin *Stylocidaris affinis*. Journal of Zoology, 238(3), 557-569.

1240 Wirtz, P., Debelius, H. (2003). Mediterranean and Atlantic invertebrate guide from Spain to Turkey, from Norway to
1241 Equator, ConchBooks, Hackenheim, Allemagne, 305p.

1242
<table><caption>Table 1. Sampling sites position (DD: decimal degrees), depth at upper and deep zones (m) and management level (MPA: Marine Protected area; NTZ: No-take zone; MUM: Multi-use management).</caption><thead><tr><th rowspan="2">Code</th><th rowspan="2">Sites</th><th colspan="3">Upper zone</th><th colspan="3">Deep zone</th><th rowspan="2">Management level</th></tr><tr><th>Latitude DD</th><th>Longitude DD</th><th>Z (m)</th><th>Latitude DD</th><th>Longitude DD</th><th>Z (m)</th></tr></thead><tbody><tr><td>01COU</td><td>La Couronne</td><td>43.318006</td><td>5.068738</td><td>36</td><td>43.309006</td><td>5.069218</td><td>54</td><td>Natura 2000</td></tr><tr><td>02CAR</td><td>Carry</td><td>43.322321</td><td>5.181404</td><td>37</td><td>43.31703</td><td>5.185064</td><td>51</td><td>Natura 2000</td></tr><tr><td>03PRA</td><td>Baie du Prado</td><td>43.249276</td><td>5.341165</td><td>32</td><td>43.238208</td><td>5.311782</td><td>51</td><td>MPA-MUM</td></tr><tr><td>04PLA</td><td>Planier</td><td>43.189937</td><td>5.224995</td><td>33</td><td>43.187317</td><td>5.226625</td><td>58</td><td>MPA-NTZ</td></tr><tr><td>05PR</td><td>Passe de Riou</td><td>43.183998</td><td>5.367319</td><td>42</td><td>43.185715</td><td>5.355298</td><td>59</td><td>MPA-NTZ</td></tr><tr><td>06SUG</td><td>Sugiton</td><td>43.207808</td><td>5.461533</td><td>40</td><td>43.20354</td><td>5.461815</td><td>62</td><td>MPA-MUM</td></tr><tr><td>07CC</td><td>Cap Canaille</td><td>43.188278</td><td>5.550706</td><td>39</td><td>43.186743</td><td>5.547737</td><td>62</td><td>MPA-NTZ</td></tr><tr><td>08IVE</td><td>Île Verte</td><td>43.158016</td><td>5.614341</td><td>49</td><td>43.154661</td><td>5.608425</td><td>68</td><td>MPA-MUM</td></tr><tr><td>09EMB</td><td>Embiez</td><td>43.077151</td><td>5.740709</td><td>38</td><td>43.076248</td><td>5.733459</td><td>63</td><td>Natura 2000</td></tr><tr><td>10AMP</td><td>Amphitria</td><td>43.043668</td><td>5.84977</td><td>39</td><td>43.041536</td><td>5.850354</td><td>61</td><td>Natura 2000</td></tr><tr><td>11DF</td><td>Deux Frères</td><td>43.052152</td><td>5.869729</td><td>41</td><td>43.051563</td><td>5.875795</td><td>62</td><td>Natura 2000</td></tr><tr><td>12TGR</td><td>Toulon Grande Rade</td><td>43.094181</td><td>6.001158</td><td>37</td><td>43.075055</td><td>5.995539</td><td>64</td><td>No protection</td></tr><tr><td>13FG</td><td>Fourmigue de Giens</td><td>43.042368</td><td>6.067969</td><td>42</td><td>43.035908</td><td>6.068579</td><td>64</td><td>MPA-MUM</td></tr><tr><td>14POR</td><td>Porquerolles Est</td><td>43.013374</td><td>6.257428</td><td>38</td><td>43.03322</td><td>6.297224</td><td>49</td><td>MPA-MUM</td></tr><tr><td>15HB</td><td>Baie d'Hyères</td><td>43.064543</td><td>6.273882</td><td>40</td><td>43.054147</td><td>6.360791</td><td>63</td><td>MPA-MUM</td></tr><tr><td>16BAG</td><td>Passe de Bagaud</td><td>43.015193</td><td>6.376252</td><td>41</td><td>43.022061</td><td>6.383424</td><td>63</td><td>MPA-MUM</td></tr><tr><td>17VAI</td><td>Vaisseau</td><td>42.993327</td><td>6.404658</td><td>41</td><td>42.9905</td><td>6.404757</td><td>65</td><td>MPA-NTZ</td></tr><tr><td>18CAV</td><td>Cavalaire</td><td>43.173947</td><td>6.555193</td><td>39</td><td>43.16926</td><td>6.560022</td><td>58</td><td>Natura 2000</td></tr><tr><td>19CT</td><td>Cap Taillat</td><td>43.166685</td><td>6.659678</td><td>43</td><td>43.152653</td><td>6.669391</td><td>79</td><td>Natura 2000</td></tr><tr><td>20CAM</td><td>Cap Camarat</td><td>43.193892</td><td>6.712775</td><td>41</td><td>43.188749</td><td>6.718136</td><td>68</td><td>Natura 2000</td></tr><tr><td>21PAM</td><td>Pampelonne</td><td>43.255746</td><td>6.758933</td><td>42</td><td>43.255049</td><td>6.766981</td><td>66</td><td>No protection</td></tr><tr><td>22ST</td><td>Saint Tropez</td><td>43.288836</td><td>6.642193</td><td>35</td><td>43.292658</td><td>6.664679</td><td>51</td><td>No protection</td></tr><tr><td>23SAR</td><td>Sardinaux</td><td>43.31683</td><td>6.697555</td><td>44</td><td>43.318675</td><td>6.707096</td><td>60</td><td>No protection</td></tr><tr><td>24DRA</td><td>Dramont</td><td>43.408298</td><td>6.842286</td><td>43</td><td>43.406108</td><td>6.836703</td><td>60</td><td>Natura 2000</td></tr><tr><td>25AGA</td><td>Agay</td><td>43.41966</td><td>6.86717</td><td>41</td><td>43.417686</td><td>6.871251</td><td>61</td><td>Natura 2000</td></tr><tr><td>26EST</td><td>Esterel</td><td>43.4493</td><td>6.92991</td><td>39</td><td>43.449293</td><td>6.934245</td><td>61</td><td>MPA-NTZ</td></tr><tr><td>27TH</td><td>Théoule sur mer</td><td>43.50549</td><td>6.957715</td><td>28</td><td>43.506943</td><td>6.960811</td><td>50</td><td>MPA-MUM</td></tr><tr><td>28ANT</td><td>Cap Antibes</td><td>43.541966</td><td>7.127123</td><td>36</td><td>43.537103</td><td>7.126363</td><td>59</td><td>Natura 2000</td></tr><tr><td>29VIL</td><td>Villefranche sur mer</td><td>43.691278</td><td>7.319585</td><td>41</td><td>43.692724</td><td>7.314388</td><td>58</td><td>Natura 2000</td></tr></tbody></table>

1245

1246
1247 Table 2. Boxes, descriptors, weight (W) and status for the EBQI assessment (POM: Particulate Organic

1248 Matter; HOM: High Organic Matter; LOM: Low Organic Matter).

<table><thead><tr><th rowspan="2">Box</th><th rowspan="2">Descriptors</th><th rowspan="2">W</th><th colspan="5">Status</th></tr><tr><th>4</th><th>3</th><th>2</th><th>1</th><th>0</th></tr></thead><tbody><tr><td rowspan="2">1</td><td rowspan="2">Rhodoliths</td><td>% cover (upper zone)</td><td rowspan="2">6</td><td>≥ 20 %</td><td>20 > x ≥ 10 %</td><td>10 > x ≥ 5 %</td><td>5 > x > 0 %</td><td>0 %</td></tr><tr><td>% cover (deep zone)</td><td>≥ 10 %</td><td>10 > x ≥ 5 %</td><td>5 > x ≥ 1 %</td><td>1 > x > 0 %</td><td>0 %</td></tr><tr><td rowspan="2">2</td><td rowspan="2">Perennial macroalgae</td><td>% cover (upper zone)</td><td rowspan="2">4</td><td>≥ 2 %</td><td>2 > x ≥ 1 %</td><td>1 > x ≥ 0.2 %</td><td>0.2 > x ≥ 0 %</td><td>0 %</td></tr><tr><td>% cover (deep zone)</td><td>≥ 10 %</td><td>10 > x ≥ 5 %</td><td>5 > x ≥ 1 %</td><td>1 > x > 0 %</td><td>0 %</td></tr><tr><td rowspan="2">3-4</td><td rowspan="2">Seasonal erected macroalgae</td><td>% cover (upper zone)</td><td rowspan="2">4</td><td>≥ 5 %</td><td>5 > x ≥ 2 %</td><td>2 > x ≥ 1 %</td><td>1 > x > 0 %</td><td>0 %</td></tr><tr><td>% cover (deep zone)</td><td>≥ 2</td><td></td><td>1</td><td></td><td>0</td></tr><tr><td>5</td><td>Herbivores</td><td>Alpha taxonomic richness</td><td>2</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>6</td><td>Sedimented POM</td><td>% pelitic (&lt; 63 µm) in the sediment</td><td>2</td><td>&lt;0.02 %</td><td>0.05 > x ≥ 0.02 %</td><td>0.1 > x ≥ 0.05 %</td><td>1 > x ≥ 0.1 %</td><td>≥ 1 %</td></tr><tr><td>7</td><td>Infauna</td><td>% Organic Matter in the sediment (status +2 if matter or remains of Posidonia oceanica in the sample)</td><td>5</td><td>3 > x ≥ 2 %</td><td>4 > x ≥ 3 %</td><td>5 > x ≥ 4 %</td><td>2 > x ≥ 0 %</td><td>≥ 5 %</td></tr><tr><td>8</td><td>Organic macrodetritus</td><td>% cover by litter</td><td>2</td><td>10 > x ≥ 5 %</td><td>5 > x ≥ 1 %</td><td>&lt; 1 %</td><td>25 > x ≥ 10 %</td><td>≥ 25 %</td></tr><tr><td>9a</td><td>Detritivores HOM</td><td>Mean density per m²</td><td rowspan="2">3</td><td>0</td><td>0.6 > x > 0</td><td>1 > x ≥ 0.6</td><td>2 > x ≥ 1</td><td>≥ 2</td></tr><tr><td>9b</td><td>Detritivores LOM</td><td>Mean density per m²</td><td>≥ 2</td><td>2 > x ≥ 1</td><td>1 > x ≥ 0.6</td><td>0.6 > x > 0</td><td>0</td></tr><tr><td>10</td><td>Filter- and Suspension-feeders</td><td>Mean density per m²</td><td>4</td><td>≥ 30</td><td>30 > x ≥ 15</td><td>15 > x ≥ 10</td><td>10 > x ≥ 5</td><td>&lt; 5</td></tr><tr><td>11</td><td>Planktivores</td><td>Alpha specific richness</td><td>1</td><td>≥ 2</td><td>-</td><td>1</td><td>-</td><td>0</td></tr><tr><td>12a</td><td>Carnivorous invertebrates</td><td>Alpha taxonomic richness</td><td rowspan="2">3</td><td>≥ 5</td><td>4</td><td>3</td><td>2</td><td>≤ 1</td></tr><tr><td>12b</td><td>Carnivorous vertebrates</td><td>Alpha taxonomic richness</td><td>≥ 5</td><td>4</td><td>3</td><td>2</td><td>≤ 1</td></tr></tbody></table>

1249

1250
<table><caption>Table 3. Method for the assessment of the descriptors for each functional compartment.</caption><thead><tr><th>Box</th><th>Descriptors</th><th>Method</th></tr></thead><tbody><tr><td rowspan="2">1</td><td rowspan="2">Rhodoliths</td><td>% cover (upper zone)</td><td>Photoquadrats (80 cm × 80 cm) at upper zone</td></tr><tr><td>% cover (deep zone)</td><td>Photoquadrats (80 cm × 80 cm) at intermediate zone</td></tr><tr><td>2</td><td>Perennial macroalgae</td><td>% cover (upper zone)</td><td>Photoquadrats (80 cm × 80 cm) at upper zone</td></tr><tr><td rowspan="2">3-4</td><td rowspan="2">Seasonal macroalgae</td><td>% cover (upper zone)</td><td>Photoquadrats (80 cm × 80 cm) at upper zone</td></tr><tr><td>% cover (deep zone)</td><td>Photoquadrats (80 cm × 80 cm) at intermediate zone</td></tr><tr><td>5</td><td>Herbivores</td><td>Alpha taxonomic richness</td><td>SCUBA, photoquadrats and seascape videos</td></tr><tr><td>6</td><td>Sedimented POM</td><td>% pelitic (&lt; 63 µm) in the sediment</td><td>3 sediment cores sampled per site. Grain size analysis (&lt; 63 µm)</td></tr><tr><td>7</td><td>Infauna</td><td>% OM in the sediment (status +2 if matte or <i>Posidonia oceanica</i> remains in the sample)</td><td>3 sediment cores sampled per site. After drying the samples 48h at 60°C, burn it 4h at 400°C. The difference between the dry weight and the remains after burning is the dry mass of OM.</td></tr><tr><td>8</td><td>Organic macrodetritus</td><td>% cover by litter</td><td>Photoquadrats (80 cm × 80 cm) at the 2 depths</td></tr><tr><td>9a</td><td>Detritivores HOM</td><td>Mean density per m²</td><td>Photoquadrats (80 cm × 80 cm) at the 2 depths</td></tr><tr><td>9b</td><td>Detritivores LOM</td><td>Mean density per m²</td><td>Photoquadrats (80 cm × 80 cm) at the 2 depths</td></tr><tr><td>10</td><td>Filter- and Suspension-feeders</td><td>Mean density per m²</td><td>Photoquadrats (80 cm × 80 cm) at the 2 depths</td></tr><tr><td>11</td><td>Planktivores</td><td>Alpha specific richness</td><td>SCUBA, photoquadrats and seascape videos</td></tr><tr><td>12a</td><td>Carnivorous invertebrates</td><td>Alpha taxonomic richness</td><td>SCUBA, photoquadrats and seascape videos</td></tr><tr><td>12b</td><td>Carnivorous vertebrates</td><td>Alpha taxonomic richness</td><td>SCUBA, photoquadrats and seascape videos</td></tr></tbody></table>

1252

<table><caption>Table 4. Ecological status according to EBQI notation.</caption><thead><tr><th>Colour code</th><th>Ecological status</th><th>EBQI notation</th></tr></thead><tbody><tr><td></td><td>Very good</td><td>EBQI ≥ 7.5</td></tr><tr><td></td><td>Good</td><td>7.5 &gt; EBQI ≥ 6</td></tr><tr><td></td><td>Intermediate</td><td>6 &gt; EBQI ≥ 4.5</td></tr><tr><td></td><td>Poor</td><td>4.5 &gt; EBQI ≥ 3.5</td></tr><tr><td></td><td>Bad</td><td>EBQI &lt; 3.5</td></tr></tbody></table>

1254

1255
Table 5. Confidence index (CI) related with data quality or expert judgement (Criteria from Personnic et al., 2014).

<table><thead><tr><td>CI</td><td>Criteria</td></tr></thead><tbody><tr><td>4</td><td>Field data available, recent, and suitable with the recommended methods</td></tr><tr><td>3</td><td>Field data recent, partially completed with expert judgement</td></tr><tr><td>2</td><td>No quantitative field data but recent expert judgement</td></tr><tr><td>1</td><td>No quantitative field data but ancient expert judgement</td></tr><tr><td>0</td><td>No quantitative field data and no suitable expert judgement</td></tr></tbody></table>

1258

1259
1260 Table 6. EBQI notation, status per box and Circularity value (Cir.) for the 29 sampling sites (see Fig.

1261 2 for location). Red: Poor; Yellow: Bad; Green: Intermediate; Blue: Good; Dark Blue: Very Good. UZ:

1262 Upper zone; DZ: Deep zone.

<table><thead><tr><th>Code</th><th>Sites</th><th>1-UZ</th><th>1-DZ</th><th>2</th><th>3-4-UZ</th><th>3-4-DZ</th><th>5</th><th>6</th><th>7</th><th>8</th><th>9a</th><th>9b</th><th>10</th><th>11</th><th>12a</th><th>12b</th><th>EBQI</th><th>Cir.</th></tr></thead><tbody><tr><td>01COU</td><td>La Couronne</td><td>0</td><td>0</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>4</td><td>2</td><td>4</td><td>3</td><td>0</td><td>0</td><td>0</td><td>2</td><td>2.88</td><td>0.44</td></tr><tr><td>02CAR</td><td>Carry</td><td>1</td><td>0</td><td>1</td><td>1</td><td>0</td><td>4</td><td>2</td><td>4</td><td>3</td><td>3</td><td>0</td><td>1</td><td>4</td><td>0</td><td>4</td><td>4.55</td><td>0.27</td></tr><tr><td>03PRA</td><td>Baie du Prado</td><td>1</td><td>1</td><td>1</td><td>2</td><td>1</td><td>2</td><td>1</td><td>2</td><td>3</td><td>4</td><td>1</td><td>2</td><td>0</td><td>2</td><td>4</td><td>4.34</td><td>0.46</td></tr><tr><td>04PLA</td><td>Planier</td><td>1</td><td>2</td><td>1</td><td>3</td><td>2</td><td>0</td><td>3</td><td>4</td><td>4</td><td>4</td><td>2</td><td>2</td><td>2</td><td>2</td><td>4</td><td>5.9</td><td>0.56</td></tr><tr><td>05PR</td><td>Passe de Riou</td><td>2</td><td>1</td><td>1</td><td>2</td><td>1</td><td>0</td><td>1</td><td>2</td><td>2</td><td>3</td><td>0</td><td>1</td><td>0</td><td>3</td><td>3</td><td>3.65</td><td>0.45</td></tr><tr><td>06SUG</td><td>Sugiton</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>0</td><td>1</td><td>1</td><td>4</td><td>1</td><td>0</td><td>3</td><td>2</td><td>1</td><td>1</td><td>3.30</td><td>0.42</td></tr><tr><td>07CC</td><td>Cap Canaille</td><td>1</td><td>1</td><td>0</td><td>1</td><td>1</td><td>4</td><td>3</td><td>4</td><td>3</td><td>1</td><td>0</td><td>0</td><td>2</td><td>1</td><td>1</td><td>3.92</td><td>0.58</td></tr><tr><td>08IVE</td><td>Île Verte</td><td>3</td><td>1</td><td>2</td><td>4</td><td>2</td><td>2</td><td>4</td><td>4</td><td>1</td><td>1</td><td>3</td><td>4</td><td>0</td><td>3</td><td>4</td><td>6.84</td><td>0.46</td></tr><tr><td>09EMB</td><td>Embiez</td><td>4</td><td>2</td><td>2</td><td>3</td><td>2</td><td>4</td><td>4</td><td>3</td><td>2</td><td>2</td><td>3</td><td>4</td><td>0</td><td>1</td><td>3</td><td>6.98</td><td>0.63</td></tr><tr><td>10AMP</td><td>Amphitria</td><td>0</td><td>1</td><td>0</td><td>1</td><td>1</td><td>0</td><td>2</td><td>4</td><td>3</td><td>3</td><td>1</td><td>0</td><td>0</td><td>1</td><td>0</td><td>3.09</td><td>0.58</td></tr><tr><td>11DF</td><td>Deux Frères</td><td>1</td><td>0</td><td>0</td><td>1</td><td>0</td><td>2</td><td>1</td><td>4</td><td>3</td><td>3</td><td>1</td><td>1</td><td>0</td><td>2</td><td>0</td><td>3.47</td><td>0.48</td></tr><tr><td>12TGR</td><td>Toulon Grande Rade</td><td>1</td><td>1</td><td>0</td><td>2</td><td>3</td><td>2</td><td>1</td><td>4</td><td>3</td><td>1</td><td>0</td><td>4</td><td>0</td><td>1</td><td>0</td><td>4.65</td><td>0.29</td></tr><tr><td>13FG</td><td>Fourmigue de Giens</td><td>1</td><td>2</td><td>2</td><td>3</td><td>1</td><td>0</td><td>3</td><td>4</td><td>3</td><td>1</td><td>1</td><td>3</td><td>0</td><td>3</td><td>2</td><td>5.52</td><td>0.41</td></tr><tr><td>14POR</td><td>Porquerolles Est</td><td>3</td><td>4</td><td>4</td><td>2</td><td>4</td><td>2</td><td>1</td><td>4</td><td>2</td><td>1</td><td>3</td><td>1</td><td>0</td><td>3</td><td>2</td><td>6.70</td><td>0.48</td></tr><tr><td>15HB</td><td>Baie d'Hyères</td><td>4</td><td>2</td><td>2</td><td>4</td><td>4</td><td>4</td><td>2</td><td>0</td><td>2</td><td>4</td><td>3</td><td>1</td><td>0</td><td>4</td><td>3</td><td>5.76</td><td>0.48</td></tr><tr><td>16BAG</td><td>Passe de Bagaud</td><td>4</td><td>4</td><td>4</td><td>4</td><td>4</td><td>4</td><td>1</td><td>3</td><td>2</td><td>1</td><td>2</td><td>1</td><td>2</td><td>4</td><td>1</td><td>7.15</td><td>0.52</td></tr><tr><td>17VAI</td><td>Vaisseau</td><td>4</td><td>2</td><td>4</td><td>4</td><td>4</td><td>0</td><td>3</td><td>4</td><td>3</td><td>3</td><td>1</td><td>4</td><td>0</td><td>0</td><td>3</td><td>7.53</td><td>0.39</td></tr><tr><td>18CAV</td><td>Cavalaire</td><td>1</td><td>3</td><td>1</td><td>2</td><td>2</td><td>4</td><td>1</td><td>4</td><td>3</td><td>0</td><td>1</td><td>3</td><td>0</td><td>4</td><td>1</td><td>5.63</td><td>0.27</td></tr><tr><td>19CT</td><td>Cap Taillat</td><td>4</td><td>2</td><td>1</td><td>2</td><td>1</td><td>4</td><td>1</td><td>0</td><td>2</td><td>2</td><td>3</td><td>4</td><td>2</td><td>4</td><td>1</td><td>5.21</td><td>0.41</td></tr><tr><td>20CAM</td><td>Cap Camarat</td><td>4</td><td>3</td><td>1</td><td>3</td><td>2</td><td>4</td><td>1</td><td>4</td><td>2</td><td>3</td><td>4</td><td>1</td><td>0</td><td>1</td><td>1</td><td>6.01</td><td>0.40</td></tr><tr><td>21PAM</td><td>Pampelonne</td><td>4</td><td>4</td><td>2</td><td>4</td><td>4</td><td>4</td><td>4</td><td>4</td><td>2</td><td>4</td><td>3</td><td>2</td><td>2</td><td>2</td><td>3</td><td>8.06</td><td>0.73</td></tr><tr><td>22ST</td><td>Saint Tropez</td><td>0</td><td>0</td><td>0</td><td>1</td><td>0</td><td>0</td><td>1</td><td>4</td><td>3</td><td>1</td><td>0</td><td>0</td><td>2</td><td>2</td><td>2</td><td>2.74</td><td>0.51</td></tr><tr><td>23SAR</td><td>Sardinaux</td><td>4</td><td>0</td><td>1</td><td>4</td><td>1</td><td>2</td><td>1</td><td>3</td><td>2</td><td>0</td><td>0</td><td>3</td><td>4</td><td>0</td><td>4</td><td>5.07</td><td>0.33</td></tr><tr><td>24DRA</td><td>Dramont</td><td>4</td><td>1</td><td>2</td><td>3</td><td>1</td><td>2</td><td>1</td><td>1</td><td>3</td><td>0</td><td>3</td><td>4</td><td>4</td><td>2</td><td>4</td><td>5.66</td><td>0.54</td></tr><tr><td>25AGA</td><td>Agay</td><td>1</td><td>1</td><td>1</td><td>2</td><td>1</td><td>0</td><td>1</td><td>4</td><td>1</td><td>1</td><td>3</td><td>0</td><td>0</td><td>4</td><td>4</td><td>4.03</td><td>0.33</td></tr><tr><td>26EST</td><td>Esterel</td><td>3</td><td>4</td><td>2</td><td>2</td><td>2</td><td>4</td><td>1</td><td>3</td><td>2</td><td>3</td><td>4</td><td>2</td><td>0</td><td>2</td><td>4</td><td>6.49</td><td>0.49</td></tr><tr><td>27TH</td><td>Théoule sur mer</td><td>1</td><td>0</td><td>0</td><td>2</td><td>1</td><td>2</td><td>0</td><td>0</td><td>3</td><td>3</td><td>1</td><td>0</td><td>0</td><td>1</td><td>2</td><td>2.05</td><td>0.43</td></tr><tr><td>28ANT</td><td>Cap Antibes</td><td>1</td><td>2</td><td>1</td><td>2</td><td>1</td><td>4</td><td>0</td><td>2</td><td>0</td><td>3</td><td>1</td><td>3</td><td>0</td><td>4</td><td>4</td><td>4.65</td><td>0.25</td></tr><tr><td>29VIL</td><td>Villefranche sur mer</td><td>1</td><td>0</td><td>1</td><td>2</td><td>1</td><td>2</td><td>1</td><td>4</td><td>4</td><td>1</td><td>2</td><td>2</td><td>2</td><td>3</td><td>4</td><td>5.00</td><td>0.54</td></tr></tbody></table>

1263

1264
<figure><img src="image_2.png" /></figure>

1265

1266

1267

1268

Figure 1. Conceptual functional model of the Coastal Detrital Bottom Ecosystem. Arrows correspond to a flux of organic matter between boxes. Light grey boxes are not assessed directly. *See corresponding paragraph for more details about Carbon sink.

<figure><img src="image_3.png" /></figure>

1269

1270

Figure 2. Study area along the French Mediterranean coast and location of the 29 sampling sites.
<figure><img src="image_4.png" /></figure>

1271

1272 Figure 3. Diagram of the Biocube device. The pictures on the right show different types of CDB

1273 sampled on photoquadrats.

<figure><img src="image_5.png" /></figure>

1274

1275 Figure 4. Principal Component Analysis. Sampling sites are coloured according to their EBQI notation.

1276 Boxes descriptors are projected in light grey. Red: Poor; Yellow: Bad; Green: Intermediate; Blue:

1277 Good; Dark Blue: Very Good.

1278
<figure><img src="image_6.png" /><figcaption>Figure 5. Spearman rank correlation between the fifteen descriptors related to ecosystem boxes of the coastal detrital bottoms. The number in bold is the correlation coefficient R. \*: p < 0.05; \*: p < 0.01; \*: p < 0.001. Blue: positive correlation; Red: Negative correlation.</figcaption></figure>

1279
1280
1281
1282
<figure><img src="image_7.png" /><figcaption>Figure 6. Scores of EBQI and Circularity for the 29 sites. Red: Poor; Yellow: Bad; Green: Intermediate; Blue: Good; Dark Blue: Very Good.</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>Figure 7. Box plots showing EBQI notation (left) and circularity value (right) according management level. The black crossbar corresponds to the mean EBQI notation, the grey rectangle corresponds to the standard error, the vertical bars correspond to the 95% confidence interval.</figcaption></figure>

1283

1284

1285

1286

1287

1288

1289

1290
1291

<figure><img src="image_9.png" /></figure>

1292

<figure><img src="image_10.png" /></figure>

1293

Figure 8. Robustness of the EBQI with regard to the Ecological status per box. Sampling sites are sorted in ascending order according to the EBQI notation from left to right. In order to test the effect of the status per box on the EBQI (robustness), status values have been randomly perturbed (above, ±1; below, ±2) 25% (left) and 100% (right) of probability; 1000 iterations were performed. The change of the EBQI notation (bad through very good) of a site, for a given iteration, is shown by the colour of the new class in which it falls). Red: Poor; Yellow: Bad; Green: Intermediate; Blue: Good; Dark Blue: Very Good.

1294

1295

1296

1297

1298

1299

1300

1301

<figure><img src="image_11.png" /></figure>

1302

1303

1304

1305

1306

1307

1308

1309

Figure 9. Robustness of the EBQI with regard to the weighting per box. Sampling sites are sorted in ascending order according to the EBQI notation from left to right. In order to test the effect of the weighting per box on the EBQI (robustness), status values have been randomly perturbed (above, ±1; below, ±2) 25% (left) and 100% (right) of probability; 1000 iterations were performed. The change of the EBQI notation (bad through very good) of a site, for a given iteration, is shown by the colour of the new class within which it falls. Red: Poor; Yellow: Bad; Green: Intermediate; Blue: Good; Dark Blue: Very Good.