A survey of benthic communities found in a heavily fished scallop ground was undertaken in July 1993. Two main faunal assemblages were identified from samples obtained with fine-meshed scallop dredges, which were grouped either in gravelly sand sediments or sandy sediment, which was generally furthest offshore in deeper water. A third assemblage was found in either sandy or gravelly muddy sand sediments. The highest abundance of small and large size-classes of scallops were associated with the assemblage containing the greatest number of species and individuals in sandy sediments. This assemblage had the greatest biomass of emergent fauna such as hydroids and Alcyonium digitatum. Data acquired from a RoxAnn™ acoustic signal processor were able to differentiate between the substratum or biotopes associated with the greatest abundance of scallops. This may provide a useful tool for refining surveys of commercial stocks or mapping suitable habitats.

Sinking of particles was measured at a coastal site near La Coruña (north-western Spain) using sedimentation traps placed at the base of the euphotic zone during four short periods between March and June 1995. In addition, measurements of water column properties and particles were made at five stations. The cases studied were representative of the main oceanographic situations that occur in this area and were related to the wind-induced upwelling. Phytoplankton blooms (> 100 mg chlorophyll−a m−2) were observed on two occasions in April and June, both during favourable upwelling conditions. The two other cases were studied during low phytoplankton biomass concentrations in the water column.

Using vertical profile data from the upwelling system off northern Chile, the slopes of dissolved oxygen/nutrient concentration regressions have been analysed, in conjunction with a value of 1·4 for the molar ratio of net community oxygen production to nitrate-driven carbon dioxide assimilation, to investigate the stoichiometric inter-relationships between photosynthetic oxygen production and carbon dioxide and nutrient consumption. There was little interseasonal variation in ΔCO2/ΔDIN (nitrate+nitrite) molar ratios, ranging from 10·3 to 11·6 in the near-shore zone of active upwelling and 6·7 to 9·0 in mid-water, between 25 and 50 m depth offshore. Although the former range exceeded the value expected from Redfield-Richards stoichiometry (6·6) by more than 50%, it was in line with published ratios for phytoplankton blooms in coastal and oceanic waters. Mean ΔDIN/ΔPO4 ratios were similar for the near-shore stations and the mid-water, ranging respectively from 7·0 to 10·7 and 8·4 to 11·5, these subRedfield-Richards values mirroring the ratios of the nutrient concentrations in the water and probably implying ‘luxury’ consumption of phosphate. Seasonal variations in the ΔO2/ΔPO4 ratios for the near-shore zone are shown to be consistent with the view that, in the austral spring and summer when upwelling is strongest in the area, the main source of the water coming to the surface is the Peru-Chile Undercurrent, whereas in the autumn, it could be of subantarctic origin.

Hydrographic measurements were made on RRS ‘Charles Darwin’ Cruise CD97 of the structure of a Subtropical Ring called STORM discovered south-west of the Azores in October 1995 which moved westward along a latitude near 32·5°N. The results showed an elliptical ring structure with a ratio of minor to major axis of 0·6. The external Ring structure extended across a scale of ~400 km in an east-west direction along the major axis of the structure. The internal structure showed isotherms (isopycnals) that were domed upwards by ~200 m. The swirl transport in the Ring was 44 Sv with a negligible barotropic component and the cyclonic flow extended throughout the water column from the surface (maximum ~50cms-1, at a radial distance of ~100km) with reduced intensity to the sea-floor ~4km depth where the flow was effectively zero. The surface currents and dynamic height data showed that the STORM centre was associated with a ~38cm lowering of sea level. The ERS-1 and ERS-2 altimeter surface signature of STORM revealed a similar structure (~42cm sea level depression) but with a larger scale of influence ~500 km. The remote sensing surface elevation structure derived from altimetry also maps (~-600X) changes in the deeper ocean temperature structure and transport (1 cm change equivalent ~ 1 Sv) in the general region. A ~500 d record from a current meter mooring deployed in the region showed three STORM signatures, each separated by a mean of ~180 days. In June 1996, HMS ‘Hecla’ crossed the North Atlantic at a latitude near 33°N and found three STORM temperature signatures.

The soft-sediment marine benthos is well-known to be patchily distributed. To test whether this could be caused by individual epifaunal movement, spatial and temporal variation in numbers of adult mudsnails, Hydrobia ulvae, were analysed within an area of 40 m2 on an intertidal mudflat over periods of 4 or 6 d on three occasions, two of spring tides and one of neap. Significant spatial variation was always present, and significant temporal variation occurred during the spring tides. There was no variation dependent on the numbers of replicate samples taken from each station. Furthermore, movement of large, individually marked winkles, Littorina saxatilis, in the same habitat was measured and shown to be significantly directional over three series of spring tides, although the mean angle of movement varied widely between the different tidal series; storm-induced movement was particularly large. Such directional movement could account for the temporal and spatial variation seen in H. ulvae. Distances moved by winkles under permanently submerged conditions, however, did not display any directional component. Estimates of the population density and dispersion of potentially mobile or movable, intertidal epibenthos obtained on a series of individual, widely spaced days must therefore be treated with caution, however much replicated on any given occasion.

Underwater television observations were made of mobile macrofauna inhabiting two parts of a sublittoral reef on the west coast of Scotland for 48 h periods in spring, summer, autumn and winter. Continuous occurrence profiles (mean hourly frequency of occurrence, %) were detailed for 12 species of fish (Chirolophis ascanii, Conger conger, Ctenolabrus rupestris, Lepadogaster candollei, Myoxocephalus scorpius, Pholis gunnellus, Pollachius pollachius, Raniceps raninus, Phrynorhombus regius, Zeugopterus punctatus, Thorogobius ephippiatus and Trisopterus minutus), ten crustacean species (Cancer pagurus, Carcinus maenas, Galathea strigosa, Homarus gammarus, Inachus spp., Munida rugosa, Necora puber, Brachyuran sp., Caridean sp. and Pagurid sp.) and four echinoderm species (Antedon bifida, Asterias rubens, Hemicia oculata and Solaster endeca). Rhythmic patterns of diel activity and/or occurrence were identified for several species. Chirolophis ascanii, Ctenolabrus rupestris, L. candollei, Myoxocephalus scorpius, Pholis gunnellus, Pollachius pollachius, Thorogobius ephippiatus, Trisopterus minutus and Munida rugosa were predominantly diurnal, but Ctenolabrus rupestris, Myoxocephalus scorpius and Trisopterus minutus also showed some evidence of crepuscular activity. Raniceps raninus activity was predominantly nocturnal but became continuous in summer. In other species (the topknots Phrynorhombus regius and Z. punctatus and the crustaceans Cancer pagurus and Homarus gammarus) identifiable occurrence patterns changed with season or site. The greatest number of fish species occurred in winter with Myoxocephalus scorpius, Pollachius pollachius and topknots (Phrynorhombus regius and Z. punctatus) showing greater occurrence/activity during spring and winter. Co-occurrence analysis was used to identify species interactions or avoidances.

Whilst evaluating the use of RoxAnn® for benthic biotope mapping it was noted that over certain visually similar sediments differences were observed in the acoustic signature. To assess this phenomenon a number of physical parameters were determined (mean sediment grain size, sediment sorting, sediment organic carbon content and the percentage of sand, silt and clay present in the substratum) from within a survey area in the North Minch. Investigation of the epifaunal and burrowing megainfaunal communities was also carried out using towed underwater television (TV) techniques. Generalized linear modelling showed that changes in Nephrops norvegicus burrow density could account for 94·7% of the variability in the RoxAnn® E1 signal. The model, however, appeared to be improved when both the percentage of silt present and the sorting of the sediment were also taken into account, with 984% of the variance in El being explained. Although improving the original model, the addition of these extra variables was, however, considered insignificant in terms of the variability accounted for by N. norvegicus density alone. The findings of this study are discussed in relation to possible shellfish management.

Simultaneous satellite and ship measurements have characterized the structure of temperature and nitrate concentration of the Shelf-Break Front of the Armorican and Celtic Sea in late autumn (November) 1985. A chlorophyll-a distribution associated with this feature is analysed in relation to the shelf-break frontal genesis and properties, and in relation to the seasonality of in situ concentrations of chlorophyll-a at the shelf-break/slope region, adjacent shelf and adjacent ocean near ~ 47·5°N.

The macrofauna of the benthic boundary layer (macrozooplankton and suprabenthos) was studied at six stations in May–June 1993 in the English Channel over sediments ranging from medium sand to pebble. The fauna collected consisted of 227 taxa in 30 suprabenthic sledge hauls. Numerically, the macrozooplankton was dominated by euphausids, chaetognaths, the holoplanktonic amphipod Apherusa spp. and fish larvae, and the suprabenthos by mysids (Anchialina agilis, Gastrosaccus spp.), amphipods (Stenothoe marina) and cumaceans at both medium sand stations. Suprabenthos species richness and diversity were significantly higher at western stations, in contrast to the pattern for macrozooplankton. The density of macrozooplankton was significantly higher, and suprabenthos significantly lower, at the western stations. The biomass of macrozooplankton was similar at the six stations, except in the middle of the Dover Strait which had a low biomass. The biomass of the suprabenthos was highest in the eastern part of the Channel. Two main assemblages were distinguished in relation to planktonic production and sediment composition: three western stations with two subgroups (stations 1 and 3 along the coasts of Brittany and station 2 off Plymouth); and the eastern stations also with two subgroups (station 4 in the Bay of Seine and stations 5 and 6 in the Dover Strait). For the macrozooplankton, two types of trophic structures could be distinguished: stations 1 and 4 where suspension-feeders dominated and the other stations (2, 3, 5 and 6) where carnivorous plankton feeders, omnivorous and scavengers predominate. For the suprabenthos, the plankton feeding, omnivorous and carnivorous trophic guilds dominated each station.

The free-living benthic copepods and nematodes in samples of decaying leaves and sediment, from a Rhizophora apiculata-dominated mangrove forest bordering the Sungai Merbok Estuary in north-western peninsular Malaysia, were identified to putative species. Analyses of community structure of these taxa revealed that both are concentrated within the surface layers of the sediment; communities associated with decomposing leaves are distinct from those associated with the sediment surface; and variation between physically similar sites within the forest is relatively small. It is suggested that the meiofaunal communities in tropical soft sediment mangrove estuaries respond primarily to salinity and exposure gradients as in temperate non-vegetated estuaries. Copepod communities of the Merbok mangrove system appear to be much more diverse than those in estuarine and saltmarsh habitats in other climatic regions, and detailed faunal analysis suggests that there is a high degree of species endemism, particularly in genera which are only found on decaying plant material.

Pyrolysis mass spectrometry (PyMS) was used to investigate the relationships of members of the genus Fucus (F. spiralis, F. veskulosus, F. ceranoides and F. serratus), and between F. spiralis and F. spiralis forma nanus. Fucus spiralis and F. spiralis forma nanus were not separable by PyMS and are thus a single species. Fucus spiralis, F. veskulosus, F. ceranoides and F. serratus were separable and their status as species confirmed. The pattern of relatedness between these species suggests a re-evaluation of their evolutionary history in that F. spiralis, F. vesiculosus and F. serratus are more similar to one another than to F. ceranoides. Pyrolysis mass spectrometry was also used to investigate the position of plants identified as putative hybrids between F. spiralis and F. vesiculosus. These plants were found to be intermediate between the two species thus confirming morphological evidence.

A new species of sponge: Higginsia ciccaresei sp. nov. (Demospongiae: Desmoxyidae) is described from a marine cave of the Ionian Apulian coast (Mediterranean Sea). It lives in complete darkness, 250 m from the cave entrance, in a basin of anchialine waters of low salinity and relatively cool temperature. The spicule formation process seems to be affected by some of the peculiar characteristics of the ambient water, resulting in spicules of unusual shape and irregular surface. This is the second record of the genus Higginsia – which has a world-wide distribution – from the Mediterranean Sea. The hypothesis that H. ciccaresei could be considered as a tethyan relic which survived in the peculiar habitat of an anchialine cave is also suggested.

The distribution of sponges (Aplysilla sulfurea, Geodia cydonium and Petrosia ficiformis) and cnidarians (Astroides calycularis, Caryophyllia inornata and Leptosammia pruvoti) was investigated in a sublittoral cave with sulphur water springs from May 1993 to February 1994 at Capo Palinuro, on the south-western coast of Italy. Multi-factorial sampling designs were used to address: (1) the distribution and abundance of sponges and cnidarians on the vault and the sides of the cave at different distances from the entrance; (2) the distribution of cnidarians on the vault of the cave with respect to the type of substratum (sponges vs others) and distance from the entrance; and (3) whether abundances were correlated with the distance from the sulphur boundary and how this relationships changed moving from the outer to the inner part of the cave. All the sources of variation included in the study affected to some degree the distribution of organisms but patterns were not consistent among species. The abundance of A. calycularis decreased proceeding from the outer to the inner part of the cave, while the reverse was observed for L. pruvoti. Differences also occurred between the vault and the sides, A. calycularis and G. cydonium being completely absent on the vertical walls. Both A. calycularis and L. pruvoti were less abundant on sponges than on other types of substratum, but patterns changed in relation to the distance from the entrance. The abundance of L. pruvoti decreased close to the sulphur boundary, while the percentage cover of A. calycularis increased, but only at outer positions. Strong variability also occurred at the spatial scale of a few metres (between replicated areas) often overriding other patterns of distribution. Results have been discussed in terms of variability in the physico-chemical environment and in the outcome of interspecific interactions.

Sixteen sponge species were recorded from Little Letite Passage, an area of highvelocity tidal currents located in the Bay of Fundy near Deer Island, New Brunswick, Canada. Of these 16 species, four species (Myxilla fimbriata, Hymeniacidon heliophila, Hemigellius sp. aff. flagellifer, and Crella rosea) have not previously been recorded from the Bay of Fundy. One new species, Hymedesmia canadensis, is described, based on the presence of a second peculiar chelate microsclere added to the spicule armament.

Trichosphaerium sieboldi is a marine amoeba with a cosmopolitan distribution. The ability of three strains, from different geographical regions, to digest a range of macroalgae was investigated. Prior to these experiments, methods were developed for the axenic cultivation of T. sieboldi. Algae included Fucus vesiculosus, F. spiralis, Laminaria digitata, L. saccharina, Mastocarpus stellatus, Palmaria palmata, Porhyra sp., and Ulva sp. All were degraded with equivalent ease; typically 50% of the tissue biomass was removed within seven days. The wall of this amoeba was studied to obtain clues on how a protist could be digesting macroalgal tissue. The fibrous nature of the outer cell wall presumably allows the wall to part and remesh during consumption of large particles. It is suggested that during digestion of macroalgae, the wall is parted to enable digestive enzymes to be localized along the surface of the seaweed wall, effectively forming an ‘enzyme pocket’. Trichosphaerium has both polysaccharidases and glycosidases, notably glucosidase, cellobiosidase, mannosidase and fucosidase. These enzymes work in concert to facilitate the breakdown of the complex polysaccharides found across the range of seaweeds used. These studies suggest that T. sieboldi could be a primary invader of seaweeds in the field. They also suggest that some protistan groups may be important in the degradation and recycling of algal material in coastal waters.

The metazoan meiobenthos was investigated in an Antarctic coastal sediment (Factory Cove, Signy Island, Antarctica). The fine sands contained much higher abundances compared to major sublittoral sediments worldwide. Classified second after Narrangansett Bay (North Atlantic) they reached numbers of 13 × 106 ind m-2. The meiofauna was highly abundant in the surface layers, but densities decreased sharply below 2 cm. Vertical profiles mirrored steep gradients of microbiota, chloropigments and organic matter and were coincident with chemical stratification. Spatial patchiness manifested especially in the surface layer. Nematodes dominated (up to 90%), and Aponema, Chromctdorita, Diplolaimella, Daptonema, Microlaimus and Neochromadora constituted almost the entire community. Overall, the nematode fauna showed a strong similarity with fine sand communities elsewhere. The dominant trophic strategies were epistrarum and non-selective deposit feeding, but the applied classification for feeding guild structure of the nematodes of Factory Cove is discussed. High standing stock, low diversity and shallow depth distribution may have occurred because of the high nutritive (chlorophyll exceeded lOOOmgm-2 and constituted almost 50% of the organic pool) and reductive character of the benthic environment. These observations must have originated from the substantial input of fresh organic matter from phytoplankton and microphytobenthic production, typical for an Antarctic coastal ecosystem during the austral summer.

The genus Podocoryna is characterized by species living on shells usually inhabited by hermit crabs; but the mutual benefits of this association are not well understood.

This study, besides describing the biological cycle of the hydroid Podocoryna exigua, brings new information on the relationship between hydroid and the hermit crab Diogenes pugilator, especially concerning their trophic strategies.

The hydroid shows a seasonal cycle with a minimum density during summer and an increase during autumn and winter, reaching the highest value in spring. The production of medusae is almost constant during all seasons. The dwelling behaviour of the hermit crab affects a particular sedimentivorous strategy of the polyps while a clepto-commensalistic strategy is adopted by the hermit crab towards the hydroid. Laboratory experiments show that the presence/absence of the hermit crab in the shell and also the seawater temperature strongly influence the number of spines, particularly structures developing from polyps. In addition, free-living polyps in the sediments may represent a strategy to colonize free shells.

Spatial analysis, laboratory experiments and field observations in the intertidal zone of La Ranee Estuary (northern coast of Brittany, France) of the infaunal polychaete Perinereis cultrifera indicate that the distribution and the abundance of this species appear to be related to the availability of cobbles. Individuals build U-shaped galleries with a surface gutter network protected by a cobble which acts as a roof. The study of spatio-temporal evolution of P. cultrifera burrows showed experimentally that density is important in space-sharing modalities within the sediment. Effects of increased density lead to modifications in the shape and size of the burrows. The absence of connections between burrows, as observed in ‘sandwich aquaria’ and in resin casts, suggest that the gallery is defended against intruders. The study of the distance between individuals in the laboratory did not reveal a regular distribution pattern. These results probably mean that the area around the burrow opening is not defended and, therefore, does not constitute a territory. Perinereis cultrifera is probably competing for burrow space while food may be shared. Territoriality is certainly the main factor involved in the organization and the spatial arrangements of individuals within a population.

Alectona species which bore into the scleraxis of several colonies of Corallium elatius and the stem of a stylasterid coral, Distichopora sp. have been studied. The genus Alectona consists of rarely collected species. Five species, of the eight known for the genus, are here recorded. Two new species of Alectona sorrentini and A. microspiculata and one uncertain species are described.

In recent reefs Cliona species are the predominant boring sponges while Alectona and Thoosa were common in the Eocene/Miocene coral reefs. The deep precious red coral communities of the western Pacific may be interpreted as refuge habitats of these ancient boring sponges.

The first data substantiating the occurrence of diarrhetic shellfish poisoning (DSP) in the central region of the Adriatic Sea (Kaštela Bay) in the summer of 1995 is presented. Toxicity was investigated using bio-assay and HPLC-FD analysis. Analysis of samples displaying toxicity, in addition to small concentrations of okadaic acid (OA), suggested the presence of an unknown derivatized compound at high concentration. A long term survey of the phytoplankton community has been conducted. The origin of mussel toxicity was traced to Dinophysis sacculus, a suspected toxic species.