A multi-technique approach was used to map the spatial distribution of seabed biotopes (i.e. physical habitats and their associated benthic assemblages) in the vicinity of Hastings Shingle Bank in the eastern English Channel, part of which is licensed for the extraction of marine aggregates for the construction industry. An area of seabed, approximately 12×4 km in size, was surveyed using a high-resolution sidescan sonar system, and a mosaic of the output was produced, covering 100% of the survey area. The area was then divided into acoustically distinct regions based on the sidescan sonar data, and the benthic communities and sediment types within each of the regions were ground-truthed using a Hamon grab fitted with a video camera, and using a heavy duty 2-m beam trawl. Additional information concerning the seabed was obtained through the application of video and photographic techniques. Sediments within the survey area ranged from cobbles and coarse gravels on the Shingle Bank, to various grades of sands to the north and south. Analysis of faunal data revealed the presence of statistically distinct biological assemblages within each acoustic region. Using all available data, four discrete biotopes were identified and their spatial distribution mapped across the survey area.

Spatial surveys of marine benthic habitats and biota based on the interpretation of acoustic data were carried out at two sites in the eastern English Channel each representing different scales of geographic area and intensity of survey. A small area (4×12 km) crossing the Hastings Shingle Bank was surveyed at a relatively high intensity (track spacing 400 m) and was nested within a larger area between Hastings and Dungeness (12×40 km), which was surveyed at a lower intensity (track spacing 2 km). Surveys were conducted with two acoustic ground discrimination systems (AGDS), RoxAnn and QTC-VIEW and the primary purpose of the investigation was to compare the performance of the two AGDS using a common approach to analysis of the different data outputs (E1 and E2 for RoxAnn and the Q eigenvectors from QTC-VIEW). Exploratory data analysis using variography indicated that interpolation between tracks was justified for the smaller site to create a complete coverage, but was limited to the creation of a digital image of the track data for the larger area. Grab and video sample data were available for supervised classification of the AGDS data and interpreted sidescan images for comparison with unsupervised classification. Both AGDS gave similar outputs, although RoxAnn consistently gave slightly better levels of performance than QTC-VIEW as measured using error matrices. Although the investigation was not designed to compare the performance of AGDS and sidescan, the outputs from AGDS were similar to the visual interpretation of the sidescan sonar data. It was concluded that despite the inherent limitations of AGDS, they may be suitable for providing distribution maps at a broad scale that can give a context for the interpretation of finer scale survey of smaller, nested areas.

Slope Water anticyclonic Oceanic eDDIES (SWODDIES) are typical mesoscale features of open-ocean waters of the southern Bay of Biscay which usually develop in winter by shedding from the seasonal poleward current flowing along the northern Spanish slope. These eddies have been intensively studied from the physical perspective. However, their effect on the distribution of biological properties and on the functioning of the pelagic ecosystem has not been assessed so far. To this aim, a sea-truth, multidisciplinary and comprehensive study of a SWODDY was carried out in summer 1998. The eddy, radius of ≈50 km, was initially centred at 45·5°N 6·0°W, being characterized by a relatively homogeneous core of water in the centre of the eddy extending from 80 to about 200 dbar. In the central region of the core, temperature (12·55–12·75°C) and salinity (≈35·70) values were higher than outside the eddy. The optical properties of the eddy also differed from those of the surrounding waters. A distinct biological signature was found associated with the eddy. Depth-integrated chlorophyll-a concentrations were 25% higher at the eddy centre where upward doming of the seasonal pycnocline (up to 30 dbar) occurred. Enhanced phytoplankton biomass was related to a higher contribution of >10 μm cells, mainly represented by diatoms and chrysophyceans. Phytoplankton and mesozooplankton species composition in and outside the eddy differed significantly reflecting the coastal origin of the water parcel trapped by the eddy. The sharp modification of the planktonic community composition, biomass and associated size-structure caused by slope water oceanic eddies are likely to exert a significant effect upon the upper trophic levels of the pelagic ecosystem of the southern Bay of Biscay.

The population dynamics in the coastal bacterioplankton community off Plymouth (UK) was studied in samples proportionally diluted (99%, 90%, 66% and 0%) with sterile seawater, incubated in the dark for 2–4 days and monitored by flow cytometry. Nucleic acid content of cells, stained with SYBR Green I DNA specific dye, was used as an index of a genome size. Using flow sorting and fluorescence in situ hybridization (FISH) with a set of ribosomal RNA targeted oligonucleotide probes, the phylogenetic composition of dominant cytometric groups of bacterioplankton was determined to be similar during growth in the dilution series. The proportion of the low nucleic acid (LNA) group decreased and correspondingly the high nucleic acid (HNA) groups increased with dilution. The assimilation rates of free amino acids, a highly labile nutrient pool, were determined by flow sorting the dominant groups after short incubations with 35S-methionine tracer. The relative cellular amino acid assimilation by the LNA cells increased with dilution, while the activity of the HNA cells either decreased or remained unchanged. However, highly metabolically active LNA bacteria were overgrown by the HNA bacteria, presumably because the small genome size—an adaptation to living in an oligotrophic environment—did not allow the LNA group to grow sufficiently fast to compete with the HNA group under experimentally reduced grazing pressure. To examine the experimental results a numerical model of bacterioplankton population dynamics was formulated based on the hypothesis that the LNA cells consume only a labile fraction of organic nutrients (amino acids etc.), while the HNA cells feed on both the labile and more refractory sources of nutrients, and that in the absence of phytoplankton the labile source of nutrients is produced entirely by the bacterivorous flagellates. The model simulations gave credence to the hypothesized primary dependence of the LNA group on labile organic nutrients recycled within the microbial loop.

Crab-baited traps, with a 5-mm diameter opening, were deployed 90 mm off the seabed monthly at Lobster Bay, Hong Kong, for one year between 1998 and 1999. Visitors drawn to the traps were mainly species of Ceradocus (Gammaridea: Melitidae), Tisbe (Harpacticoida: Tisbidae) and Nebalia (Leptostraca: Nebaliacea). Apart from Ceradocus sp., all were scavengers with catches using baited traps significantly exceeding unbaited controls. Ceradocus sp. was apparently drawn to traps for refuge. The trapped scavenger community composition changed with deployment duration in the presence of bait. Nebalia sp., Neanthes cricognatha (Polychaeta: Nereidae) and Lepedepecreum sp. (Gammaridea: Lysianassoidea) were identified mostly two/three-days post-deployment, exhibiting a potential preference for rotten organic matter. Seasonal catches were also identified for all three visitors with maxima between October 1998 and April 1999. Such seasonal patterns might be related to either turbulence destabilizing the substratum during this period or life cycle patterns in the study area.

The near-bottom mesozooplankton was caught by a four net suprabenthic sledge on six sites in the English Channel during both spring and autumn. Taxa richness showed no significant difference between seasons, nevertheless diversity (H′), evenness (J) and normalized rarefaction number of taxa E(S91) were higher in autumn than in spring at each site except at Site 2 offshore Plymouth, where Calanus helgolandicus dominated at both seasons. Copepods dominated in abundance at each site in spring while crustacean larvae were dominant in autumn except at Site 2 offshore Plymouth, where copepods remained dominant and, at Site 6 in the Dover Strait, where no significant difference occurred between copepod and crustacean larvae abundances. Four assemblages were distinguished depending on the season. Abundance was higher during the day than at night as a result of a mesozooplankton concentration in the near-bottom layer during the daytime. Moreover, three vertical patterns of suprabenthic mesozooplankton were identified according to their distribution above the near-bottom layer: taxa distributed homogeneously in the four nets; taxa concentrated in nets 2 and 4, and taxa concentrated in the three upper nets.

Meiobenthic community structure was investigated at different spatial scales (from 100 metres to centimetres) on and adjacent to a group of coral-topped sandy mounds in the bathyal north-east Atlantic (Darwin Mounds, Rockall Trough) and related to the environmental conditions in the area, mainly differences in sediment organic carbon content and presence of biogenic structures. Meiobenthos abundances were similar to those observed in other deep-sea sites, with nematodes representing at least 94% of the total community. The dominant nematode genera were Microlaimus, followed by Sabatieria, Richtersia, Rhynchonema and Trefusia, together with typical deep-sea genera (e.g. Halalaimus and Acantholaimus). Multivariate analysis of nematode generic relative abundances at the different stations indicated that there was no significant influence on distribution resulting from large scale topographic and biogeochemical conditions around the mounds. The same genera were associated with dead tests of the xenophyophore Syringammina fragilissima and in the surrounding sediments. The vertical distribution of nematodes on and adjacent to the mound showed some unusual features, as the deeper layers of the sediments were inhabited by stilbonematids. These genera harbour ectosymbiotic, chemoautotrophic bacteria and have not previously been recorded from the deep sea. The occurrence of stilbonematids in notable numbers in the subsurface layers of the sediments in the vicinity of the Darwin Mounds provides evidence for the occurrence of anoxic microenvironments.

Benthic assemblages of two Mediterranean submarine caves were compared. Species coverage and number of species were lower in internal (dark) communities than external. This feature was specially marked in the less illuminated cave. Ordination analyses performed on species coverage per community for each cave separately, distinguished several benthic communities from the outermost to the innermost zone of each cave. Cluster analyses on species coverage, taking into account all communities in both the caves, established similarities among communities: algal-dominated communities clustered according to the level of light received independently of the cave they inhabited, while animal-dominated communities were more similar within each cave than between the caves. Moreover, among the abiotic parameters measured irradiance was the only factor that clearly diminished from the entrance to the innermost zone in both the caves. In contrast, water movement and particulate organic matter varied differently in each cave. Results indicate that the different topography, depth and geographic location of the two caves determine water movement, light penetration and nutrient availability along the caves. These factors are responsible for determining species abundance and diversity, as well as species growth habit in each community.

The structural parameters of sponge-dominated benthic communities from two Mediterranean caves in two seasons, autumn (November) and spring (June) were compared. The percentage of species in common between communities in each cave was calculated as a rough estimate of the capacity of species dispersion in each cave. The Shannon diversity index and Kulczynski similarity index were calculated for each community. Moreover, we studied the spatial distribution, patchiness and interspecies contacts of the most abundant species. The value of α-diversity was quite constant among communities of the Cabrera cave but decreased from the external to the innermost community in the Medes cave. The Kulczynski similarity index was generally lower among samples of the Cabrera cave. The most abundant sponge species showed a predominantly clumped distribution, especially in the most internal communities of the two caves. The innermost community of the Medes cave had the highest number of patches. Finally, the study of contacts among species that were non-random (meaning species that were in contact with a given species significantly more or less frequently than expected) showed that they were very common in the two seasons and in all communities, indicating the importance of biotic associations among benthic species in cave assemblages.

The influence of sedimentation, depth and substratum angle on sponge assemblages in the Wakatobi region, south-eastern Sulawesi, Indonesia was considered. Sponge assemblages were sampled from two reef localities. The first reef (Sampela) was highly impacted by high sedimentation rates with fine sediment particles that settle slowly, while the second (Hoga) experienced only fast settling coarse sediment with lower overall sedimentation rates. Sponge assemblages were sampled (area occupied and numbers) on the reef flat (0 m) and at 5 (reef crest), 10 and 15 m (15 m at Hoga only). Some significant (P<0·001) differences were observed in the area occupied and the number of sponge patches between surface angles and sites. Significantly lower (t>4·61, df=9, P<0·001) sponge numbers, percentage cover and richness were associated with the reef flat at both sites compared with all other depths at each site, with the exception of abundance of sponges on the reef flat at Sampela, which was much greater than at any other depth sampled. Species richness increased with depth at both sites but differences between surface angles were only recorded at Sampela, with higher species richness being found on vertical, inclined and horizontal surfaces respectively. A total of 100 sponge species (total area sampled 52·5 m2) was reported from the two sites, with 58 species found at Sampela and 71 species at Hoga (41% of species shared). Multi-dimensional scaling (MDS) indicated differences in assemblage structure between sites and most depth intervals, but not substratum angles. A number of biological (e.g. competition and predation) and physical (e.g. sedimentation and aerial exposure) factors were considered to control sponge abundance and richness. Unexpectedly a significant (F1,169=148·98, P<0·001) positive linear relationship was found between sponge density and area occupied. In areas of high sponge coverage, the number of patches was also high, possibly due to fragmentation of large sponges produced as a result of predation and physical disturbance. The MDS results were also the same whether sponge numbers or percentage cover estimates were used, suggesting that although these different approaches yield different sorts of information, the same assemblage structure can be identified.

Fourteen rare or poorly known sponge species have been found in the Aegean Sea. The species Pachastrissa pathologica, Calthropella stelligera, Weberella verrucosa, Aaptos papillatus, Timea geministellata, Spiroxya heteroclita, Clathria translata, Hymedesmia simillima, Mycale serrulata, Myrmekioderma spelaea, Callyspongia septimaniensis and Ircinia pipetta are new records for the eastern Mediterranean while the species Geodia barretti and Petrosia vansoesti are reported for the first time from the Mediterranean Sea. Information on their morphology, geographical and bathymetrical distribution is given and discussed.

Three colonies of warm-water coral Astroides calycularis were found at the eastern part of the middle Adriatic Sea during the 1990–2001 period. For each specimen, depth distribution and habitat were recorded. Previous and recent knowledge of this species in the Adriatic Sea and in the Mediterranean Sea was discussed in relation to climatic changes. Occurrence of A. calycularis in the Adriatic Sea was related to the increased temperatures of the surface marine layer. Variable temperature conditions were connected to the climatic changes on the hemispheric scale through the North Atlantic Oscillation index. The prevailing sea current system together with the coastal configuration and bottom type favours the presence of the studied warm-water coral on the eastern Adriatic coast.

The hypothesis investigated in this paper is that the interstitial polychaete Saccocirrus sonomacus is excluded from beaches impacted by tailing disposal as a result of the blocking of the interstitial space and not by a response to the toxicity of elevated copper concentrations. Field evidence suggested that abundances of S. sonomacus on beaches where they would be expected to occur under natural conditions are lower when a beach has received a significant amount of tailings. In choice experiments, S. sonomacus always preferred an open coarse sand matrix to one where the interstitial spaces had been blocked by fine sand (a tailings substitute). Using invitro bioassays, we found that the LC50 for S. sonomacus with copper was 44 μg Cu l−1, this being higher than the values of interstitial labile copper measured on the beaches investigated in this study. We therefore accept the hypothesis of a physically mediated exclusion rather than a toxically mediated one.

Diel vertical migration (DVM) and distributional patterns of copepods collected in the water column at shallow water site (Station M) in Tanabe Bay, Japan were investigated. Twenty-one taxa of zooplankton and 48 species of copepods at Station M had positive ΔZ values (subtraction of night-time weighted mean depth from daytime value) and performed normal DVM. The highest ΔZ value was 4·3 observed in Ambunguipes rufocincta. Three taxa and 39 species collected only at night also had high WMD (weighted mean depth) values (4·0∼7·5), which were previously considered hyperbenthic species. Statistically significant differences were found only in Myodocopina spp., Calocalanus plumulosus and Clausocalanus spp. Myodocopina spp. and Clausocalanus spp. showed downward migration at low to high and high tidal phases. Calocalanus plumulosus and some copepods performed downward migration during high and high to low tidal phases. Four distributional patterns of copepod species in Tanabe Bay were found. The groups are as follows: (A) true planktonic group; (B) swarming and night emerging group; (C) night emerging meiobenthic and hyperbenthic group; (D) symbiotic and night emerging group.

Interannual and spatial differences in the abundance of Metridia lucens are reported from the Irish Sea from 1996 to 2001. In most years the abundance in spring is very low (<50 m2), however in 2001 the abundance was high and this enabled a rare study of the vertical distribution of M. lucens in coastal waters. The vertical distribution differs with time of day and water column structure. Abundances were always higher in stratified deeper waters compared with mixed or coastal waters.

This is the first record of the epizoic barnacle (Octolasmis angulata) on the crab Charybdis feriatus. Prevalence of O. angulata was 85·7% and mean intensity of infestation was 59±64·5 (range 3–239). Prevalence and mean intensity of infestation increased with host size in the range 55–120 mm carapace width. Barnacles occurred most frequently on the gills, anterior branchial chamber wall in the epibranchial space, occasionally on the wall of the branchial chambers beneath the gills and on the scaphognathite within the branchial chambers. Most barnacles were observed on the hypobranchial surface of the gills.

A recent inventory of the benthic Gammaridea: Amphipoda species on the French continental coastline catalogued 495 species. An analysis of the biodiversity and the biogeographic relationships that exist between the French Amphipoda: Gammaridea, living on the coastline that extends along 10° latitude range in the temperate region between 41° and 51° North and the other gammaridean faunas living in the north-eastern Atlantic has drawn the pattern of diversity in this marine invertebrate group on a large biogeographical scale. Gammaridean amphipods exhibit a latitudinal gradient over the total number of species, including the continental shelf species and the bathyal species. There are four main fauna groups, which correspond to the biogeographical zones of the north-eastern Atlantic: (1) a cold arctic and cool-temperate Svalbard and Norwegian coastal fauna; (2) a cool-temperate boreal and Boreal–Lusitanian United Kingdom, Irish and English Channel shallow fauna; (3) a warm-temperate Lusitanian Bay of Biscay and subtropical central Atlantic fauna; and (4) a subtropical Mediterranean fauna. The French fauna appears particularly rich, presenting 44% of the 1119 species recorded in the north-eastern Atlantic along the 50° latitude range (30°N–80°N).  

This is obviously due to France's intermediate latitudinal location within the Lusitanian temperate biogeographical zone, which produces a biogeographical cross between the boreal fauna in the north and the warm temperate and sub-tropical fauna in the south.

In a benthic mesocosm experiment, the effects of two species of burrowing Thalassinidean shrimps (Callianassa subterranea and Upogebia deltaura) on rates of sediment denitrification were determined using the isotope pairing technique. Denitrification rate (Dtot) and coupled nitrification–denitrification (Dn) were shown to be significantly enhanced by the presence of U. deltaura by 2·9 and 3·3 times respectively, relative to control measurements. For U. deltaura the stimulation of the denitrification rate was found to be significantly related to the size of the animal (F=5·81, P=0·042). No deviation from the rates determined in control cores for either Dtot or Dn was observed for those cores inhabited by C. subterranea. The increase in Dtot with U. deltaura was considered to be the result of a combination of different factors, including; the direct extension of the sediment–water interface and an increase in oxygenation of the sediments and solute transport, as a result of the ventilating activities of the animal itself.

The densities of two common intertidal/shallow subtidal bivalves, Soletellina alba and Arthritica helmsi, were sampled in vegetated and unvegetated habitats of the Hopkins River estuary on three occasions during the autumn/winter 1995. Winter flooding coincided with mass mortalities of the infaunal bivalve S. alba, but not A. helmsi. Mortalities were apparent for individuals living deeper in the sediment (≈35 cm) in vegetated and unvegetated habitats, but small S. alba (<1 mm) were less susceptible to mortality than larger individuals (>1 mm). Mortalities were similar across different habitat types and sediment depths, and at multiple sites within close proximity to the estuary mouth.

The comparison of metal handling strategies in mussels Mytilus edulis and oysters Crassostrea gigas was based on the translocation of these bivalves from a relatively clean site (Bay of Bourgneuf, France) to the metal-rich Gironde estuary, France, whereas resident oysters from the Gironde estuary (feral mussels were absent from this site) were cross-translocated to the clean site for seven months (March to October 1997). Higher levels of metal concentrations (Ag, Cd, Cu, Zn) were observed in specimens from both species in the Gironde estuary. However, no cellular pathology was observed, even in translocated mussels which are not normally present in the studied zone of the Gironde estuary. These observations show that both species cope relatively well with the conditions prevailing in the metal-rich estuary, at least partly as a result of the insoluble storage of bioaccumulated metals in well-defined and localized bioaccumulation structures such as mineralized lysosomes in the kidney of mussels and the digestive gland of both species and granules concentrated in extracellular basal lamina. For both species, recruitment of spat was observed on artificial substrates immersed near the site of translocation in the Gironde estuary. The absence of adult mussels in the metal-rich Gironde estuary may be due to competition with oysters for free surfaces of settlement as well as predation by crabs.