bluuebunny/crossref_metadata_2025 huggingface dataset:
The Deep‐Water Peyssonnelia Beds from the Balearic Islands (Western Mediterranean)
Authors: Ballesteros Enric
Published: May 2008

Abstract. Peyssonnelia bed distribution on continental shelf bottoms of the Balearic Islands (Western Mediterranean) ranges from 40 to 90 m depth. Different species of Peyssonnelia dominate these bottoms and, according to multivariate techniques, two main assemblages have been distinguished: the Peyssonnelia rosa‐marina beds and the Peyssonnelia sp. beds, together with some transition samples between Peyssonnelia and maërl beds. Erect red algae are always abundant. Although average yearly irradiance reaching these beds is only 6.4‐0.3% of subsurface irradiance, the species richness averages 45 species per sample (1600 cm2) and mean biomass is 2835 g dw. m‐2. The high carbonate content of the living algae of these bottoms suggests that they are important contributors to the production of sediments in the Balearic continental shelf.
Early Growth Stages and Ecology of Arbaciella elegans Mortensen (Echinodermata, Echinoidea) in Southern Spain
Authors: Salas C. , Hergueta E.
Published: May 2008

Abstract. Descriptions of early growth stages of Arbaciella elegans Mortensen, 1910 (Echinodermata, Echinoidea) are given. Three phases of development have been distinguished according to spine morphology and test size: ‘postlarval’, less than 1 mm in size, with a single circle of leaf‐shaped spines; ‘juvenile’, over 1 mm, with new circles of subcylindrical spines added; and ‘adult’, more than 3 mm, with nearly all the spines subcylindrical and several circles of them present.

A recruitment during late autumn and winter is demonstrated. According to sea urchin body size, the rhizomes of Posidonia oceanica and the concretions of Mesophyllum lichenoides provide a good shelter for the postlarvae.
Population Ecology of the Amphipod caprella equilibra Say in a Lagoon Estuary (Northern Adriatic Sea, Italy)
Authors: Sconfietti R. , Lupari P.
Published: May 2008

Abstract. The population ecology and dynamics of Cuprella equilibra were studied in a lagoon estuary of the Northern Adriatic Sea during 1985 to 1986. The breeding activity showed peaks in April and September and a decrease in summer due both to high temperatures and a dystrophic crisis; breeding stops in winter. Females produced more than one brood per year.
Decomposition of Mangrove Wood by Marine Fungi and Teredinids in Belize
Authors: Kohlmeyer J. , Bebout B. , Vlkmann‐Kohlmeyer B.
Published: May 2008

Abstract.Experiments were conducted to determine the decomposition rate of mangrove wood in two areas of differing water nutrient concentrations. Stakes were prepared from prop roots ofRhizophora inangleand from branches ofAvicennia. ConocarpusandLagguncularia. and tied in the natural habitat at two sites—Man‐of‐war Cay (high nutrient concentrations) and Twin Cays (low nutrient concentrations) — off the Belize coast. The stakes were retrieved after 4–24 months and the vertical zonation and succession of higher marine fungi was recorded. Consumption of wood by shipworms (Teredo bartschi), the major decomposers, was measured by digital analysis of the area of wood consumed by these boring organisms.

A total of 20 species of marineAscomycotina, 2Basidiomycotina, and 6 anamorphic fungi were identified from the experimental stakes. Differences in species composition between the two sites of Twin Cays and Man‐of‐war Cay (Belize) were observed, as well as a certain degree of patterning in the vertical distribution of fungi. AmongAscomycotina, members ofHalosphaerialesshow a definite tendency to thrive at greater depths than other species. Mangrove decomposition by shipworms was clearly higher in the nutrient‐rich waters of Man‐of‐war, where the stakes were already heavily riddled after 8 months and had mostly disappeared after 2 years, while they were still intact at the other site. No significant difference in degradation of the 4 species of mangroves was noted.
Vertical Distribution of Meiobenthos in Bathyal Sediments of the Eastern Mediterranean Sea: Relationship with Labile Organic Matter and Bacterial Biomasses
Authors: Danovaro Roberto , Fabiano Mauro , Albertelli Giancarlo , Croce Norberto Della
Published: May 2008

Abstract. Quantitative information on the vertical distribution of meiofaunal abundances and biomass were obtained from samples collected at 3 bathyal stations in the Eastern Mediterranean Sea located at the same depth but characterized by different food supply. Vertical distribution patterns of nieiofauna were investigated in relation to the biochemical composition of the sediment organic matter (proteins, carbohydrates, and lipids) and compared to benthic bacterial standing stocks. No significant relationship between bacteria and meiofauna was found, whereas a significant relationship between protein and lipid concentrations and total meiofauna density was observed. These data suggest that labile organic matter. considered as material readily aVdihbk to benthic consumers, may be an important factor regulating meiofaunal abundance and vertical distribution in deep‐sea sediments.
Tintinnids and Other Microplankton from the Greenland Sea: Abundance and Distribution in the Marginal Ice Zone (MayJune 1989)
Authors: Boltovskoy Demetrio , Vivequin Sandra M. , Swanberg Neil R.
Published: May 2008

Abstract. Microplankton (silicoflagellates, dinoflagellates, tintinnids, pteropods, crustaceans, and fecal pellets) was analysed in 71 0–95 m samples from the Greenland Sea collected from May to June 1989. Abundances were clearly associated with the ice edge, highest concentrations occurring in ice‐free waters. The 15 to 30 m stratum was generally richer in microplankton than deeper waters, with the exception of microcrustaceans, which often peaked below 30 m. Six tintinnid species were identified. The mean size of the tintinnid Parafavella denticulata from the Greenland Sea was consistently greater than that of Barents Sea specimens. It is suggested that colder waters and scarcer food are responsible for these morphometric differences.
Temperature Effects on Photosynthesis and Depth Distribution of the Seagrass Cymodocea nodosa (ucria) Ascherson in a Mediterranean Coastal Lagoon: the Mar Menor (SE Spain)
Authors: Terrados J. , Ros J. D.
Published: May 2008

Abstract. Seasonal variation of temperature effects on photosynthesis and respiration of Cymodorea nodosa (Ucria) Ascherson was investigated in a 1 m depth meadow in the Mar Menor lagoon (SE Spain). Light‐saturated net photosynthesis (Pmax)and dark respiration (R) rates were linearly correlated with water temperature between 10 and 30°C. and 10 and 35°C, respectively, during the year. Water temperature had a similar effect on R rates in August, November, and February, but increased Pmax rates in August vs. those in February, thus promoting a shift of the maximum Pmax/R ratio values from 15°C in February to 30°C in August. P‐I curves had higher Pmax values in May and August than in November or February, while Ic values remained relatively constant throughout the year. Whole‐plant carbon balances suggested that C. nodosa might not be able to survive in the central basin of the lagoon and that the spatial distribution of this seagrass in the Mar Menor might be controlled by light availability.
Abundance and Photosynthetic Characteristics ofTrichodesmiumspp. Along the Atlantic Barrier Reef at Carrie Bow Cay, Belize
Authors: Villareal T. A.
Published: May 2008

Abstract.Trichodesmiumabundance and photosynthetic rates were determined across a transect of the Atlantic Barrier Reef at Carrie Bow Cay, Belize in May 1993 and May‐June 1994. A fore reef station receiving oceanic water had aTrichodesmiumabundance characteristic of the open Caribbean Sea (≤ 102colonies m‐3and 104‐‐105trichomes m‐3). Several species were present; however, in all cases a sharp decrease in abundance occurred across the reef to the coastal lagoon. At this latter site, virtually noTrichodesmiumwas present, although a substantial bloom of the diatomProboscia alataoccurred in 1994.

Maximum photosynthetic rates and the initial light‐limited slopeawere significantly lower in offshore stations than in reef top populations. The increased photosynthetic rates and light‐harvesting ability in reef‐top populations, as well as the lack of significant photoinhibition, indicated that theTrichodesmiumabundance decrease was probably not due to a decline in photosynthetic capacity. Grazing and physical removal rather than a physiological decline were likely mechanisms operating to reduceTrichodesmiumabundance in these regions. These data suggest that the Belizean barrier reef is a sink forTrichodesmiumtransported in from offshore regions.
Benthic Communities of the lnfralittoral in the N. Sporades (Aegean Sea): a Variety of Biotopes Encountered and Analysed
Authors: Simboura N. , Zenetos A. , Thessalou‐Legaki M. , Pancucci M.‐A. , Nicolaidou A.
Published: May 2008

Abstract. The infralittoral benthos was studied on three islands of the Northern Sporades in the Aegean Sea. Thirteen stations were sampled on both hard and soft substrata and 408 taxa were identified, some of zoogeographical interest. Multivariate statistical methods such as classification, ordination and Similarilies Terms Analysis were combined with existing ecological information to delineate the various communities present and to point to the indicator species characterising them. The communities were then defined using the indicator species and their affinities to typical biocoenoses. The main factor responsible for the observed distribution proved to be the type of substratum (algal cover or sediment type), which reflects the light and hydrodynamic conditions. The observed bathynietric zonation was similar lo that of the Balearic Islands in the western Mediterranean.
Growth of Five Species of Gorgonians (Sub‐Class Octocorallia) in the Sedimented Waters of Singapore
Authors: Goh N. K. C. , Chou L. M.
Published: May 2008

Abstract. Annual growth rates of gorgonians in the Indo‐Pacific region are reported ror the first tinie. A method of measuring gorgonian growth using periodic photographic monitoring that is sensitive to horizontal growth and changes in growth foci but that does not require tedious underwater measurements is applied. Growth parameters of five species of gorgonians from three Families (Plexauridae. Melithaeidae. and Subergorgiidae) were monitored over a period of 18 months using this method. Growth rates ranged from 2.30 cm a‐1 to 7.88 cm. a ‐1 in the highly sedimented waters of Singapore. The maximum number of branches added per year ranged from 1.7 to 14.5.
The Effects of Altering Seagrass Canopy Height on Small, Motile Invertebrates of Shallow Mediterranean Embayments
Authors: Connolly R. M. , Butler A. J.
Published: May 2008

Abstract.The height of seagrass canopy was manipulated in experimental plots in meadows of the fine‐leaves seagrassCymodocea nodosaat two sites in the Mediterranean Sea, la Lagune du Brusc, Iles des Embiez near Toulon, and I'Etang de Diana on Corsica. Epifauna (small motile invertebrates associated with the seagrass canopy or sediment surface), was collected at night at both sites, and during the day at Diana only, from three treatments: full seagrass canopy, reduced canopy, and canopy removed entirely. Although epifaunal assemblages from the two sites were different, treatment modification had the same effect at both sites when analysed using multivariate ordinations. Abundance and biomass of total epifauna and of key taxa were all reduced in line with decreasing seagrass cover at both sites at night. The effects of treatment modification on epifauna during the day showed the same trend but were of greater magnitude, both for assemblages and for total abundance and biomass. At both sites and at both times, the fauna of plots from which seagrass had been cut tended to be dominated by animals of higher biomass than the fauna of plots with full canopy. Epifauna form the major dietary component of small fish inhabiting shallow, sheltered embayments. These results are therefore consistent with a model in which reduced abundance of fish associated with reduced seagrass canopy is explained by a reduction in food availability.
Observations on the Burrows and Burrowing Behaviour of the Red Band‐Fish, Cepola rubescens L.
Authors: Atkinson R. James A. , Pullin Roger S. V.
Published: May 2008

Abstract. The red band‐fish, Cepola rubescens L., lives in burrows in sublittoral muddy sediments. The authors first presented information on the burrows of this species in the 1970s. The present paper presents new information on burrow structure, describes the method of excavation, and comments on the bioturbatory significance of the species. The work derives from field and laboratory studies. A burrow typically consists of a vertical shaft which opens into an expanded terminal chamber. In some cases a side shaft may be added. The paper includes a size analysis of 130 burrows measured in the field and detailed morphological information from a selection of burrows which were cast with polyester resin. The fish burrows are frequently intersected by the burrows of other species and interspecific associations may develop. Burrow size reflects the size of the occupant and may approach 1 m in depth. The biogenic movement of water and particles to this depth is often overlooked in bioturbation studies and is discussed. Burrow distribution is aggregate, which has implications for the bioturbatory impact of the species. Burrows are constructed by mouth excavation and this is described in detail. Fish transport fine material within their mouths and coarse material is grasped in the jaws. Large spoil heaps occur at burrow openings. One obvious effect of this bioturbatory activity at the field site was the redistribution of coarse material (shell gravel) from depth to the sediment surface.
Ficopomatus‘Reefs' in the Po River Delta (Northern Adriatic): Their Constructional Dynamics, Biology, and Influences on the Brackish‐water Biota
Authors: Bianchi Carlo Nike , Morri Carla
Published: May 2008

Abstract. The serpulid polychaete Ficopomatus enigmaticus (Fauvel, 1923) builds huge aggregates in the “Sacca del Canarin”, a brackish inlet of the Po River Delta (Italy). Distribution, structure and development of these ‘reefs’. together with their associated biota, were studied by field observations and settlement panels from 1977 to 1979. Some aspects of the serpulid biology (settlement periods, tube growth, life strategy) were also taken into account. Ficopomatus reefs influence in many ways the brackish‐water ecosystem: they form the main hard substrate; are major sediment source; help in regulating the trophic status of the lagoon; and act as refuge for many invertebrate species.
Cephalopods Burying in Soft Substrata: Agents of Bioturbation?
Authors: Boletzky Sigurd von
Published: May 2008

Abstract. Among the bottom‐living cephalopods, those able to dig into soft substrata show special behaviour patterns involving coordinated mantle/funnel, fin, and arm movements. This activity is triggered by light, and in the euphotic zone thus occurs at least once in a 24 h cycle. Effects of burial on the sediments are considered, drawing attention to the likely chemical side effects, especially relating to the mucus released by burying cephalopods. Persistent burrows are produced only by some octopuses. Their burial activities and the sand/mud digging of many squids and cuttlefishes are likely to play a notable role in bioturbation.
Microzooplankton Grazing in the Southern Ocean: Implications for the Carbon Cycle
Authors: Froneman Pierre , Perissinotto Renzo
Published: May 2008

Abstract. Microzooplankton grazing and protozooplankton community structure was investigated in austral summer (Jan./Feb.) and winter (June/July) 1993 in the Atlantic sector of the Southern Ocean during the SAAMES (South African Antarctic Marine Ecosystem Study) Il and III cruises. Grazing was estimated at 22 stations in summer and at 15 stations in winter by employing the sequential dilution technique. Nano‐heterotrophic flagellates (< 20 μm) and ciliates (aloricate ciliates and tintinnids) dominated the protozooplankton assemblages along both transects. Densities in winter were, however, nearly an order of magnitude lower than in summer. Microzooplankton grazing removed between 0 and 28% (mean = 13.2%) of the initial phytoplankton stock in summer and, between 24 and 51 % of the initial stock (mean = 37.6%) in winter. The potential primary production removed during summer ranged between 0 and 46% (mean = 22.0%) compared with the winter range of 56–83% (mean = 67.2%). Size selectivity grazing experiments conducted during both studies suggest that microzooplankton preferentially graze on the nano‐ (20–2.0μm) and picophytoplankton (2.0–0.2μm) size fractions. These results have important implications for the efficiency of the carbon pump in the Southern Ocean. During summer when the larger cells dominate phytoplankton biomass, the bulk of the photosynthetically fixed carbon appears to be channelled to the meso‐ and macrozooplankton fractions. This results in a rapid transfer of organic carbon out of the zone of regeneration to the deep ocean via vertical migration and large faecal pellet production. During winter, however, an increase in the contribution of the smaller size fractions to total phytoplankton biomass results in a greater proportion of the photosynthetically fixed carbon being channelled to the microzooplankton fraction. The efficiency of the carbon pump is, therefore, reduced in that the transfer of carbon below the zone of regeneration is reduced as carbon is recycled mostly within the microbial loop in the upper mixed layer.
Development of Small Mytllus Beds and its Effects on Resident Intertidal Macro fauna
Authors: Günther Carmen‐Pia
Published: May 2008

Abstract. The development of temporary Mytilus edulis beds and their associated macro fauna was studied on an intertidal sand flat in the German Wadden sea during 1986 by comparing mussel beds with bare sandy areas of the same tidal elevation. Macro fauna samples We taken with a 100 cm2 corer (penetration depth 27 cm, mesh size 0.5 mm, 5 parallel samples).

Numbers of taxa and diversity were higher in the mussel beds compared to the sandy areas. The abundance of macro fauna organisms decreased with the age of the mussel bed, whereas the relative abundance of species was not strongly affected. Hydrobia ulvae, oligochaetes, and Heteromastus filiformis dominated the macro fauna inside as well as outside the mussel beds. Among the lower ranks of dominance changes in species composition were observed due to increasing densities of opportunistic polychaetes.

About six weeks after the establishment of the mussel beds a higher abundance of Capitella spp., Polydora ligni, Tharyx marioni, and nemerteans occurred within the mussel beds while other species such as Hydrobia ulvae and Pygospio elegans showed a significantly lower abundance compared to the adjacent flat. Macoma balthica as well as Mya arenaria were not affected by the alteration of a bare sand flat to a mussel bed. O‐group Carcinus maenas reached their highest abundance in the mussel beds (over 1000 indiv. m‐2). In contrast juvenile Crangon crangon preferred the bare sand flat. After destruction of the mussel beds by an early autumn storm, species abundance and composition was similar to the situation before the mussel beds had become established.
Impact of Biodeposition on Macrofaunal Communities in Intertidal Sandflats
Authors: Kröncke Ingrid
Published: May 2008

Abstract. This investigation deals with the changes in macrofaunal communities in intertidal sandflats caused by the input of organic material via biodeposition produced by mussel beds. The area of investigation was the back barrier tidal flat system behind the East Frisian Island of Spiekeroog. Due to erosion by the ebb current a plume of biodeposits extended from an area of mussel beds (Mytilus edulis) towards the adjacent sandy sediments. This plume represented a gradient of decreasing contents of organic material. Five stations were installed along this gradient to analyse the effects of this organic input on the macrofaunal communities; a control station was placed on sandy sediments.

The macrofaunal communities differed along the transect. In the mussel patches oligochaetes dominated, whereas deposit‐feeding polychaetes increased along the transect. These polychaetes were different from the communities of the sand flats. The changes in the macrofaunal communities discussed in the framework of the organic carbon contents of sediments and interspecific relationships.

After a cover of green algae during summer and after a cold winter, the mussels were almost completely eliminated from the area of investigation and reaggregated in another area of the flat. The layer of biodeposits eroded as well. After the decrease in contents of organic matter, the macrofaunal communities no longer followed the transitional distribution but showed a diffuse and seasonally influenced distribution.

The results indicate that biodeposits changed the quality of the sediment structure of the sand flats and that the amount of organic matter (TOC) is a main structuring factor for the macrofaunal communities.
The Boreholes of the Sea Urchin Genus Echinometra (Echinodermata: Echinoidea: Echinometridae) as a Microhabitat in Tropical South America*
Authors: Schoppe Sabine , Werding Bernd
Published: May 2008

Abstract. Members of the genus Echinometru (Echinoideu: Echinometridue) inhabit hard substrata in shallow waters where they live in self‐excavated dwellings. Boring by Echinometru spp. causes a secondary structure of the surface, thus forming additional microhabitats.

In this study the effects of boring activities of Echinometru lucunter (L.) along the Caribbean coast of Colombia and of Echinometra vunbrunri A. Agassu in the Colombian Pacific is examined. Several species inhabit the boreholes occupied by these urchins. The associates live underneath the echinoid on the bottom of the borehole, where they find shelter from exposure and predators. The co‐inhabitants of E. lucunter include the porcellanid Clusroroechus vunderhorsri (Schmitt), the recently described brit‐tlestar Ophiorhrix synoecim (Schoppe), and the clingfish Acyrrus rubiginosus (Poey). The species co‐occumng with E. vunbrunti include the porcellanid crab Clusroroechus gorgonensis Werdingamp; Haig and the clingfish Arcos decoris Briggs. With the exception of A. decoris, all of these species are obligatorily associated with the Echinomerra host.
Water Quality Improvements in Liverpool Docks: The Role of Filter Feeders in Algal and Nutrient Dynamics
Authors: Wilkinson Stephen B. , Zheng Weizhong , Allen Janette R. , Fielding Nicola J. , Wanstall Vanessa C. , Russell George , Hawkins Stephen J.
Published: May 2008

Abstract. The redevelopment of disused docks around Liverpool into areas suitable for shops, offices, housing and recreational watersports has necessitated the maintenance of good water quality in these areas. The main source of water to the docks is the River Mersey, which contains high concentrations of nutrients, encouraging algal blooms ‐ including potentially nuisance species ‐ in the enclosed dock basins. Since 1988 an extensive monitoring programme has been run sampling the hydrography, plankton and benthos of the docks. During this period there has been an improvement in water quality, including a reduction in summer phytoplankton biomass and anoxic bottom water. There are strong indications that phytoplankton biomass has been severely reduced by the filter feeding of Mytifus edulis. Changes in the composition of the benthic community since 1988 suggest that the large population of M. edulis is now suffering from limited recruitment. The long‐term development and stability of the system is discussed with reference to community succession and its link to ecosystem functioning.
Analyses of the Relationship Between Mucous Aggregates and Phytoplankton Communities in the Gulf of Trieste (Northern Adriatic Sea) by Multivariate Techniques
Authors: Cataletto Bruno , Feoli Enrico , Umani Serena Fonda , Monti Marina , Pecchiar Irene
Published: May 2008

Abstract. Multivariate techniques (cluster analysis and Principal Component Analysis) applied on phytoplankton data collected in June, July, August, and September 1990, 1991, 1992, and 1993 in the Gulf of Trieste (Northern Adriatic Sea) highlighted a clear temporal pattern from 1990 to 1993. In the summer of 1991, phytoplankton communities showed a dramatic increase in the dinoflagellatddiatom ratio. In particular, during June and July 1991 only few specimens of diatoms (Cylindrorhecu closreriurn. Probosciu alata, Nirzschio longissimu, and Nitzschiu spp.) were collected; this confirmed the diatom scarcity in the phytoplankton communities before and during the appearance of large mucous aggregates (mucilage) in July 1991 in the Gulf of Trieste. The differences observed between the structure of the phytoplankton communities inside the aggregates and in the ambient waters suggested two hypotheses: 1) the aggregates were not produced in the gulf, but were carried ints the gulf by the eastern bordering current; 2) the aggregates were produced by a few, scarce species with a high exudate production that are capable of quickly reaching a high reproductive rate within the aggregates.
Effects of a Short‐term Environmental Change on a Brackish‐water Polychaete Community
Authors: GIANGRANDE ADRIANA , FRASCHETTI SIMONEITA
Published: May 2008

Abstract. Aquatina lake is a brackish basin, connected with the Adriatic Sea along the mast of Apulia (Italy), with a mean salinity of 26%. The abundance and biomass of fifteen polychaete species were recorded by monthly samples in a pilot area of the lake from February 1989 to February 1990. Naineris laevigata was dominant, both in number of individuals and biomass. During 1990, obstruction of freshwater inflow to the lake caused an increase in salinity up to 4O%, followed by some changes in the polychaete community. Noromasrus hiericeus became dominant, and the abundances of the other species decreased except for Naineris laevipru. Salinity assumed normal values after three months, but community responded slowly becauie the massive presence of N. latericeus inhibited the recovery of other species. An abiotic disturbance, followed by a biotic disturbance, altered the structure of the polychaete community.
Effects of Dredging Activities on Growth of Laminaria saccharina
Authors: Lyngby Jens Erik , Mortensen Sverre Mohr
Published: May 2008

Abstract. The possible effects of fine‐grained deposits on the photosynthesis, growth, and nutrient uptake of Laminaria have been studied in field and laboratory experiments. Some of the plants were treated with fine‐grained material for two hours and then transplanted in rows together with untreated plants. At two‐week intervals the treatment was repeated and samples collected. The macroalgae were analyzed for growth as well as chlorophyll a, nitrogen, and phosphorus content. In the laboratory experiments, plants of a uniform size were incubated in Plexiglas containers after leaf‐marking and treatment in a sediment suspension. At weekly intervals, photosynthesis, growth, chlorophyll a, and nutrients were analyzed.

The field study showed that Laminaria growth was significantly affected by the fine‐grained material. The growth in the control experiment was 20% higher than in the treated plants. The chlorophyll a concentrations in the treated plants were significantly lower than in the control experiment, and the results indicated a reduced nutrient uptake in the treated plants. In the laboratory experiments the growth of the treated plants was only 30% of the controls, but no differences in photosynthetic capacities were detected. Nitrogen uptake was reduced in the treated plants, but no effects were observed on phosphorus uptake. Thick layers of fine‐grained material caused direct harmful effects and rotting.

The results are discussed in relation to dredging activities; it is concluded that in heavy sedimentation areas, Laminaria growth may be significantly reduced beyond the indirect effect of shading from suspended material in the water.
How Episodic Coral Breakage Can Determine Community Structure: A South African Coral Reef Example
Authors: Riegl Bernhard , Riegl Andrea
Published: May 2008

Abstract. Africa's southernmost coral reefs are situated in Natal Province, South Africa. The Natal coast is exposed to open Ocean swells and episodic storm swell conditions. Benthic communities on these reefs differentiated into three community types: shallow reefs (8–18 m) were dominated by alcyonacean corals and low‐growing, massive Scleractinia; intermediate reefs (18–25 m) were dominated chiefly by branching and tabular Scleractinia of the genus Acropora (A. austera, A. clathrata); deep reefs were not dominated by corals but by sponges. Breakage and recovery experiments indicated that the difference in Acropora dominance between shallow and intermediate sites was caused by breakage in high swell conditions. Survival of experimentally produced A. austera fragments was significantly higher in intermediate than in shallow sites, where higher surge made re‐attachment and regeneration unlikely. Also, colony morphology was adapted to differential surge conditions: colonies on the shallow reefs were smaller with shorter branches, while on intermediate reefs they were much bigger with long, widely spreading branches. Episodic breakage and low fragment survival due to high water‐motion thus excluded branching corals from shallow reef sites.
Impact of Two “El Niño” Events of Different Intensity on the Hypoxic Soft Bottom Macrobenthos off the Central Peruvian wast
Authors: Tarazona Juan , Arntz Wolf E. , Canahuire Elba
Published: May 2008

Abstract. Monthly changes in the community structure of hypoxic soft‐bottom macrobenthos have been studied at a station at 34 m depth in Ancón Bay (Peru) before and during two El Niño (EN) events. Of these events, 1982‐83 is considered the strongest, and 1991–93 one of the most prolonged in the 20th century. On the oceanographic scale, EN 1982–83 ranges as “very strong”, whereas EN 1991–93 ranges as “moderate”.

The thermal anomalies at the station during EN 1982–83 (+ 7.8 °C) were almost twice those of EN 1991–93 (+ 4.1 °C). However, the community changes were not in all cases proportional to the extent of warming. Species numbers increased in a similar way (up to 24 species from near zero in each of the two events), but maximum faunal density was five times higher, and mean biomass was twice as high in 1982–83 compared with the event a decade later. Species diversity was slightly higher during EN 1982–83, whereas successional and trophic changes occurred on a broader scale during EN 1991–93. On the whole, the impact of the long‐lasting event on the small soft‐bottom macrofauna was not much weaker than that of the exceptionally strong event.

The authors discuss the mechanisms which may be responsible for the differences and similarities encountered in the benthic community dynamics during these two events. Both in the unusually strong and the unusually long EN, the community revealed a pattern of early biological response several months ahead of the onset of local warming which marks the official begin of EN. The question is addressed to what extent the increase of certain parameters in the benthic community could be used for predictive purposes.
The Influence of Mucous Aggregates on the Microphytobenthic Community in the Northern Adriatic Sea
Authors: Welker Chiara , Nichetto Paola
Published: May 2008

Abstract. An extended reappearance of mumus aggregates in the Northern Adriatic Sea in 1991 gave rise to the hypothesis of a possible influence of the mucus, settled on the bottom, on benthic flora and fauna.

This work investigates the variations in the microphytobenthic community in three stations of the Gulf of Trieste (AA1, AA2, AA3) during 1991, when mucous aggregates were present, and during the two following years, when no such aggregates were observed.

Water samples were collected by Niskin bottle in the bottom layer for nutrient analysis, and sediment samples were collected by divers. The diatom species and cell densities were determined under an inverted microscope. All the data were processed with the aim to evaluate community composition and possible relations with the presence of mucous aggregates in 1991.

The results showed a general decrease of benthic diatoms from 1991 to 1993, both in quality and quantity, for all the investigated sites. Statistical analyses on microphytobenthos, hydrological parameters, and nutrient concentrations indicated differences among the considered years. The microphytobenthic community in summer 1991 appeared to be quite different from those of the other years. The density of benthic diatoms was apparently not correlated with nutrient availability in the bottom layer, but was rather influenced by changes in temperature.

The presence of a dense microphytobenthic community in 1991 might be explained by a combination of adequate conditions related to the presence of mucous aggregates, including a more undisturbed substratum caused by the interruption of dredging, decreased grazing pressure due to a declined filtering capacity of epifauna, and nutrient‐rich sediment for extra nutrient disposal remineralized at the mucus‐sediment interface. The mucilage aggregates therefore apparently stimulated the microphytobenthic community, in contrast to the effects on the benthic macrofauna, which were perturbed by the mucus.
A Scenario of the Late‐Pleistocene‐Holocene Changes in the Distributional Range of Antarctic Krill (Euphausia superba)
Authors: Spiridonov Vassly A.
Published: May 2008

Abstract. Oceanographic evidence along with the data on Euphausia superba distribution indicate that the reproductive range of this species is related to the southernmost core of the Antarctic Circumpolar Current (ACC), the Weddell Gyre, the Ross Gyre, and the systems of mesoscale eddies in the Bellingshausen Sea, in the Prydz Bay area. and the D'Urville Sea. During the Last Glaciation Maximum, at ca. 18 ka BP, both the Weddell and the Ross Gyres as well as near‐coastal circulations probably lost their importance in the maintenance of Antarctic krill populations due to cooling of the water column and development of multi‐year sea ice. Within the ACC at that time, some smaller‐scale circulations related to islands and seamounts could have played a major role in controlling krill distribution. If, nevertheless. refugia for self‐maintained krill populations remained in the near‐coastal zone, particularly in the eastern Indian sector, geographical isolation might have caused divergence between the two species of the gregarine Cephaloidophora commonly infesting krill at present.
Short‐Term and Small‐Scale Variation in Food Availability to Natural Oyster Populations: Food, Flow and Flux
Authors: Wilson‐Ormond E. A. , Powell E. N. , Ray S. M.
Published: May 2008

Abstract.Food resources and water flow speeds vary on short‐temporal and small‐spatial scales important to feeding in natural populations of oysters (Crassostrea virginica). To better describe food availability to the oyster population, micro‐current meters were used to measure flow 1–3 cm above the bottom and frequent water sampling was used to determine the quantity and composition of the seston on Confederate Reef, Galveston Bay, Texas. The quantity and quality of food varied on time scales at least as short as 3 h and throughout the water column. Seston was high in detrital carbon, nitrogen poor, and had a high fraction of inorganic particles. The quantity of food at the bed was not predictable from samples taken near the surface. Water flow speeds were also highly variable. Whereas rapid flow speeds were measured, flow speed tended to cluster about a narrower range of slower speeds resulting in the mean speed being much higher than the median. Fluxes of food calculated from the quantity of food and water flow speeds were low and highly variable. Under most conditions, water flow speed was more important than food quantity in determining flux. Rapid flow rates could overcome low food quantity to result in relatively high fluxes, whereas slow flow resulted in small fluxes even if food was abundant. Changes in water flow rate associated with tidal changes and changes in speed are probably the primary agents controlling food availability on a daily basis. Decreased wind speed at night normally reduced flux in the early morning hours, for example. These results stress the importance of measuring food quantity and water flow speed on spatial and temporal scales important to oyster feeding. Model simulations of oyster populations at varying densities, flow rates and clump heights across the range of measured values show that flow rate is insufficient during most hours of the day and days of the year to prevent oysters from locally reducing food supply by their filtering efforts. Thus flow rate probably limits population density and adult size on Confederate Reef.
Life in the Slow Lane: Growth and Longevity of Cold‐seep Vestimentiferans
Authors: Fisher C. R. , Urcuyo I. A. , Simpkins M. A. , NIx E.
Published: May 2008

Abstract.Yearly,in situgrowth of two species of cold‐seep vestimentiferan tubeworms was measured using a combination of banding and video analysis. A total of 53 animals from 15 different aggregations were included in the study, which was conducted over a Cyear period. The most common species,Lamellibrachiasp., grows very slowly (averaging 0.77 cm. a‐1) and yet commonly reaches lengths over 2 m. Based on conservative calculations we conclude that individuals in mature aggregations are a minimum of 100 a old and are likely to be much older. Smaller numbers of a second species of vestimentiferan (related to escarpids) were also monitored over this period. We consider it likely that the individuals of the second species banded for this study were already on the plateau of their growth curve, and that the very low average growth rates recorded here would lead to an overestimate of the ages of the individuals used in this study. However, life history considerations combined with the extremely low measured growth rates of this species suggest it is also long‐lived.
The Amphipod Community as a Bioindicator in Algeciras Bay (Southern Iberian Peninsula) Based on a Spatio‐Temporal Distribution
Authors: Conradi M. , López‐González P. J. , García‐Gómez C.
Published: May 2008

Abstract. The amphipod population associated with Bugula neritina (L.), a verycommon bryozoan species in Algeciras Bay (Strait of Gibraltar), was studied on a spatio‐temporal scale, in order to define its role as a bioindicator. Samples were collected in December, March, June and September along a transect running from the external to the internal sampling stations.

Fifty‐three species belonging to 22 families were identified; the most abundant species were Jassa marmorata Holmes, Ischyrocerus inexpectatus (Ruffo) and Phtisica marina Slabber.

The spatial evolution of the amphipod community reflected the physico‐chemical conditions of Algeciras Bay, yielding a clear gradient from the outer to the inner stations. The stations located at the mouth of the bay, characterised by high hydrodynamism and low sedimentation, had a higher diversity and species richness than the inner stations with low water movement and higher sedimentation. Eight species preferred for the outer stations, while another nine species were typical of the inner harbours.

The most notable aspect of the seasonal evolution was the increased dominance of the tube‐builder and deposit‐suspension feeder Jassa marmorota.

Structural and ordination analyses corroborate the outer‐inner gradient in the bay and illustrate the importance of hydrodynamic forces and sedimentation in the amphipod community.
Nereis diversicolor: an Unreliable Biomonitor of Metal Contamination in the ‘Ría de Bilbao’ (Spain)
Authors: Saiz‐Salinas J. I. , Francés‐Zubillaga G.
Published: May 2008

Abstract. Samples of the polychaete Nereis diversicolor O.F. Müller and surficial sediments from a clean and a polluted estuary were taken during a year at monthly intervals to determine, by comparison, the range of temporal fluctuations in trace metal concentrations. Whereas metal variations in surficial sediments were more pronounced in the polluted estuary, concentrations in N. diversicolor in both estuaries showed a wide range of temporal variation that surpassed that of surficial sediments. A clear decline in all metals studied (except Mn) from polluted sediments was noted after episodes of strong rainfall. In the reference estuary the fluctuations were less pronounced. Metal body burdens in N. diversicolor from the two estuaries were usually quite similar even though total levels in sediments differed considerably, indicating a lack of worm‐sediment relationship. The low level of Cu, Cr and Pb in the tissues of N. diversicolor suggest a mechanism which prevents the polychaete from being exposed to these metals in highly polluted sediments. Therefore, it is concluded that N. diversicolor cannot be considered to be an ideal biomonitor of metal contamination in the polluted Bilbao Estuary.
Oxygen Uptake During Repeated Exposure to Temperature Change: Physiological Divergence in Panamanian Cognate Pairs and Latitudinally Distant Populations of Decapod Crustacea
Authors: Ferraris J. D. , Norenburg J. L.
Published: May 2008

Abstract.The emergence of the Isthmus of Panama subdivided the amphi‐American biota. In the present study, Pacific and Atlantic populations of four cognate pairs of crabs were used to discern whether exposure to different thermal regimes in habitats, in the putative absence of gene flow, has resulted in physiological divergence. Populations that potentially form a common genetic pool were also used; these were populations of the Atlantic Panama cognate that occur in Belize and Florida. Decreases in water temperature occur periodically in Pacific Panama and Florida, but not in Atlantic Panama or Belize. In this study, physiological divergence in oxygen uptake was assessed in response to repeated exposure to either control and decreased temperature or control and increased temperature. Results indicate that, in only some of the genera tested, exposure to decreases in habitat temperature has resulted in divergence. Partial support is found for the corollary that adaptation to an environment with periods of decreased temperature results in reduced compensation during exposure to elevated temperature.
Nitrogen Assimilation and Partitioning in the Mediterranean Seagrass Posidonia oceanica
Authors: Kraemer G. P. , Mazzella L. , Alberte R. S.
Published: May 2008

Abstract. The supply of nitrogen (N) often limits the productivity of marine macrophytes. In vitro and in vivo assays of glutamine synthetase (GS) activity were employed to investigate patterns of N assimilation by the Mediterranean seagrass Posidonia oceanica (L.) DELILE. Biomass‐specific GS activity wa measured in root tissue, in leaves within a shoot, in shoots collected at two sites during two season and over a depth range of 5–33 m. Root tissue was less important than shoot tissue in assimilating inorganic N in P. oceanica, due both to the small roots' biomass (ca. 3% of total plant biomass and greatly lower (10‐ to 50‐fold) GS activities. While the GS activity and N assimilatory potentia (biomass × GS activity; μmol N‐h‐‐1) were greatest in leaf 2, leaves 1 and 3–5 assimilated N a significant rates. Shoots from a site characterized by elevated N availability in the winter water column and no significant sediment N reservoir exhibited GS activities that were 9‐times higher than shoot from a more oligotrophic site. Shoot GS activities in July increased linearly from 5 to 33 m and wer correlated with light availability as defined by Hsat, (daily period during which photosynthetic reaction are light‐saturated). This may represent metabolic compensation by P. oceanica to maintain N influx. Factors contributing to the ecological success of P. oceanica include the ability to assimilate N under conditions of severe light limitation (< 35 μmol photons. m‐2. s‐1), and metabolic plasticity to ensur the de novo generation of N‐containing organic compounds.
Morphology, Distribution, Life Habits and Phylogenetic Affinities of the Recent Brachiopod Gwynia capsula (Jeffreys)
Authors: Logan A. , MacKinnon D. I. , Phorson J. E.
Published: May 2008

Abstract. For more than a century, the Recent micromorphic trocholophous brachiopod Gwynia capsula (Jeffreys) has remained inadequately understood. In this paper we provide new information on its life habits and geographic distribution and present a revised morphological description which corrects inaccuracies in various descriptions of the species. We also note the suppression of punctation in four specimens of G. capsula in an otherwise morphologically normal population from Connemara. Eire. We reject past suggestions by some authors that Gwynia may represent the juvenile stage of some other brachiopod. G. capsula is compared to the diminutive Recent brachiopod Argyrotheca cistellala (Searles‐Wood). with which it often occurs, and also with the Middle Jurassic micromorph Zellania davidsoni Moore. On the basis of a morphological comparison between Gwynia and Zellania, a case is made for considering Gwynia as a paedomorphic descendant of Zellania, notwithstanding the considerable time gap separating the two forms. Their systematic positions with respect to other tere‐bratulide genera have, however, yet to be resolved.
Response of Summer Phytoplankton to Episodic Meteorological Events (Gulf of Trieste, Adriatic Sea)
Authors: Malej A. , MozetiČ P. , MalaČČ V. , Turk V.
Published: May 2008

Abstract. Despite increasing evidence that atmospheric deposition may contribute considerably to new production in coastal seas, the role of this nutrient source in the shallow northern Adriatic ecosystem has remained largely unassessed. This study demonstrates that locally collected rain water significantly stimulates primary production and phytoplankton biomass accumulation in microcosm experiments. The concentration of nutrients in rain water collected during summer storms (11.38–77.19 μmol·1‐1 nitrate. 4.45–36.38 μmol.1·1 ammonium, 0.93–4.75 μmol·1‐1 phosphate) indicated that the precipitation is influenced by anthropogenic emissions from urbanised and industrialised regions of the European continent. Rainfall events delivered relatively large (127 tons nitrogen, 9.5 tons phosphorus in the period 10 June to 10 September, 1993). though episodic, nutrient input into the area. Field measurements showed that storm events were followed by an increase of phytoplankton standing crop and a shift of community structure.
Feeding of the Sparid Fish Sarpa salpa in a Seagrass Ecosystem: Diet and Carbon Flux
Authors: Havelange S. , Lepoint G. , Dauby P. , Bouquegneau J.‐M.
Published: May 2008

Abstract. In Revellata Bay Gulf of Calvi, Corsica, France, the sparid fish Sarpa salpa L. is the main macro‐consumer of Posidonia oceanica L. Delile leaf. Stomach contents were analysed and 13C/12C isotopic ratios were measured in fish muscle and potential food sources algae, P. oceanica leaf and its epiphytes to determine their relative contribution to the fish diet. S. salpa has an age‐related mixed diet: juveniles are plankton feeders, young, sub‐adults and adults are herbivorous, and, the older the individuals, the higher the relative contribution of P. oceanica to the diet. Our results and former studies of carbon stocks and fluxes in the P. oceanica bed of Revellata Bay have enabled an estimation of the general impact of S. salpa grazing on infralittoral communities: the studied species consumes 24 g C.m‐2 ‐a‐1 from P. oceanica leaf, 4.8 from epiphytes and 13 from epilithic algae. The fish net production and biomass turnover in that zone have been estimated to be 1.2gC.m‐2.a‐1 and 1.5 a‐1, respectively.