# New record of the crab Planes marinus Rathbun, 1914 in the eastern English Channel

Camille Hennion, Jean-Luc Bourgain, Shagnika Das, Nicolas Spilmont, Emilie

Moisez, Laurent Seuront

► To cite this version:

Camille Hennion, Jean-Luc Bourgain, Shagnika Das, Nicolas Spilmont, Emilie Moisez, et al. New record of the crab Planes marinus Rathbun, 1914 in the eastern English Channel. BioInvasions Records, 2025, 14 (1), pp.233-249. 10.3391/bir.2025.14.1.18. hal-05077708

HAL Id: hal-05077708

https://hal.science/hal-05077708v1

Submitted on 21 May 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
Research Article

# New record of the crab *Planes marinus* Rathbun, 1914 in the eastern English Channel

Camille Hennion<fnref n="1" />, Jean-Luc Bourgain<fnref n="2" />, Shagnika Das<fnref n="3" />, Nicolas Spilmont<fnref n="1" />, Emilie Moisez<fnref n="1" /> and Laurent Seuront<fnref n="1" />,<fnref n="4" />,<fnref n="5" />

Corresponding author: Camille Hennion (camille.hennion@univ-lille.fr)

**Citation:** Hennion C, Bourgain JL, Das S, Spilmont N, Moisez E, Seuront L (2025) *New record of the crab *Planes marinus* Rathbun, 1914 in the eastern English Channel. *BioInvasions Records* 14(1): 233–249, https://doi.org/10.3391/bir.2025.14.1.18

**Received:** 15 October 2024

**Accepted:** 16 January 2025

**Published:** 29 March 2025

**Handling editor:** Enrique Gonzalez Ortegon

**Thematic editor:** Amy Fowler

**Copyright:** © Hennion et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0).

OPEN ACCESS

## Abstract

Over the last few decades, the introduction of non-indigenous species (NIS) has become a growing concern for the scientific community and international agencies. Maritime transport, in particular ballast waters and hull fouling, as well as floating marine debris, are the main vectors of these introductions. A striking example of NIS introduction occurred after the Ciaran and Domingos storms in November 2023, when a piece of wood, covered in living *Lepas anatifera* barnacles, washed up on the beach at Boulogne-sur-Mer along the French shores of the eastern English Channel. Ten crabs of the genus *Planes* were found, including three belonging to the species *Planes marinus*, which to the best of our knowledge was never reported in the north-east Atlantic and on the French coast in particular. *Planes marinus* is a species known mainly from the Pacific, but its growing presence in other oceans highlights the importance of marine debris as a dispersal vector. In this context, the present work highlights the potential impact of extreme weather events, amplified by climate change, on the distribution of NIS, as well as the need to monitor stranded debris to better understand and manage these introductions, which is crucial to the preservation of European marine ecosystems.

**Key words:** floating debris, brachyuran crabs, extreme weather events, morphological characteristics, non-indigenous species.

## Introduction

Over the last decades, studies on the introduction of non-indigenous species (NIS) have gained considerable attention in the scientific community (e.g. Hulme 2009; Massé et al. 2023) and for international governmental agencies (IPBES 2019), which enabled a better understanding of the effects these species on ecosystems and their dynamics (Diagne et al. 2021). The most significant factor responsible for the introduction of new species in any type of habitat is the transport and logistics industry (Donelan et al. 2022; European Environment Agency 2023). Although trade and transport represent a high ecological coast (Jägerbrand et al. 2019; Das et al. 2020, 2023), they are highly

<footnote n="1">¹Laboratoire d'Océanologie et de Géosciences, Université de Lille, CNRS, Université du Littoral Côte d'Opale, IRD, UMR 8187, France</footnote>

<footnote n="2">²Phoques d'Opale, 16 rue Libert, 62480, Le Portel, France</footnote>

<footnote n="3">³Centre for Marine Science and Technology, Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida 201301, India</footnote>

<footnote n="4">⁴Department of Marine Resources and Energy, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108-8477 Japan</footnote>

<footnote n="5">⁵Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140 South Africa</footnote>
economically driven with an average turnover of 25 trillion US$ (UNCTAD 2024), which makes them a cornerstone of the global economic system. Multiple vectors of introduced species have emerged through maritime transport, mainly ballast waters and hull fouling (Williams et al. 2013; Zettler 2021). In addition, the aquaculture industry, the use of live feed, the trade of ornamental species, yachting, recreational fishing activities (Goulletquer 2016) and, more recently, floating debris (Póvoa et al. 2021) have all been acknowledged to contribute to the introduction of NIS. Marine debris originate from multiple sources such as land-based, ocean-based, or extreme events (NOAA 2024) and are composed of both natural and anthropogenic materials, which are often observed drifting along the coast and/or carried from the land via rivers and waterways (Galgani et al. 2015; Aragaw 2021). The bulk proportion of these floating debris are of anthropogenic origin; natural debris such as macroalgae, plants or animals, are marginal (Arnaud et al. 1976; Highsmith 1985; Edgar 1987). Amongst the anthropogenic waste, plastic is the key example of marine debris that is now ubiquitous in the world ocean, due to the lightweight nature of this material, hence its ability to float and drift (Barnes 2002; Bravo et al. 2011; Gündoğdu et al. 2017; Mghili et al. 2023; Rech et al. 2023).

Specifically, floating marine debris are now considered as one of the major vectors for transporting species (Kano et al. 2013; Gustavson et al. 2020; Mantelatto et al. 2020; Kannan et al. 2023). The biota found on these floating materials, sometimes also referred to as “floating islands” (Jokiel 1990), is typically an assemblage of many taxonomic groups and lineages, with an average of 387 taxa that can be transported over considerable distances by floating anthropogenic litter (Kiessling et al. 2015). Some organisms, such as the Crustacean Cirripeds *Lepas* sp., the so-called Goose barnacles, are well known for colonizing any type of floating debris (Boëtius 1952; Thiel and Gutow 2005) and provide shelter for several species, such as other cirripeds, bryozoans, mollusks, polychaetas or crustacean decapods (Póvoa et al. 2021).

Given its unique geographical location, France is the only European country with a coastline running along the North Sea, the English Channel, the Atlantic Ocean and the Mediterranean Sea (Noël 2002). This location, at the crossroads of Europe, implies an intense maritime traffic and diverse influx of floating objects. Notably, the eastern English Channel is one of the most important commercial and passenger transit routes globally, with nearly 500 vessels crossing the Dover Straight daily (UK Government 2024). The extent of this maritime route often entails the arrival of introduced species in the eastern English Channel through ballast waters and biofouling (Goulletquer et al. 2002; Dewarumez et al. 2011; Massé et al. 2023). Marine floating litter plays a significant role in the introduction of new species given the stranding of a wide range of debris, that are driven by currents
<figure><img src="image_2.png" /><figcaption>**Figure 1.** Wooden marine debris beached in Boulogne sur Mer (A) and covered with the barnacle *Lepas anatifera* (B). © Camille Hennion.</figcaption></figure>

and winds, along with extreme events such as storms (Menicagli et al. 2022). The Ciaran and Domingos storms which occurred between 1st and 4th November 2023 are epitome instances of these events which typically impacted the western coast of France. This catastrophic event was considered as the 5th most devastating storm affecting the French territory, that induced numerous damages (France Assureurs 2023). In particular, this led to a large amount of debris being transported to the English Channel from rivers and the sea, which then washed up on the coast. Although the management of non-native species has become a major concern over the last few decades (Pyšek and Richardson 2010), studies on floating debris and their associated organisms are still critically scarce.

In this context, following the Ciaran and Domingos storms, on November 19, 2023 a large piece of wood (ca. 6 m long and 50 cm wide) was found on the beach of Boulogne-sur-Mer ((50°43'55.2"N, 1°35'35.2"E; Figure 1A). It was entirely covered by a dense living bed of the goose barnacle *Lepas* (*Lepas*ianatifera Linnaeus, 1758 (Figure 1B), where 10 alive Brachyuran crabs belonging to the Grapsidae family and to the genus *Planes* were found. Here, we extensively describe the morphometrics of the 10 collected specimens and unambiguously show that some belong to the species *Planes marinus* Rathbun, 1914.

**Materials and methods**

*Identification of Planes species*

The 10 sampled crabs were taken back to the laboratory and stored in 70% ethanol until further analysis. Based on the morphological characteristics reported for the two species of *Planes*, i.e. *Planes minutus* (Linnaeus, 1758)
<figure><img src="image_3.png" /><figcaption>**Figure 2.** Carapace measurements of *Planes marinus* (A) and *Planes minutus* (B). CL: Carapace Length; CW: Carapace Width. © Camille Hennion.</figcaption></figure>

and *P. marinus* (Chace 1951), four morphological features were consistently investigated on the 10 individuals (9 males and 1 female): the carapace, the chelipeds, the walking legs and the pleon. The carapace dimensions, i.e. length (CL) and width (CW; Figure 2), were precisely measured using a digital caliper (Garant 412780_150; resolution of 0.01 cm) and the ratio between these
<figure><img src="image_4.png" /><figcaption>**Figure 3.** Three last segments of 2^nd^ Walking Leg (LWL2) of *Planes marinus* (A) and *Planes minutus* (B). © Camille Hennion.</figcaption></figure>

two values (CL/CW) was calculated. The shape of the carapace and the striated branchial region of *Planes* sp. were also carefully noted. Different shapes can be found: subquadrate (rather square shape), trapezoidal or laterally convex. The length of the three last segments of each pair of 2^nd^ walking leg (LWL2) was measured after dissection (Figure 3) to obtain the proportion with the carapace length (LWL2/CL). All these measurements were conducted on images taken from a stereomicroscope (Olympus SZX16) and were quantified with ImageJ software (Schneider et al. 2012) with the measurements expressed in millimetres.

As firstly described by Chace (1951) and subsequently confirmed (Arnaud et al. 1972; Lemaitre 1999; Spivak and Bas 1999; Prado and de Melo 2002), the male pleon is another criteria of discrimination between the two species. Hence we investigated the ratio between the total length of the four distal pleonites (L4DP) and the width of the fourth one (W4P; Figure 4) through careful microscopic observations and accurate quantification using ImageJ software. The L4DP was taken from the middle of the pleon, representing the maximal length and the W4P was taken in the middle of the pleonite, representing the longer value following Chace (1951). Along with these measurements, the shape of the telson was also noted under the stereomicroscope. Two different shapes of telson are found in this species; narrowly triangular and laterally convex (narrowly rounded at the sides).
<figure><img src="image_5.png" /><figcaption>**Figure 4.** Pleon measurements of *Planes marinus* (A) and *Planes minutus* (B). L4DP: Length of the 4 distal pleonites; W4P: Width of the 4th pleonite. © Camille Hennion.</figcaption></figure>

## Statistical analyses

Due to the limited number of replicates (N = 10), non-parametric tests were used throughout this work. Specifically, differences in carapace ratio (CL/CW), second walking legs and carapace length ratio (LWL2/CL) and male pleon ratio (L4DP/W4P) were tested through a Mann-Whitney U test (Zar 2010). All statistical analyses were carried out using R-Studio (version 4.4.1).

## Results

### Morphological analysis

Out of the 10 sampled crabs, we identified 7 *P. minutus* (one female and six males) and 3 *P. marinus* (all males). Carapace length and width measurements were compared for males only, since only one female was collected. The CL/CW ratio showed a significant difference (*p* < 0.01) between *P. marinus* (1.03 ± 0.02; mean ± standard deviation) and *P. minutus* (1.07 ± 0.01; Table 1).

The carapace shape was laterally convex in *P. minutus*, and more subquadrate in *P. marinus* (Chace 1951; Spivak and Bas 1999) (Table 2). The analysis of this single morphological specificity is, however, not sufficient to differentiate the two species (Chace 1951). On the surface of the carapace, a clear striation was observed in *P. marinus* while the carapace of *P. minutus* was slightly striated (Spivak and Bas 1999; Table 2). More specifically, previous studies comparing the chelipeds of the two species showed a noticeable downward bending of the fixed finger only in *P. minutus* (Arnaud et al. 1972; Chace 1951; Table 2). All the crabs examined in this study exhibited a downward bending of the fixed finger (Table 2), hence this
<table><caption>**Table 1.** Morphological features measured for each crab individual. CL: Carapace Length; CW: Carapace Width. LWL2: Length of 2nd Walking Leg; L4DP: Length of 4 Distal Pleonites; W4P: Width of the 4th Pleonite.</caption><thead><tr><th>Specimen</th><th>Sex</th><th>CL (cm)</th><th>CW (cm)</th><th>CL/CW</th><th>LWL2 (cm)</th><th>LWL2/CL</th><th>L4DP (cm)</th><th>W4P (cm)</th><th>L4DP/W4P</th></tr></thead><tbody><tr><td rowspan="2">P. minutus-1</td><td rowspan="2">M</td><td rowspan="2">1.94</td><td rowspan="2">1.87</td><td rowspan="2">1.04</td><td>1.50</td><td>0.77</td><td rowspan="2">0.802</td><td rowspan="2">0.713</td><td rowspan="2">1.12</td></tr><tr><td>1.54</td><td>0.79</td></tr><tr><td rowspan="2">P. minutus-2</td><td rowspan="2">M</td><td rowspan="2">1.62</td><td rowspan="2">1.58</td><td rowspan="2">1.03</td><td>1.25</td><td>0.77</td><td rowspan="2">0.647</td><td rowspan="2">0.561</td><td rowspan="2">1.15</td></tr><tr><td>1.23</td><td>0.76</td></tr><tr><td rowspan="2">P. minutus-3</td><td rowspan="2">M</td><td rowspan="2">1.79</td><td rowspan="2">1.72</td><td rowspan="2">1.04</td><td>1.37</td><td>0.77</td><td rowspan="2">0.744</td><td rowspan="2">0.661</td><td rowspan="2">1.13</td></tr><tr><td>1.39</td><td>0.78</td></tr><tr><td rowspan="2">P. minutus-4</td><td rowspan="2">M</td><td rowspan="2">1.9</td><td rowspan="2">1.92</td><td rowspan="2">0.99</td><td>1.39</td><td>0.73</td><td rowspan="2">0.8</td><td rowspan="2">0.694</td><td rowspan="2">1.15</td></tr><tr><td>1.48</td><td>0.78</td></tr><tr><td rowspan="2">P. minutus-5</td><td rowspan="2">M</td><td rowspan="2">1.69</td><td rowspan="2">1.64</td><td rowspan="2">1.03</td><td>1.32</td><td>0.78</td><td rowspan="2">0.693</td><td rowspan="2">0.615</td><td rowspan="2">1.13</td></tr><tr><td>1.25</td><td>0.74</td></tr><tr><td rowspan="2">P. minutus-6</td><td rowspan="2">F</td><td rowspan="2">1.47</td><td rowspan="2">1.35</td><td rowspan="2">1.09</td><td>1.15</td><td>0.79</td><td rowspan="2">NA</td><td rowspan="2">NA</td><td rowspan="2">NA</td></tr><tr><td>1.14</td><td>0.77</td></tr><tr><td rowspan="2">P. minutus-7</td><td rowspan="2">M</td><td rowspan="2">1.87</td><td rowspan="2">1.81</td><td rowspan="2">1.03</td><td>1.55</td><td>0.83</td><td rowspan="2">0.708</td><td rowspan="2">0.59</td><td rowspan="2">1.20</td></tr><tr><td>1.59</td><td>0.85</td></tr><tr><td rowspan="2">P. marinus-1</td><td rowspan="2">M</td><td rowspan="2">1.99</td><td rowspan="2">1.86</td><td rowspan="2">1.07</td><td>1.40</td><td>0.70</td><td rowspan="2">0.746</td><td rowspan="2">0.689</td><td rowspan="2">1.08</td></tr><tr><td>1.39</td><td>0.70</td></tr><tr><td rowspan="2">P. marinus-2</td><td rowspan="2">M</td><td rowspan="2">1.96</td><td rowspan="2">1.85</td><td rowspan="2">1.06</td><td>1.38</td><td>0.71</td><td rowspan="2">0.724</td><td rowspan="2">0.669</td><td rowspan="2">1.08</td></tr><tr><td>1.42</td><td>0.73</td></tr><tr><td rowspan="2">P. marinus-3</td><td rowspan="2">M</td><td rowspan="2">2</td><td rowspan="2">1.86</td><td rowspan="2">1.08</td><td>1.43</td><td>0.71</td><td rowspan="2">0.778</td><td rowspan="2">0.736</td><td rowspan="2">1.06</td></tr><tr><td>1.36</td><td>0.68</td></tr></tbody></table>

<table><caption>**Table 2.** Morphological features of *P. minutus* and *P. marinus*, adapted and completed from Chace, 1951 with the data from this work. New or updated data are written in bold.</caption><thead><tr><th rowspan="2"></th><th rowspan="2">Characters</th><th colspan="2">Features of Chace (1951)</th><th colspan="2">Features of the present study</th></tr><tr><th>Planes minutus</th><th>Planes marinus</th><th>Planes minutus</th><th>Planes marinus</th></tr></thead><tbody><tr><td rowspan="4">Carapace</td><td>Length (cm)</td><td>0.37 to 1.9</td><td>0.5 to 1.9</td><td><strong>1.47 to 1.94</strong></td><td><strong>1.96 to 2.00</strong></td></tr><tr><td>Width (cm)</td><td>NA</td><td>NA</td><td><strong>1.35 to 1.92</strong></td><td><strong>1.85 to 1.86</strong></td></tr><tr><td>Proportions (L/W)</td><td>0.91 to 1.12</td><td>1.07 to 1.16</td><td><strong>0.99 to 1.09</strong></td><td><strong>1.06 to 1.07</strong></td></tr><tr><td>Shape (adults only)<br>Surface of branchial<br>regions</td><td>Laterally convex<br>Faintly striated laterally</td><td>Subquadrate<br>Distinctly striated<br>laterally</td><td>Laterally convex<br>Faintly striated<br>laterally</td><td>Subquadrate<br>Distinctly striated<br>laterally</td></tr><tr><td>Chelipeds</td><td>Granulation and bending<br>of the fixed finger</td><td>With prominent sharp<br>granules near lower<br>margin, bent sharply<br>downward, especially in<br>males</td><td>Few inconspicuous<br>granules near lower<br>margin, not noticeably<br>bent downward</td><td>Granulated and<br>slightly bent<br>downward</td><td><strong>Slightly<br>Granulated and<br>slightly bent<br>downward</strong></td></tr><tr><td rowspan="3">Walking<br>legs</td><td>Shape</td><td>Long, slender and<br>flattened</td><td>Rather short, stout and<br>not noticeably flattened</td><td>Long and slender</td><td>Short and stout</td></tr><tr><td>Length of 3 distal<br>segments of 2nd walking<br>legs pair (cm)</td><td>NA</td><td>NA</td><td><strong>1.47 to 1.94</strong></td><td><strong>1.36 to 1.43</strong></td></tr><tr><td>Proportion of length of 3<br>distal segments of second<br>pair to carapace length</td><td>0.83 to 1.07</td><td>0.77 to 0.99</td><td><strong>0.73 to 0.85</strong></td><td><strong>0.68 to 0.72</strong></td></tr><tr><td rowspan="4">Male Pleon</td><td>Shape of the Telson</td><td>Rather narrowly<br>triangular</td><td>Broadly triangular</td><td>Triangular but<br>slightly laterally<br>convex</td><td>Triangular</td></tr><tr><td>Length of the four distal<br>pleonites (cm)</td><td>NA</td><td>NA</td><td><strong>0.65 to 0.80</strong></td><td><strong>0.72 to 0.78</strong></td></tr><tr><td>Width of the fourth<br>pleonite (cm)</td><td>NA</td><td>NA</td><td><strong>0.56 to 0.71</strong></td><td><strong>0.67 to 0.74</strong></td></tr><tr><td>Proportion of length of the<br>four distal pleonites to<br>width of the fourth<br>pleonite (L4DP/W4P)</td><td>1.24</td><td>1.08</td><td><strong>1.12 to 1.15</strong></td><td><strong>1.06 to 1.08</strong></td></tr></tbody></table>

feature could not be considered as discriminatory to differentiate the two species. However, the morphometry of the second pair of walking legs, i.e. the ratio between the length of the three last segments and carapace length
<figure><img src="image_6.png" /><figcaption>**Figure 5.** Locations of previous observations of *Planes marinus*. Triangle: type location; square: crabs found living on/in Sea Turtles; circle: other observations; star: this study.</figcaption></figure>

(LWL2/CL), showed highly significant statistical differences (*p* < 0.01) with higher values in *P. minutus* (0.78 ± 0.03; mean ± standard deviation) than in *P. marinus* (0.70 ± 0.02). Finally, the ratio between the total length of the four distal segments and the width of the fourth one (L4DP/W4P) showed significantly higher values (*p* < 0.01) in *P. minutus* (1.15 ± 0.02) than in *P. marinus* (1.07 ± 0.01). The shape of the telson was more triangular in *P. marinus*, whereas in *P. minutus* the telson was slightly triangular and laterally convex (Table 2).

Discussion

*Worldwide distribution of Planes marinus*

The first documentation of *P. marinus* was in California (Rathbun 1914), and the species was subsequently reported in the North-Western coast of America (Ward 1939; Chace 1951), Canada (Hart 1958) and Hawaii (Chace 1951; Edmondson 1959) (Figure 5; Table 3). This species eventually spread to the Eastern coasts of the Pacific Ocean in New Zealand and Kermadec Islands (Dell 1963, 1964; Wear 1970), the Indian Ocean with observations in Madagascar (Crosnier 1965) and in Amsterdam Island (Arnaud et al. 1972). *Planes marinus* was also reported along Southeast Asian coasts, such as in Japan and China from 1977 (Takeda and Kurata 1977; Dai and Yang 1991; Kepel et al. 2002). In the Atlantic Ocean, *P. marinus* has been reported in areas ranging from the East coasts of South America (Spivak and Bas 1999; Prado and de Melo 2002) and North America (Questel 2019), on islands in the central Atlantic Ocean (Chace 1966; Holthuis and Sivertsen 1967; Tavares and Mendonça 2022) and the Southern Atlantic Ocean (Chace 1966) in St Helena and Tristan Da Cunha Island (Holthuis and Sivertsen 1967).
<table><caption>**Table 3.** Details of previous observations of *Planes marinus*. Geo-referenced data are provided in the Supplementary material Table S1.</caption><thead><tr><th>Geographical zone</th><th>Location</th><th>Reference</th><th>Remarks</th></tr></thead><tbody><tr><td rowspan="10">Eastern Pacific Ocean</td><td>Low California</td><td>Rathbun 1914, 1918</td><td>Type Locality</td></tr><tr><td>Off California</td><td>Ward 1939</td><td rowspan="2">Japanese mine</td></tr><tr><td>Oregon, Lincoln beach</td><td>Chace 1951</td></tr><tr><td>Hawai, Mokapu</td><td>Chace 1951; Edmondson 1959;</td><td rowspan="2">Clinging to the net of a large Japanese glass float</td></tr><tr><td>Hawai, Oahu</td><td>Pfaller et al. 2019</td></tr><tr><td>Vancouver Island, Canada</td><td>Hart 1958</td><td rowspan="2">found on propylene rope</td></tr><tr><td>Northern Chile</td><td>Lemaitre 1999</td></tr><tr><td>West coast of America to Hawaiian Islands</td><td>Frick et al. 2011</td><td rowspan="2">Sympatry with sea Turtles</td></tr><tr><td>Great Pacific Garbage Patch</td><td>Pfaller et al. 2019</td></tr><tr><td rowspan="7">Western Pacific Ocean</td><td>New Zealand, Omaio Bay</td><td>Dell 1963</td><td>Collected from a thick layer of goose barnacles attached to a Japanese glass fishing float cast</td></tr><tr><td>Kermadec Islands, Denham Bay Beach</td><td>Dell 1964</td><td>Presumably collected on the beach, with floating debris</td></tr><tr><td>New Zealand, Lyall Bay, Wellington</td><td>Wear 1970</td><td>Found on a rope and barnacle-covered glass fishing float</td></tr><tr><td>Japan, Ogasawara Islands</td><td>Takeda and Kurata 1977</td><td>Collected among volcanic debris</td></tr><tr><td>South China Sea, Xisha Island</td><td>Dai and Yang 1991</td><td rowspan="2">collected on a buoy overgrown with <i>Mytilus galloprovincialis</i>.</td></tr><tr><td>Furugelm Island, Sea of Japan</td><td>Kepel et al. 2002</td></tr><tr><td>Northern Mariana Islands</td><td>Pfaller et al. 2019</td><td>Flotsam</td></tr><tr><td rowspan="3">Indian Ocean</td><td>Western coast of Australia</td><td>Pfaller et al. 2019</td><td>Flotsam</td></tr><tr><td>Madagascar</td><td>Crosnier 1965; Pfaller et al. 2019</td><td rowspan="2">collected from a beached buoy covered with <i>Lepas sp.</i></td></tr><tr><td>Amsterdam Island</td><td>Arnaud et al. 1972</td></tr><tr><td rowspan="8">Western Atlantic Ocean</td><td>Argentina, Mar Chiquita</td><td>Spivak and Bas 1999</td><td>Collected from a piece of stranded rope</td></tr><tr><td>Brasil, Sao Paulo, Alcatraze Islands</td><td rowspan="2">Prado and de Melo 2002</td><td rowspan="2"></td></tr><tr><td>Brasil, Santa Catarina</td></tr><tr><td>Brasil, Rio Grande do Sul</td><td></td><td></td></tr><tr><td>Brasilian coast</td><td></td><td></td></tr><tr><td>St. Bathelemy</td><td>Questel 2019</td><td>Flotsam/Sea Turtles</td></tr><tr><td>Florida, USA</td><td>Pfaller et al. 2019</td><td>Flotsam/Sea Turtles</td></tr><tr><td>St. Martin</td><td>Pfaller et al. 2019</td><td>On washed log, at low tide</td></tr><tr><td>Trindade Island, Brasil</td><td>Tavares and Mendonça 2022</td><td></td></tr><tr><td rowspan="3">South Atlantic Ocean</td><td>St. Helena Island - Northeast coast</td><td>Chace 1966</td><td>collected from a drifting Kelp</td></tr><tr><td>St. Helena Island - Rupert's Bay</td><td rowspan="2">Holthuis and Sivertsen 1967</td><td>collected from a buoy</td></tr><tr><td>Tristan Da Cunha Island</td><td></td></tr><tr><td>North Atlantic Ocean</td><td>France, Boulogne sur Mer</td><td>Present study</td><td>collected from a wooden debris, living on <i>Lepas anatifera</i></td></tr></tbody></table>

In addition to the above sites, *P. marinus* was also recorded in Western Australia and Florida (Table 3 and Figure 5) in the year 2019 (Pfaller et al. 2019). In this context, our observations of *P. marinus* on a wooden debris beached along the French shores of the eastern English Channel represent the first record in the North-East Atlantic Ocean.

## A short history of the classification of *Planes* species

Crabs from the *Planes* genus are also known as Colombus crabs or oceanic crabs (Lemaitre 1999), with a worldwide distribution as described above. This genus initially included two species, *Planes cyaneus* and *Planes minutus*. Later *P. marinus*, initially associated to the genus *Pachygrapsus*, was included in the genus *Planes*. In addition, according to Worms (WoRMS Editorial Board 2024), *P. cyaneus* was described as a synonym of *P. minutus*, based on their morphometric features.
*Planes marinus* was initially described by Rathbun (1914), which was subsequently shifted to *Pachygrapsus* by Chace (1951), based on criteria such as the absence of natatory fringe of hairs on propodi of the first three pairs of walking legs. However, it was finally redefined as *Planes* spp. by Chace (1966), validating the first description of Rathbun (1914) as *Planes marinus*, based on the fact that specimens analyzed were missing the natatory fringe, a feature that was observed in other specimens (Dell 1963). These crabs are exclusively pelagic (Bouvier 1940; Edmondson 1959; Hart 1963) and occur on a range of floating object and debris (Thiel and Gutow 2005). They can be found on inorganic debris such as plastic (Dellinger et al. 1997; Lemaitre 1999), rope (Spivak and Bas 1999), buoys (Arnaud et al. 1972; Kepel et al. 2002) or wood (Crozier 1918; Tavares and Mendonça 2022), but also in association with various species of sea turtles from different regions such as *Lepidochelys olivacea* (Eschscholtz, 1829) from Chile (Miranda and Moreno 2002) and the Pacific Coast of Mexico (Díaz et al. 1992; Frick et al. 2011), *Caretta caretta* (Linnaeus, 1758) from the Southern Atlantic (Davenport 1994; Carranza et al. 2003; Frick et al. 2004), North Atlantic (*field observations*) and/or Mediterranean Sea (Gaglioti and Mazzella 2021), Northwestern Indian Ocean (Yaghmour and Al Naqbi 2020) and *Chelonia mydas* (Linnaeus, 1758) from the Eastern Pacific (Wicksten and Behrens 2000). *Planes* species were also found on floating macroalgal invasive species, e.g. *Sargassum* spp. (Rathbun 1918; Bouvier 1940; Chace 1951; Geiselman 1983).

## Morphology of Planes marinus

The scientific literature abounds with morphological descriptions of *P. marinus* and its differentiation with *P. minutus* (Chace 1951; Crosnier 1965; Lemaitre 1999; Prado and de Melo 2002). The present study reports that the carapace of *P. marinus* is significantly different from that of *P. minutus*, with the latter having comparable length and width, while *P. marinus* is distinguished by a wider carapace (i.e. lower CL/CW ratio). This difference was observed by Chace (1951), who found the carapace of *P. marinus* to be 1.07–1.16 times wider, though Spivak and Bas (1999) stated that it was 1.08–1.25 times wider. It is notable, however, that the juvenile stages of *P. minutus* have a subquadrate carapace before becoming laterally convex, whereas the carapace of *P. marinus* is subquadrate at all ages (Chace 1951).

Striation is also clearly visible on the branchial surfaces of *P. marinus*, although this detail is less pronounced in *P. minutus*. The presence of the striation was also noted by Rathbun (1914) when describing the species and was later supported by other studies (Chace 1951; Crosnier 1965; Lemaitre 1999; Prado and de Melo 2002).

Another criteria to differentiate between the two *Planes* species is the chelipeds. Chace (1951) and later Dell (1963), Arnaud et al. (1972), Lemaitre
(1999) and Prado and de Melo (2002) described that *P. marinus* specimens showed a fixed finger not noticeably bent downward, compared with *P. minutus*, which has a distinct downward bending. However, in our study, we observed a downward bending in all the crabs analysed which renders this identifying feature inexact, lacking precision.

The walking legs of *P. marinus*, as described by Rathbun (1914), are short and broad. Further investigating the differences between the two species, Chace (1951) showed that the relationship between the length of the three distal segments of the second walking leg and the length of the carapace is higher in *P. minutus* than in *P. marinus*. In this study, we observed a significant difference between these ratios in the two species, in which *P. minutus* showed a ratio of 0.78 ± 0.03 and *P. minutus* a ratio of 0.70 ± 0.02. Chace (1951) also concluded that this ratio is undoubtedly the most useful detail for differentiating these two species.

Finally, previous observations of *P. marinus* males showed, a triangular pleon with a broad basal part (Chace 1951; Arnaud et al. 1972; Lemaitre 1999; Prado and de Melo 2002). Crosnier (1965) observed that the 6th segment is longer than the 5th. In this study, Chace (1951) and Spivak and Bas (1999) was followed and the ratio between the length of the 4 distal pleonites and the width of the 4th one was taken into consideration. According to Chace (1951) and Spivak and Bas (1999), this ratio is close to 1.08, which is close to the ratio found in this study (1.07 ± 0.01). Furthermore, a significant difference was noted between *P. minutus* (1.15 ± 0.02) and *P. marinus* (1.07 ± 0.01). Morphological characteristics provide a reliable and well-established method to study and distinguish new species records, particularly those closely related. Incorporating molecular techniques such as DNA barcoding can further enhance the accuracy and robustness of these identifications (Jara and Jaramillo 1979).

### Occurrence of Non-Indigenous Species through floating debris

The introduction of Non-Indigenous Species (NIS), relying on single and/or multi introduction vectors (Carlton and Ruiz 2015), is a source of ever-increasing concern and is partially controlled through massive regulations and managements. Ballast waters, considered as the main introduction vector for marine NIS, is nowadays strictly controlled at the international level, following the International Maritime Organizations' Ballast Water Management Convention (International Maritime Organization 2004). The use of alien species in aquaculture in EU is managed since 11th June 2007 through the Barring Council Regulation Act (EC) No 708/2007 (Council of the European Union 2007), but concerning hull biofouling, there is currently no regulation in place (Massé et al. 2023). Marine debris, considered as an emerging vector, remain poorly assessed (Carlton and Ruiz 2015), despite the fact that the number of debris, most of which is
plastic (i.e. 75%; Napper and Thompson 2020), has been increasing since
the 1970s (Jambeck et al. 2015). The release of debris into the seas and
oceans can sometimes be very significant, particularly during extreme
events, such as the tsunami caused by the earthquake that hit Japan in 2011
which released millions of diverse fragments of floating objects into the Pacific
Ocean (JTMD: Japan Tsunami Marine Debris) (Shimada 2016; Carlton et
al. 2017). Carlton et al. (2017) state that 289 species of living animals were
observed for the first time on the West American coast following this
Tsunami, on the JTMD. Other processes, such as waves and currents have
also been acknowledged as major drivers of beaching marine debris,
especially in the North-East Atlantic Ocean, which is considered as an
important area for beaching, given the influence of the North-Atlantic drift
(Bosi et al. 2021). Recent studies have modelled the potential path of
floating debris and showed that it may cross the Atlantic Ocean before
washing up in UK's waters (Barry et al. 2023). Even if the identification of
the wood debris washed up after the successive passage of the Ciaran and
Domingos storms (which is the subject of this article) remains speculative,
it seems very likely that this debris originated from the North-West or South-
West Atlantic. The NOAA recently provided a program that allows to track
drifting buoys, using Argos positioning system, developed by Elipot et al.
(2016) (https://www.aoml.noaa.gov/phod/gdp/index.php). Monitoring the
drift of some buoys deployed as part of this program supports our hypothesis
that the wooden debris, considered in this study, presumably have drifted
from the western Atlantic coast.

Barry et al. (2023) developed a model using the daily growth rates of the Capitellum (Evans 1958) and Scutum (Green et al. 1994) of *Lepas anatifera* on a floating object, making it possible to obtain an estimate of the floating time of the debris, as *L. anatifera* can only develop when attached to a single substrate (Barry et al. 2023). The calculation of floating duration (days) is equal to the relation of total length of the barnacle plate (mm) multiplied with the relevant growth rate (mm day⁻¹). Using a typical growth rate of the Capitellum as 0.44 mm day⁻¹ (Evans 1958) and the maximal length of the Capitellum found in our barnacles (i.e. 37 mm), we estimated the maximal floating duration of the wooden debris to be approximately 85 days (almost 3 months). This is consistent with the floating duration for a debris originating from the western Atlantic coast to reach the eastern coast.

On the relation with global change

Since the 1950's, global change has been affecting both terrestrial and
marine biodiversity. It's becoming a well-documented topic in the scientific
community and many predictions are available, depending on the compartment,
research topic or regarding to the IPCC scenario.
Global change can have a number of effects on marine communities, leading to the appearance of NIS. This study shows that extreme events, such as the storms that swept along the European coast in November 2023 resulted in the transportation of *P. marinus*. Although similar extreme events have occurred in recent years, future predictions of the impact of global change on mid-latitude winds and storms can only be speculative, as reliability is low (IPCC 2014). However, it is acceptable that the main cause of transport of this marine debris are currents and winds on the European coast (Van Sebille et al. 2020). Pinto et al. (2009) and Brown et al. (2010) suggest that all the predictable changes could be responsible for an increase in the occurrence of storms and cyclones in the north-east Atlantic (Feser et al. 2015). It is therefore more likely that the synergy or the compounding effect of the change in environmental factors on a global scale, often termed as a global change could correspond to an increase in the occurrence of NIS on European waters.

In this study, we highlight the consequences of an extreme event that resulted in the transport of a non-native species to the European coastline (González-Ortegón et al. 2024). However, this poses no significant risk of invasion under the current conditions, as *Planes* species primarily inhabit floating debris and currently show no tendency to colonize tidal flats (Yaghmour and Al Naqbi 2020). On contrary, it is also an important indication which denotes that global environmental changes can possibly increase the advent of NIS which is conducive to higher number of invasive species. Such circumstances are alarming for the balance of community structure and the symmetry of ecosystem dynamics. Hence, this study tangentially highlights the continual need for monitoring beached floating substances in order to record the NIS, not merely through ballast waters, but also after extreme meteorological events like the Ciaran and Domingos storm in 2023.

## Authors' contribution

Camille Hennion – research conceptualization; sample design and methodology; investigation and data collection; data analysis and interpretation; writing – original draft; writing – review and editing. Jean-Luc Bourgain – investigation and data collection; writing – review and editing. Shagnika Das – sample design and methodology; data analysis and interpretation; writing – original draft; writing – review and editing. Nicolas Spilmont – research conceptualization; sample design and methodology; data analysis and interpretation; writing – review and editing. Emilie Moisez – investigation and data collection. Laurent Seuront – research conceptualization; sample design and methodology; data analysis and interpretation; writing – original draft; writing – review and editing.

## Authors' ORCIDs

Camille Hennion: 00000-0003-2026-9245, Shagnika Das: 0000-0001-6157-6933, Nicolas Spilmont: 0000-0002-2380-1113, Laurent Seuront: 0000-0002-0051-5202.

## Acknowledgements

This work was benefited from the logistic support of the EMIMA platform from the University of Lille. We also acknowledge the anonymous reviewers for the constructive suggestions and the improvement of this manuscript.
## References

Aragaw TA (2021) The macro-debris pollution in the shorelines of Lake Tana: First report on abundance, assessment, constituents, and potential sources. *Science of The Total Environment* 797: 149235, https://doi.org/10.1016/j.scitotenv.2021.149235

Arnaud PM, Bréurols J, Noel P (1972) Portunidae et Grapsidae Des Îles Saint Paul et Amsterdam, Océan Indien (Decapoda, Brachyura). *Beaufortia* 20(259): 7-14

Arnaud F, Arnaud PM, Intes A, Le Loeuff P (1976) Transport d'invertébrés benthiques entre l'Afrique du Sud et Sainte Hélène par les Laminaires (Phaeophyceae). *Bulletin du Muséum National d'Histoire Naturelle 3ème série* 384: 7-14

Barnes DKA (2002) Invasions by Marine Life on Plastic Debris. *Nature* 416: 808–809, https://doi.org/10.1038/416808a

Barry PJ, Beraud C, Wood LE, Tidbury HJ (2023) Modelling of marine debris pathways into UK waters: Example of non-native crustaceans transported across the Atlantic Ocean on floating marine debris. *Marine Pollution Bulletin* 186: 114388, https://doi.org/10.1016/j.marpolbul.2022.114388

Boëtius J (1952) Some Notes on the Relation to the Substratum of *Lepas anatifera* L. and *Lepas fascicularis* E. et S. *Oikos* 4: 112-117, https://doi.org/10.2307/3564807

Bosi S, Broström G, Roquet F (2021) The Role of Stokes Drift in the Dispersal of North Atlantic Surface Marine Debris. *Frontiers in Marine Science* 8: 697430, https://doi.org/10.3389/fmars.2021.697430

Bouvier EL (1940) Décapodes marcheurs. Fédération Française des Sociétés de Sciences naturelles, Vol. 37. Paul Lechevalier et Fils, Paris, 434 pp

Bravo M, Astudillo J, Lancellotti D, Luna-Jorquera G, Valdivia N, Thiel M (2011) Rafting on abiotic substrata: Properties of floating items and their influence on community succession. *Marine Ecology Progress Series* 439: 1-17, https://doi.org/10.3354/meps09344

Brown J, Souza A, Wolf J (2010) Surge modelling in the eastern Irish Sea: Present and future storm impact. *Ocean Dynamics* 60: 227-236, https://doi.org/10.1007/s10236-009-0248-8

Carlton JT, Ruiz GM (2015) Anthropogenic vectors of Marine and Estuarine Invasions: An Overview Framework. In: Canning-Clode J (ed), Biological Invasions in Changing Ecosystems: Vectors, Ecological Impacts, Management and Predictions, De Gruyter Open Poland, pp 24-36

Carlton JT, Chapman JW, Geller JB, Miller JA, Carlton DA, McCuller MI, Treneman NC, Steves BP, Ruiz GM (2017) Tsunami-Driven Rafting: Transoceanic Species Dispersal and Implications for Marine Biogeography. *Science* 357: 1402–1406, https://doi.org/10.1126/science.aao1498

Carranza A, Domingo A, Verdi A, Forselledo R, Estrades A. (2003) First report on the association between *P. cyaneus* (Decapoda: Grapsidae) and loggerhead sea turtle in South Western Atlantic Ocean. *Marine Turtles Newsletter* 102: 5-7

Chace FA Jr. (1951) The oceanic crabs of the genera *Planes* and *Pachygrapsus*. *Proceedings of the United States National Museum* 101: 65-103, https://doi.org/10.5479/si.00963801.101-3272.65

Chace FA Jr. (1966) Decapod Crustaceans from St. Helena Island, South Atlantic. *Proceedings of the United States National Museum* 118: 623-661, https://doi.org/10.5479/si.00963801.118-3536.623

Council of the European Union (2007) Council Regulation (EC) No 708/2007 of 11 June 2007 Concerning Use of Alien and Locally Absent Species in Aquaculture, Vol. 168, 17 pp

Crosnier A (1965) Crustacés Décapodes: Grapsidae et Ocypodidae. Faune de Madagascar 18. Muséum National d'Histoire naturelle, Paris, 143 pp

Crozier WJ (1918) Note on the Coloration of *Planes minutus*. *The American Naturalist* 52: 262-263, https://doi.org/10.1086/279666

Dai A, Yang S (1991) Crabs of the China Seas. China Ocean Press, 720 pp

Das S, Ouddane B, Hwang J-S, Souissi S (2020) Intergenerational effects of resuspended sediment and trace metal mixtures on life cycle traits of a pelagic copepod. *Environmental Pollution* 267: 115460, https://doi.org/10.1016/j.envpol.2020.115460

Das S, Souissi A, Ouddane B, Hwang J-S, Souissi S (2023) Trace metals exposure in three different coastal compartments show specific morphological and reproductive traits across generations in a sentinel copepod. *Science of The Total Environment* 859: 160378, https://doi.org/10.1016/j.scitotenv.2022.160378

Davenport J (1994) A Cleaning Association between the Oceanic Crab *Planes minutus* and the Loggerhead Sea Turtle *Caretta caretta*. *Journal of the Marine Biological Association of the United Kingdom* 74: 735-737, https://doi.org/10.1017/S0025315400047780

Dell RK (1963) *Pachygrapsus marinus* (Rathbun), a New Crab for New Zealand Waters. *Transactions of the Royal Society of New Zealand - Zoology* 3(18): 179-180

Dell RK (1964) The Oceanic Crab, *Pachygrapsus marinus* (Rathbun) in the South-West Pacific. *Crustaceana* 7: 79-80, https://doi.org/10.1163/156854064X00308

Dellinger T, Davenport J, Wirtz P (1997) Comparisons of Social Structure of Columbus Crabs Living on Loggerhead Sea Turtles and Inanimate Flotsam. *Journal of the Marine Biological Association of the United Kingdom* 77: 185-194, https://doi.org/10.1017/S0025315400033865

Dewarumez J-M, Gevaert F, Massé C, Foveau A, Desroy N, Grulois D (2011) Les espèces marines animales et végétales introduites dans le bassin Artois-Picardie. UMR CNRS 8187 LOG et Agence de l’Eau Artois-Picardie, 140 pp

Diagne C, Leroy B, Vaissière A-C, Gozlan RE, Roiz D, Jarić I, Salles JM, Bradshaw CJA, Courchamp F (2021) *High and Rising Economic Costs of Biological Invasions Worldwide*. *Nature* 592: 571–576, https://doi.org/10.1038/s41586-021-03405-6

Díaz M, Gutiérrez J, Jasso D, López C, Sarti L, Vallejo C (1992) Epibiontes y estado físico de las tortugas *Lepidochelys olivacea* y *Dermochelys coriacea* en el Playón de Mexiquillo, Michoacán, durante la temporada de anidación 1988-1989. *Publicaciones de la Sociedad Herpetological Mexicana* 1(1): 19-25
Donelan SC, Miller AW, Muirhead JR, Ruiz GM (2022) Marine Species Introduction via Reproduction and Its Response to Ship Transit Routes. *Frontiers in Ecology and the Environment* 20: 581–588, https://doi.org/10.1002/fee.2551

Edgar GJ (1987) Dispersal of Faunal and Floral Propagules Associated with Drifting *Macrocystis pyrifera* Plants. *Marine Biology* 95: 599–610, https://doi.org/10.1007/BF00393104

Edmondson CH (1959) Hawaiian Grapsidae. *Bishop Museum Occasional Papers* 22(10): 153–202

Elipot S, Lumpkin R, Perez RC, Lilly JM, Early JJ, Sykulski AM (2016) A Global Surface Drifter Data Set at Hourly Resolution. *Journal of Geophysical Research: Oceans* 121: 2937–2966, https://doi.org/10.1002/2016JC011716

Evans F (1958) Growth and Maturity of the Barnacles *Lepas hillii* and *Lepas anatifera*. *Nature* 182: 1245–1246, https://doi.org/10.1038/1821245b0

Feser F, Barcikowska M, Krueger O, Schenk F, Weisse R, Xia L (2015) Storminess over the North Atlantic and Northwestern Europe - A Review. *Quarterly Journal of the Royal Meteorological Society* 141: 350–382, https://doi.org/10.1002/qj.2364

Frick MG, Williams KL, Bolten AB, Bjorndal KA, Martins HR (2004) Diet and Fecundity of Columbus Crabs, *Planes minutus*, Associated with Oceanic-Stage Loggerhead Sea Turtles, *Caretta caretta*, and Inanimate Flotsam. *Journal of Crustacean Biology* 24: 350–355, https://doi.org/10.1651/C-2440

Frick MG, Kopitsky K, Bolten AB, Bjorndal KA, Martins HR (2011) Sympatry in grapsoid crabs (genera *Planes* and *Plagusia*) from olive ridley sea turtles (*Lepidochelys olivacea*), with descriptions of crab diets and masticatory structures. *Marine Biology* 158: 1699–1708, https://doi.org/10.1007/s00227-011-1684-9

Galgani F, Hanke G, Maes T (2015) Global Distribution, Composition and Abundance of Marine Litter. In: Bergmann M, Gutow L, Klages M (eds), Marine Anthropogenic Litter. Springer Cham, pp 29–56, https://doi.org/10.1007/978-3-319-16510-3_2

Geiselman J (1983) The food web of the *Sargassum* community. *Bermuda Biological Station Special Publication* 22: 260–270

González-Ortegón E, Demmer J, Robins P, Jenkins S (2024) Floating plastics as a potential dispersal vector for rafting marine non-native species. *Marine Pollution* 207: 116919, https://doi.org/10.1016/j.marpolbul.2024.116919

Goulletquer P (2016) Guide des organismes exotiques marins. Belin, 304 pp

Goulletquer P, Bachelet G, Sauriau P-G, Noel P (2002) Open Atlantic Coast of Europe - A Century of Introduced Species into French Waters. In: Leppäkoski E, Gollasch S, Olenin S (eds), Invasive Aquatic Species of Europe. Distribution, Impacts and Management. Springer Netherlands, pp 276–290, https://doi.org/10.1007/978-94-015-9956-6_30

Green A, Tyler PA, Angel MV, Gage JD (1994) Gametogenesis in deep- and surface-dwelling oceanic stalked barnacles from the NE Atlantic Ocean. *Journal of Experimental Marine Biology and Ecology* 184: 143–158, https://doi.org/10.1016/0022-0981(94)90001-9

Gündoğdu S, Çevik C, Karaca S (2017) Fouling assemblage of benthic plastic debris collected from Mersin Bay, NE Levantine coast of Turkey. *Marine Pollution Bulletin* 124: 147–154, https://doi.org/10.1016/j.marpolbul.2017.07.023

Gustavson K, Wegeberg S, Geertz-Hansen O, Christensen T (2020) Identification and risk assessment of potential invasive species in Greenland waters. Aarhus University, DCE - Danish Centre for Environment and Energy. Scientific Report No. 391, 38 pp

Hart JFL (1958) A new distributional record for oceanic crabs. Province of British Columbia - Department of Education. Provincial Museum of Natural History and Anthropology. Report for the Year 1958, 31 pp

Hart JFL (1963) Oceanic Crabs Found off the Coast of British Columbia. *The Canadian Field-Naturalist* 77: 127–127, https://doi.org/10.5962/p.342094

Highsmith RC (1985) Floating and algal rafting as potential dispersal mechanisms in brooding invertebrates. *Marine Ecology Progress Series* 25: 169–179, https://doi.org/10.3354/meps025169

Holthuis LB, Sivertsen E (1967) The Crustacea Decapoda, Mysidacea and Cirripedia of the Tristan Da Cunha Archipelago, with a revision of the "frontalis" subgroup of the genus *Jasus*. *Results of the Norwegian Scientific Expedition to Tristan da Cunha 1937-1938* 52: 1–55

Hulme PE (2009) Trade, transport and trouble: managing invasive species pathways in an era of globalization. *Journal of Applied Ecology* 46: 10–18, https://doi.org/10.1111/j.1365-2664.2008.01600.x

IPBES (2019) Global Assessment Report on Biodiversity and Ecosystem Services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. IPBES secretariat, Bonn, Germany, 1148 pp, https://doi.org/10.5281/zenodo.3831673

IPCC (2014) Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Geneva, Switzerland, 151 pp

Jägerbrand AK, Brutemark A, Barthel Svedén J, Gren I-M (2019) A review on the environmental impacts of shipping on aquatic and nearshore ecosystems. *Science of The Total Environment* 695: 133637, https://doi.org/10.1016/j.scitotenv.2019.133637

Jambeck JR, Geyer R, Wilcox C, Siegler TR, Perryman M, Andrady A, Narayan R, Law KL (2015) Marine Pollution. Plastic Waste Inputs from Land into the Ocean. *Science* 347: 768–771, https://doi.org/10.1126/science.1260352

Jara C, Jaramillo E (1979) Hallazgo de *Planes marinus* Rathbun, 1914, sobre boya a la deriva en Bahia de Maiquillahue, Chile. (Crustacea. Decapoda, Grapsidae). *Medio Ambiente (Chile)* 4: 108–113

Jokiel PL (1990) Long-distance dispersal by rafting: reemergence of an old hypothesis. *Endeavour* 14: 66–73, https://doi.org/10.1016/0160-9327(90)90074-2
Kannan G, Mghili B, Di Martino E, Sanchez-Vidal A, Figuerola B (2023) Increasing risk of invasions by organisms on marine debris in the Southeast coast of India. *Marine Pollution Bulletin* 195: 115469, https://doi.org/10.1016/j.marpolbul.2023.115469

Kano Y, Fukumori H, Brenzinger B, Warén A (2013) Driftwood as a vector for the oceanic dispersal of estuarine gastropods (Neritidae) and an evolutionary pathway to the sunken-wood community. *Journal of Molluscan Studies* 79: 378–382, https://doi.org/10.1093/mollus/eyt032

Kepel AA, Spiridonov V, Tsareva L (2002) A Finding of the Crab *Planes marinus* Rathbun, 1914 (Decapoda: Grapsidae) in Peter the Great Bay, Sea of Japan. *Russian Journal of Marine Biology* 28: 206–207, https://doi.org/10.1023/A:1016805622124

Kiessling T, Gutow L, Thiel M (2015) Marine Litter as Habitat and Dispersal Vector. In: Bergmann M, Gutow L, Klages M (eds), Marine Anthropogenic Litter. Springer Cham, pp 141–181, https://doi.org/10.1007/978-3-319-16510-3_6

Lemaitre R (1999) *Planes marinus* Rathbun, 1914. In: Atacama Trench International Expedition (ATIE). Data report. Universita de Genova. Istituto Scienze Ambientali Marine. Facolta di Scienze Matematiche, Fisiche e Naturali. pp 25–30

Mantelatto MC, Póvoa AA, Skinner LF, Araújo FV, Creed JC (2020) Marine Litter and Wood Debris as Habitat and Vector for the Range Expansion of Invasive Corals (*Tubastraea* spp.). *Marine Pollution Bulletin* 160: 111659, https://doi.org/10.1016/j.marpolbul.2020.111659

Massé C, Viard F, Humbert S, Antajan E, Auby I, Bachelet G, Bernard G, Bouchet VMP, Burel T, Dauvin J-C, Delegrange A, Derrien-Courtel S, Droual G, Gouillieux B, Gouletquer P, Guérin L, Janson A-L, Jourde J, Labrune C, Lavesque N, Leclerc J-C, Le Duff M, Le Garrec V, Noël P, Nowaczyk A, Pergent-Martini C, Pezy J-P, Raoux A, Raybaud V, Ruitton S, Sauriau P-G, Spilmont N, Thibault D, Vincent D, Curd A (2023) An Overview of Marine Non-Indigenous Species Found in Three Contrasting Biogeographic Metropolitan French Regions: Insights on Distribution, Origins and Pathways of Introduction. *Diversity* 15: 161, https://doi.org/10.3390/d15020161

Menicagli V, De Battisti D, Balestri E, Federigi I, Maltagliati F, Verani M, Castelli A, Carducci A, Lardicci C (2022) Impact of storms and proximity to entry points on marine litter and wrack accumulation along Mediterranean beaches: Management implications. *Science of the Total Environment* 824: 153914, https://doi.org/10.1016/j.scitotenv.2022.153914

Mghili B, Keznine M, Hasni S, Aksissou M (2023) Abundance, composition and sources of benthic marine litter trawled-up in the fishing grounds on the Moroccan Mediterranean coast. *Regional Studies in Marine Science* 63: 103002, https://doi.org/10.1016/j.rsma.2023.103002

Miranda L, Moreno RA (2002) Epibiontes de *Lepidochelys olivacea* (Eschscholtz, 1829) (Reptilia: Testudinata: Cheloniidae) en la región centro sur de Chile. *Revista de biología marina y oceanografía* 37: 145–146, https://doi.org/10.4067/S0718-19572002000200004

Napper IE, Thompson RC (2020) Plastic Debris in the Marine Environment: History and Future Challenges. *Global Challenges* 4: 1900081, https://doi.org/10.1002/gch2.201900081

Noël P (2002) Les invertébrés aquatiques introduits en France. *Bulletin of the Royal Belgian Institute of Natural Sciences – Biology* 72(Suppl.): 19–27

Pfaller JB, Payton AC, Bjorndal KA, Bolten AB, McDaniel SF (2019) Hitchhiking the high seas: global genomics of rafting crabs. *Ecology and Evolution* 9: 957–974, https://doi.org/10.1002/ece3.4694

Pinto J, Zacharias S, Fink A, Leckebusch GC, Ulbrich U (2009) Factors contributing to the development of extreme North Atlantic cyclones and their relation with the NAO. *Climate Dynamics* 32: 739–739, https://doi.org/10.1007/s00382-008-0525-0

Póvoa AA, Skinner LF, Araújo FV (2021) Fouling Organisms in Marine Litter (Rafting on Abiogenic Substrates): A Global Review of Literature. *Marine Pollution Bulletin* 166: 112189, https://doi.org/10.1016/j.marpolbul.2021.112189

Prado A, de Melo GAS (2002) Le genre *Planes* Bowdich (Decapoda, Grapsidae) sur Les Côtes Brésiliennes (The Genus *Planes* Bowdich (Decapoda, Grapsidae) along the Brazilian Coast). *Crustaceana* 75: 579–595, https://doi.org/10.1163/156854002760095615

Pyšek P, Richardson DM (2010) Invasive Species, Environmental Change and Management, and Health. *Annual Review of Environment and Resources* 35: 25–55, https://doi.org/10.1146/annurev-environ-033009-095548

Questel K (2019) Les crabes et anomoures de Saint-Barthélemy. *Bulletin de l'Agence Territoriale de l'Environnement de Saint-Barthélemy* 5: 34 pp

Rathbun MJ (1914) New genera and species of American brachyrhynchous crabs. *Proceedings of the United States National Museum* 47: 117–129, https://doi.org/10.5479/si.00963801.47-2047.117

Rathbun MJ (1918) The grapsoid crabs of America. *Bulletin of the United States National Museum*. i-xxii, 1-461, https://doi.org/10.5479/si.03629236.97.i

Rech S, Arias RM, Vadell S, Gordon D, Thiel M (2023) Daily Accumulation Rates of Floating Debris and Attached Biota on Continental and Oceanic Island Shores in the SE Pacific: Testing Predictions Based on Global Models. *PeerJ* 11: e15550, https://doi.org/10.7717/peerj.15550

Schneider CA, Rasband WS, Eliceiri KW (2012) NIH Image to ImageJ: 25 years of image analysis. *Nature Methods* 9: 671–675, https://doi.org/10.1038/nmeth.2089

Shimada N (2016) Outline of the Great East Japan Earthquake. In: Urabe J, Nakashizuka T (eds), Ecological Impacts of Tsunamis on Coastal Ecosystems. Lessons from the Great East Japan Earthquake. Springer, pp 1–8, https://doi.org/10.1007/978-4-431-56448-5_1

Spivak ED, Bas CC (1999) First Finding of the Pelagic Crab *Planes marinus* (Decapoda: Grapsidae) in the Southwestern Atlantic. *Journal of Crustacean Biology* 19: 72–76, https://doi.org/10.2307/1549548
Takeda M, Kurata Y (1977) Crabs of the Ogasawara Islands. IV. A collection made at the new volcanic island, Nishino-shima-shinto, in 1975. *Bulletin of the National Science Museum, Tokyo, ser. A (Zoology)* 3(2): 91-111

Tavares M, Mendonça JB Jr. (2022) Brachyuran Crabs (Crustacea, Decapoda) from the Remote Oceanic Archipelago Trindade and Martin Vaz, South Atlantic Ocean. *Zootaxa* 5146: 1–129, https://doi.org/10.11646/zootaxa.5146.1.1

Thiel M, Gutow L (2005) The Ecology of Rafting in the Marine Environment. I. The Floating Substrata. *Oceanography and Marine Biology* 42: 181–264, https://doi.org/10.1201/9780203507810.ch6

UNCTAD (2024) United Nations Conference on Trade and Development (UNCTAD) Handbook of Statistics 2023, 97 pp, https://doi.org/10.18356/9789213585535

Van Sebille E, Aliani S, Law KL, Maximenko N, Alsina JM, Bagaev A, Bergmann M, Chapron B, Chubarenko I, Cózar A, Delandmeter P, Egger M, Fox-Kemper B, Garaba SP, Goddijn-Murphy L, Hardesty BD, Hoffman MJ, Isobe A, Cleo E. Jongedijk CE, Kaandorp MLA, Khatmullina L, Koelmans AA, Kukulka T, Laufkötter C, Lebreton L, Lobelle D, Maes C, Martinez-Vicente V, Maqueda MAM, Poulain-Zarcos M, Rodríguez E, Ryan PG, Shanks AL, Shim WJ, Suaria G, Thiel M, Van den Bremer TS, Wichmann D (2020) The Physical Oceanography of the Transport of Floating Marine Debris. *Environmental Research Letters* 15: 023003, https://doi.org/10.1088/1748-9326/ab6d7d

Ward M (1939) The Brachyura of the Second Templeton Crocker-American Museum Expedition to the Pacific Ocean. American Museum Novitates; No. 1049. The American Museum of Natural History New York City, 15 pp

Wear RG (1970) Life-history studies on New Zealand Brachyura. *New Zealand Journal of Marine and Freshwater Research* 4: 3–35, https://doi.org/10.1080/00288330.1970.9515324

Wicksten MK, Behrens MD (2000) New record of the pelagic crab *Planes cyaneus* in California (Brachyura: Grapsidae). *SCAMIT Newsletter* 19(5): 12

Williams SL, Davidson IC, Pasari JR, Ashton GV, Carlton JT, Crafton RE, Fontana RE, Grosholz ED, Miller AW, Ruiz GM, Zabin CJ (2013) Managing Multiple Vectors for Marine Invasions in an Increasingly Connected World. *BioScience* 63: 952–966, https://doi.org/10.1525/bio.2013.63.12.8

Yaghmour F, Al Naqbi H (2020) First record of Columbus crab *Planes minutus* (Crustacea: Decapoda: Brachyura: Grapsidae) Linnaeus, 1758 for the northwestern Indian Ocean. *Marine Biodiversity Records* 13: 7, https://doi.org/10.1186/s41200-020-00192-3

Zar JH (2010) Biostatistical analysis. 5th edition. Upper Saddle River, Prentice-Hall/Pearson, N.J, xiii, 944 pp

Zettler ML (2021) An example for transatlantic hitchhiking by macrozoobenthic organisms with a research vessel. *Helgoland Marine Research* 75: 4, https://doi.org/10.1186/s10152-021-00549-w

## Web sites, online databases and software

European Environment Agency (2023) Marine Non-Indigenous Species in Europe's Seas. https://www.eea.europa.eu/en/analysis/indicators/marine-non-indigenous-species-in (accessed 13 June 2024)

France Assureurs (2023) Les tempêtes Ciaran et Domingos ont occasionné au total 517 000 sinistres pour un coût de 1,3 milliard d'euros. Communiqué de Presse. https://www.franceassureurs.fr/espace-presse/tempetes-ciaran-domingo-517000-sinistres-cout-de-13-milliard-deuros/ (accessed 11 June 2024)

Gaglioti M, Mazzella V (2021) The itchy issue of Columbus crab *Planes minutus* (Crustacea: Decapoda: Brachyura: Grapsidae) Linnaeus, 1758 on some *C. caretta* specimens off the Pontine Archipelago (Central Tyrrhenian Sea). Short communication. https://doi.org/10.6084/m9.fishshare.15374196 (accessed 11 June 2024)

International Maritime Organization (2004) International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM). https://www.imo.org/en/About/Conventions/Pages/International-Convention-for-the-Control-and-Management-of-Ships%27-Ballast-Water-and-Sediments-(BWM).aspx (accessed 11 June 2024)

NOAA (2024) National Oceanic and Atmospheric Administration. Where does marine debris come from? https://marinedebris.noaa.gov/ (accessed 11 June 2024)

UK Government (2024) Dover Strait Crossings: Channel VTS. https://www.gov.uk/government/publications/dover-strait-crossings-channel-navigation-information-service/dover-strait-crossings-channel-navigation-information-service-cnis (accessed 11 June 2024).

WoRMS Editorial Board (2024) World Register of Marine Species. https://www.marinespecies.org (accessed 11 June 2024)

## Supplementary material

The following supplementary material is available for this article:

**Table S1.** Geo-referenced records of *Planes marinus* previous observations, references and remarks associated.