The bed-forming brittlestars Ophiothrix fragilis, Ophiocomina nigra and Amphiura chiajei from Oban Bay, Scotland were studied using methods previously employed to study chemoautotrophic symbioses. Ophiothrix fragilis and A. chiajei both contain symbiotic bacteria (SCB) while Ophiocomina nigra is non-symbiotic. Samples were taken of Ophiothrix fragilis at approximately two-week intervals for one year. Symbiotic bacteria numbers were determined by direct counting of homogenates of the arms of 50 individual brittlestars. Water samples were analysed for chlorophyll content. Stable isotope ratios for carbon and nitrogen were determined for each homogenate sample. Regular SCB counts were made on the infaunal brittlestar A. chiajei. Homogenate samples of Ophiothrix fragilis, A. chiajei and the non-symbiotic Ophiocomina nigra were analysed to produce fatty acid profiles for each species. Symbiotic bacteria count varied by up to one order of magnitude in both Ophiothrix fragilis and A. chiajei with no evidence of seasonality in this variation. Symbiotic bacteria number was inversely correlated with δ15N but no relationship was established with δ13C. 16:1ω7 and 18:1.ω7 fatty acids were used as putative bacterial markers. Both symbiotic species had higher percentages of 16:1ω7 than the non-symbiotic Ophiocomina nigra. However, only Ophiothrix fragilis appeared to receive appreciable quantities of 18:1ω7 from its SCB. The SCB are heterotrophic and may contribute to the nitrogen budget of the host. The two symbiotic species studied here derive the bulk of their nutrition from conventional feeding but SCB make significant, additional contributions.

Upper critical thermal limits were measured as heat coma temperatures in Littorina species (Mollusca: Gastropoda) from sites around the British Isles. Thermal tolerance was found to be stable within a population but extensive variation occurred between populations and species. The majority of species examined displayed heat coma values of around 30°C and did not show a positive correlation with shore height. The highest capacity for thermal tolerance was found along the coast of South Wales, while the lowest was found on the south-west coast of Ireland and on the east coast of Scotland.

The aim of this study was to characterize the daily shell growth of Pecten maximus from early 1998 to late spring 1999 in the Bay of Brest with a careful qualitative and quantitative description of the pelagic primary production. Our results, in accordance with previous studies, demonstrate that there are episodic declines in the growth rate. Concurrent events of low growth rate and large bottom-concentrations of algae following diatom blooms (Cerataulina pelagica or Rhizosolenia delicatula), suggests that this high concentration of phytoplankton on the bottom layer may affect food intake or respiratory activity of the scallops by gill clogging or oxygen depletion. In this study, silicic acid or phosphorus are inferred to be limiting factors responsible for the collapse of the spring bloom. Further, we suggest that, in an N-enriched ecosystem, Si or P-limitation and the changing sinking velocities of phytoplankton, could affect the biology of benthic suspension-feeders.

Hermit crab populations have been described in different habitats and latitudes but few studies focused on coexisting populations. Such information is especially important to evaluate the effect of coexistence in the population biology of such organisms. This study was done in the intertidal region of Pernambuco Islet, São Sebastião Channel, south-eastern Brazil. Random samples of crabs were taken monthly during one year to evaluate their size and sex. The three coexisting Clibanarius populations (C. antillensis, C. sclopetarius, and C. vittatus) showed similar patterns of sex ratio (skewed for females), sexual dimorphism (males larger than females), recruitment (February to June) and population growth but differed in size structure (Cs>Cv>Ca) and reproductive activity over the year. Population growth was estimated using the von Bertalanffy growth function (VBGF) and revealed that the growth of these three populations was strongly reduced from August to January and that longevity varied from 42 to 48 months. Clibanarius antillensis showed continuous reproduction with high frequency of ovigerous females over the year while C. sclopetarius and C. vittatus had a reproductive peak in April and absence of ovigerous females in August/September. Coexistence seemed to influence population biology of these hermit crabs, given the relationship of their reproductive periods and growth patterns to the shell adequacy to the crabs. The overlap in reproductive peaks and recruitment periods may strengthen competition for shells. Comparisons of the reproductive patterns of the hermit crab populations recorded to date emphasize that reproduction and, consequently, life strategies of hermit crabs are not directly dependent on taxonomic or geographical proximity, but on their evolutionary histories and on local processes acting on each assemblage or population.

Eicosanoids are oxygenated derivatives of C20 polyunsaturated fatty acids known to play key roles in many physiological events in both invertebrates and vertebrates. The eicosanoid generating capacity of cypris larvae of the barnacle, Balanus amphitrite, was examined using enzyme immunoassay and high-performance liquid chromatography. These larvae generated the lipoxygenase products, 12-hydroxyeicosapentaenoic acid (HEPE), 8-HEPE and 8,15-diHEPE, together with the cyclooxygenase products, prostaglandin (PG) E, PGF and thromboxane (TX) B. Indomethacin, a selective cyclooxygenase inhibitor, caused a dose-dependent inhibition of PGE generation by B. amphitrite larvae, while esculetin and nordihydroguaiaretic acid (lipoxygenase inhibitors) also strongly inhibited the generation of 8-HEPE, 12-HEPE and 8,15-diHEPE. PGE2, PGE3 and 16,16-dimethyl PGE2 caused a dose-dependent inhibition of settlement of B. amphitrite larvae while indomethacin (25–100 μM) stimulated this process. Lipoxygenase products (8-HEPE, 12-HEPE and 8,15-diHEPE) as well as esculetin and nordihydroguaiaretic acid (10–100 μM) had no effect on the attachment of larvae.

Five species of bresilioid shrimp were investigated at seven hydrothermal sites on the Mid-Atlantic Ridge: Menez Gwen, Lucky Strike, Rainbow, Broken Spur, TAG, Snake Pit and Logatchev. Samples were prepared for analysis of stable isotopes, elemental composition and lipids. Shrimp behaviour was observed from the submersible ‘Alvin’ and in the laboratory aboard RV ‘Atlantis’. The distribution and zonation of the shrimp species was recorded. Juvenile shrimp of all species arrive at the vents carrying reserves of photosynthetic origin, built-up in the pelagic larval stages. These reserves are used while the shrimp metamorphose to the adult form and, in Rimicaris exoculata and Chorocaris chacei, while they develop epibiotic bacteria supporting structures, the modified mouthparts and the inside of the carapace. The main food of adult R. exoculata is filamentous bacteria that grow on these structures. The intermediate sizes of C. chacei also feed on such bacteria, but the final stage gets some food by scavenging or predation. Mirocaris species scavenge diverse sources; they are not trophically dependent on either R. exoculata or mussels. Adults of Alvinocaris markensis are predators of other vent animals, including R. exoculata. The dense swarms of R. exoculata, with their exosymbionts, can be compared to endosymbiont-containing animals such as Bathymodiolus and the vestimentiferan tube-worms of the Pacific vents. Such associations, whether endo- or ectosymbiotic, may be necessary for the development of flourishing communities at hydrothermal vents.

The magnitude of geographical variations of stable isotope ratios of carbon and nitrogen was examined in ten squid species captured in seven areas of the world's oceans. The average of all 139 squid was −17.4±1.4‰ for δ13C and 11.6±1.6‰ for δ15N. The δ13C of squid showed a clear-cut negative correlation with the latitude of the sampling locations, reflecting the well-known latitudinal characteristics of phytoplankton δ13C, while squid δ,15N did not correlate with the latitude significantly. The δ15N reflected the regional characteristics of nitrogen metabolism such as denitrification and N2 fixation, and it was conspicuous in the intraspecific variation in Sthenoteuthis oualaniensis ranging from 10.0±1.5‰ off Japan to 16.3±0.6‰ off Peru in the Pacific Ocean. Significant isotopic variations were also found in the local area among the five species off Japan in the Pacific Ocean and among the three species in the Japan Sea. Attention must be paid to the isotopic variations of primary producers as well as those of squid in examining the trophic positions of squid.

Mussel seed Mytilus galloprovincialis (Bivalvia: Mytilidae) from two origins (rocky shore and collector ropes) was cultivated on a raft in the Ría de Arousa (north-west Spain), from seeding to thinning out, for 226 d (November 1995–July 1996) and two aspects of metabolism, oxygen consumption rate (VO2) and ammonia excretion rate (VNH4-N) were studied in situ.

The model derived from multiple analysis of oxygen consumption accounted for 91.9% of the variance, based on dry weight of the mussels and the environmental factors quality of food (organic content) and mainly chlorophyll-a. Seed origin also showed significant influence. The seasonal pattern of the oxygen consumption can be attributed mainly to the variation of chlorophyll-a, which showed a higher range of values in the spring months.

Origin of seed did not show a homogeneous effect on oxygen consumption throughout the cultivation period. Collector rope mussels showed higher oxygen consumption values at the beginning of the cultivation period and after the first 15 d, but the rocky shore mussels showed a higher oxygen consumption between days 22 and 110. Energy-conserving patterns and lower condition index at the onset of the experiment for rocky shore mussels could explain these initial differences.

Multiple analysis on the variation of ammonia excretion rate provided a model that accounted for 72.6% of the variance based on dry weight of mussels, seed origin and the environmental parameters chlorophyll-a and total particulate matter. The rocky shore mussels showed a significantly higher excretion values for most of the cultivation period, although there was no constant tendency throughout. High excretion values were recorded between January and March, whilst for the rest of the cultivation period values were low.

The O:N index was higher in collector rope mussels for most of the cultivation period, which may suggest a more favourable energy metabolism and/or a more appropriate nutritional state for these specimens.

Temporal evolution of the ingestion and absorption rates of organic matter and biochemical components in the filter-feeding bivalve Cerastoderma edule (Mollusca: Bivalvia) fed for 12 d on the same ration (1.5 mm3 l−1) of the microalgae Tetraselmis suecica (Chlorophyta: Prasinophiceae) having different biochemical composition, were measured. Cockles in group E were fed algal cells harvested at the exponential growth phase (55.5% of protein, 16.8% of carbohydrate and 27.6% of lipids) whereas cockles in group S were fed cells harvested at the stationary growth phase (45.3% of protein, 35.2% of carbohydrate and 20.0% of lipids). After the feeding period cockles were submitted to starvation and biochemical analysis of faeces produced during final steps of gut evacuation (after 24–96 h of starvation) was performed to estimate biochemical composition of metabolic faecal losses (endogenous matter lost during the process of digestion).

Ingestion rate of organic matter was found to gradually increase during the feeding period in both groups. Absorption efficiency of organic matter decreased but reached an asymptotic minimum with rising ingestion rate. This relationship resulted in a gradual enhancement of absorption rate of organic matter over the time. Lipid fraction of food was found to be absorbed with significantly lower efficiency (even negative values were recorded in group S) than proteins and carbohydrates irrespective of the diet. Endogenous faecal losses presented high proportion of lipids (up to 66%) and lower proportions of proteins (∼25%) and carbohydrates (∼9%). On the other hand, increasing carbohydrate abundance in the diet brought about no apparent enhancement of carbohydrates absorption efficiency. Results are discussed in relation to the time-course of digestive enzyme activities.

A new holothurian species Chiridota hydrothermica (Apodida: Chiridotidae) is described, restricted to hydrothermal vent habitats. The new species is known from the west Pacific (Manus and North Fiji Basins) and the South East Pacific Rise, between 17 and 21°S. The unusual large, lobe-like tentacles of this holothurian, uncommon in the family Chiridotidae, could be an adaptation to facilitate shifts between suspension- and deposit-feeding in the hydrothermal environment. A brief review of all known records of holothurians and other echinoderms at hydrothermal vents is given.

The first results of the females reproductive cycle of Maja brachydactyla (Braquiura: Majidae) off the coast of Asturias (north-west Spain) are presented. Mean size of mature females was 133·4 mm (N=1022) in 1997 and 125·0 mm (N=942) in 1998. Only one cohort is exploited each fishing season. This cohort passed through the terminal moult the year before and recruited in to the fishery beginning in June. The breeding cycle off the coast of Asturias begins in December and ends in November the following year. Results from this study indicate that females produce 3–4 broods per year in these waters, which is the highest reported number for M. brachydactyla. The results are discussed in terms of their importance for management of the fishery.

The movement of juvenile Iceland scallops, Chlamys islandica, was quantified in an inshore bed in the Mingan Islands, northern Gulf of St Lawrence, to examine whether the size partitioning over depth in this location, increasing scallop size with depth, results from a gradual downslope movement as scallops increase in size. Scallops of 30.0-44.9 mm and 45.0-59.9 mm in shell height were collected using SCUBA, tagged, and released in the centre of two 0.4-km2 grids at 15 m in depth. After 7 d and 48 d, the net distance moved by the scallops from the release points did not vary between the two size groups but varied significantly between grids. The majority of scallops (70-94%) moved downslope and the mean movement vectors were not orientated in the direction of tidal currents, but rather towards increasing depth. The downslope movement of the scallops was possibly explained by more prolonged swimming bouts when scallops swam downslope. The results suggest that the spatial size partitioning of Iceland scallops at this location is caused by a gradual downslope movement as the scallops increase in size. This study provides the first experimental evidence supporting the controversial hypothesis of recruitment into adult scallop populations involving swimming of juveniles from nursery areas.

During three consecutive years of observation 23 Atlantic cod (Gadus morhua) were tagged with ultrasonic transmitters as part of two experiments to determine the movement patterns of adult cod in the genetically distinctive population inhabiting Gilbert Bay, Labrador. Individual cod were relocated for periods up to 15 months, indicating year-round residency within the bay despite unimpeded access to the open ocean. The tracking data show that individual cod have a strong homing tendency. In experiment 1 displaced cod returned (homed) to their place of capture in a small arm separated from the rest of the bay by a shallow sill while non-displaced fish remained at their capture site. In experiment 2 some cod remained within 2 km of their capture/release site, a spawning area, while others ranged widely in Gilbert Bay before returning to this site. Whether an individual ranged widely or had more restricted movements was not related to size. Cod exhibited wider ranging movements in the spring and early summer, following spawning, than in the late summer and early autumn. The return of Gilbert Bay cod to specific locations in the inner part of the bay to overwinter and spawn is evidence of one mechanism that could have led to their genetic distinctiveness.

Early life growth of the short-finned squid, Illex illecebrosus (Mollusca: Cephalopoda), was reconstructed from periodic increments deposited on the gladius structure of squid collected in the Gulf Stream/Slope Water front and the Scotian Shelf. The general effects of environmental changes and lifestyle transitions in the variation of size-specific gladius growth was investigated. The offshore growth was exponential and at least six size-specific growth phases were distinguished. Paralarval growth ended at approximately 10 mm gladius length (GL). An important change in growth at 30–40 mm GL was associated with the shift from the macroplanktonic to micronektonic habitats and the transition from the Gulf Stream to Slope Water. The approximation to the Scotian Shelf/Slope Water Front was suggested as related to a growth transition at 68 mm GL. A change to linear growth occurred after the nektonic lifestyle was attained on shelf waters (90 mm GL).

The behaviour of Loligo opalescens as observed by a remotely operated vehicle (ROV) was analysed. Thirty-nine behavioural components were identified and classed into four categories: chromatic, postural, locomotory, and inking. The frequency with which components were expressed was correlated to whether or not an individual was schooling, shoaling, alone with the ROV, or in the presence of other species. Behaviours observed were compared to those reported for other Loligo species. Observations of schooling and feeding behaviour, and reactions to other species are included.

The distribution and relative abundance of macroepibenthic echinoderms in the eastern English Channel and Irish Sea is described from beam trawl catches. Echinoderms accounted for approximately 29% (by biomass) of fauna captured. A total of 24 species were recorded, including 12 species of starfish. The most frequently encountered species were Asterias rubens and Psammechinus miliaris, which were recorded at 85.5% and 56.0% of stations respectively. Asterias rubens and Ophiothrix fragilis accounted for 63.7% and 25.5% (by biomass) respectively of the echinoderms sampled. Mean echinoderm catches ranged from 0.8-kg h−1 in the north-eastern English Channel to 329-kg h−1 in the south-eastern Irish Sea. The echinoderm fauna was more diverse in the St George's Channel and western Irish Sea (6.7–7.0 species haul−1) than in the north-eastern English Channel (1.9 species haul−1).

Lancelets of the genus Branchiostoma (amphioxus) are widespread and locally abundant filter-feeding animals in shallow coastal waters of the south-eastern US (up to 5000 ind/m2) and in temperate and tropical seas worldwide (up to 9000 ind/m2). Lancelets are consumed by bottom-dwelling fish and humans. As part of a larger project to aquaculture lancelets, an experiment was conducted to determine the range of diameters of suspended particles filtered and ingested by the Florida lancelet, Branchiostoma floridae (Chordata: Cephalochordata). After a period of starvation, animals were exposed to a suspension of tracer particles of seven different diameters (range 90–0.062 μm) and the protein, ferritin (0.012 μm) and their faeces were examined subsequently for the presence or absence of tracer. Particles ranging from 90–0.062 μm, but not ferritin, were filtered and ingested. Many of the 90 μm diameter particles, however, were excluded from entering the body by the oral cirri. Under experimental conditions, B. floridae filters and ingests particles in the range of ∼100–0.062 μm (microplankton to colloidal particles). This result suggests that the lancelet diet, like that of appendicularians, includes microbial as well as phytoplankton production.

The cirrate octopod family Stauroteuthidae is revised on the basis of new material collected from the North and South Atlantic and a thorough examination of relevant type material. The family is characterized by the presence of a secondary web, U-shaped shell vestige, reduced mantle aperture and with long cirri, not reaching the arm tips. The radula is absent. The family contains a single genus with two valid species, Stauroteuthis syrtensis and S. gilchristi, which are redescribed based on the holotypes and new material. Chunioteuthis ebersbachii is a junior synonym of S. syrtensis and C. gilchristi is placed in the genus Stauroteuthis. The genus Chunioteuthis is no longer valid. The form and arrangement of suckers distinguish the two species of Stauroteuthis. Stauroteuthis syrtensis is broadly distributed in the North Atlantic at depths of 700—4000 m with peak abundance at 1500—2500 m. Stauroteuthis gilchristi is known only from the type locality off Cape Town (2604 m) and from new material captured off South Georgia (1000 m).

The growth of Octopus vulgaris (Mollusca: Cephalopoda) in tanks and the sea was modelled and calculated following tagging studies in Senegal. Octopus exhibits a large individual variability in growth and the exponential growth curve is the best fitting theoretical model among other usual models tested. Globally, the growth rates were comparable in the sea and in tanks. Growth rates for the hot season were lower than those for the cold season. Applied to in situ data, the statistical tests showed that females grow more quickly than males. Life expectancy was estimated at between 12 and 14 months. These results question the previous growth curves for the region, all of which were obtained from modal analysis using size or weight–frequencies and were used during stock assessments of this important resource off the north-west African coast.

Different glucidic labelled compounds were used for carbohydrate metabolism exploration, tissular glycogen storage localization and amino acid uptake response to osmotic variation in the adult of Sagitta friderici.

After [1-14C] glucose or [6-14C] glucose (osmotrophic) assimilation, the relative activity of the different metabolic pathways (glycolysis–citric acid cycle and pentose cycle) have been estimated by means of a micro-radiorespirometric method. The kinetics of expired 14CO2 showed that adult Sagitta mainly used the glycolytic–Krebs cycle rather than the pentose cycle in glucose catabolism.

After 2-deoxy-D-[1-14C] glucose (osmotrophic) assimilation, tissular glycogen storages were localized. It was shown that glycogen deposits are abundant in several tissues except the locomotor muscles, which probably represent the main glucose consumers in these very active animals. The problem of glucose transport from the storage localizations to the sites of utilization has been discussed.

The L-3H-leucine uptake variations into the Sagitta body after an osmotic shock have been estimated.