The Marine Nature Reserve of Lough Hyne (south-west Ireland) encompasses an extremely wide range of marine conditions within a small area. A total of 378 boulders were collected from a range of depths at five sites subjected to very different degrees of water movement and sedimentation. Encrusting biota were identified and the communities compared between sites and upper and lower surfaces. In all, 114 taxa were identified. Alpha diversity was generally found to be higher for lower surfaces at sites with intermediate flow/disturbance. Sites with high water flow had much greater space occupation, predominantly cheilostomatid bryozoans. Multivariate analyses divided the samples into six groupings. Similarity percentage analysis (SIMPER) was used to indicate particular species characteristic of each group. Equations for the species-area curves generated tended to indicate communities at equilibrium except at sites subjected to stresses such as high sediment load or high disturbance. For high disturbance sites it was apparent that number of species cm−2 was significantly negatively correlated with surface area of rock implying non-random distribution.

The seasonal organization patterns of demersal assemblages (fish and cephalopods) in the Gulf of Lions were investigated on the basis of a set of bottom trawl surveys. The use of Partial Triadic Analysis (PTA) provided a detailed representation of: (1) the common part of the spatial organization of demersal assemblages at seasonal scale; and (2) the seasonal variability of each species around this common structure. During the course of the study, demersal assemblages exhibited a strong seasonal stability in their organization patterns and only few species showed a strong seasonal variation in their spatial distribution. Demersal assemblages of the Gulf of Lions were structured primarily on the basis of a non depth coast–open sea gradient, which occurred from the coast to the midshelf region. The influence of depth on the structure of fish assemblages appeared to be only of limited importance and mainly restricted to the continental slope area. The PTA combined with contouring technics could be used to improve our knowledge of community structuring factors, and offers a theoretical framework to assess the reproducibility of multispecies structures.

The cortical development of the marine hypotrichous ciliate Holosticha warreni, found in coastal waters near Qingdao, China, was investigated using the protargol impregnation method. In the proter, disorganization of the parental adoral zone of membranelles and undulating membranes contributes to the formation of its oral primordia which replace the parental buccal apparatus completely. Cirral anlagen in both division parts derive from the breaking of primary primordia. Most midventral cirri join in the formation of these primordia which occurs de novo separately from the oral primordia. Each of the 11 to 13 oblique streaks divides into three segments (new cirri) while the last two anlagen produce four each. Two frontoterminal cirri derive from the posteriormost anlage. The marginal rows develop from the parental structure. The generation mode of dorsal kineties is of the ‘one group type’ without forming caudal cirri.

The community structure of decapod crustacean assemblages was established and analysed from two experimental trawl samplings. The data were taken in the south-west Balearic Islands (Algerian Basin, western Mediterranean Sea) at depths ranging from ∼200 to 1800 m. The results of multivariate analysis indicate that the community structure remained constant between samplings. The analysis also revealed that there exist differences between bathyal decapod communities at a regional level (<1000 km) when compared with well-studied nearby areas. The differences relate mainly to the relative contribution of different species and feeding guilds, not to the taxonomic composition of the assemblages studied. It is proposed that these differences result from contrasting surface production regimes (coastal vs open sea) and food web organization (relative dependence on mesopelagic or infaunal prey).

The manner in which mussels, Mytilus edulis, are presented to Carcinus maenas significantly influences crab prey-selection, resulting in different foraging behaviour. Handling techniques, breaking and handling times, percentage flesh eaten and prey value curves were compared when mussels of the following size-classes, 5–10, 10–15, 15–20, 20–25, 25–30 mm shell length, were presented singly and when they were presented as part of a group to crabs of 30–55 mm carapace width. When prey were presented singly, crabs used four size-specific opening techniques; outright crushing and directed crushing were used on smaller prey whilst boring and edge-chipping were used on larger, more resistant mussels. However, when mussels were presented as part of a group, boring and edge-chipping were never observed since larger mussels were not consumed. Handling time increased exponentially with mussel size irrespective of how mussels were presented, but, when crabs fed on mussels presented as part of a group, handling times tended to be shorter than when they fed on similar-sized mussels presented singly. The median percentage of flesh left uneaten in discarded shells ranged between 9.58 and 25.25% and was significantly greater than the median percentage of flesh left in the shells of mussels presented singly, which ranged between 4.66 and 14.70%. All resultant prey value curves were convex in shape, but the predicted optimal prey size altered with modifications in prey presentation. Similarly, when crabs of 30–65 mm carapace width were presented with groups of mussels comprised of different proportions of different sizes of mussels, size-class vulnerability was not fixed but altered significantly with the relative proportions in which these were presented. Thus, when the relative number of mussels in the smaller size groups were increased so was their vulnerability, indicating that prey size preference is flexible and not fixed.

Ilyanassa obsoleta is mainly an eastern North American estuarine gastropod. Previous work on growth rate revealed a longevity of 30–40 y for this snail. Trematode infections retard growth, appear to be long-lived ([ges ]10 y) and can be frequent in this host. In 1995 a population made up of unusually large, trematode-parasitized individuals was located in Rehoboth Bay, Delaware. It was interesting to discover whether the oversized snails were the result of locally faster growth or greater age. Therefore in 1996 individually marked snails, uninfected and infected, were deployed to assess growth rates. Uninfected snails were tracked mostly in summer and autumn 1996; infected snails could be tracked longer, some through autumn 1999. Estimated growth rates of uninfected (1.5 mm y−1) and infected (0.2 mm y−1) snails in this habitat were similar to previous results and the large size of individuals in this population must be explained by greater age. Habitat history and growth rate evidence indicate the population includes snails as old as about 70 y. If correct, this becomes the greatest documented snail longevity. Trematodes gain long-term reproduction by their association with this host. By virtue of the enduring effects of long-lived individuals, and the wider potential effects of their long-lived infections (on the snails themselves and on other hosts in their life cycles), I. obsoleta stands to contribute more to the stability of coastal ecosystems than heretofore recognized.

The reproductive activity of a population of barnacle-dwelling littorinids at Peak Steel, on the north-east coast of England, was investigated. Variation in the number of mature males and females, expressed as a percentage of the whole population, showed a marked difference among the barnacle-dwelling littorinids. Littorina neglecta displayed a distinct seasonal component to its reproductive activity, with a peak in early summer. Littorina arcana B also displayed a distinct seasonal component, with a lull in the summer months. However, L. saxatilis B maintained its reproductive activity all year, but with an increase in output in the summer. The reproductive activity of both L. arcana B and L. saxatilis B follow similar patterns of reproductive activity as their typical non barnacle-dwelling forms, suggesting that these are true barnacle-dwelling ecotypes. The controversy surrounding the specific status of L. neglecta is also discussed.

The shell and internal anatomy of the montacutid bivalve Mysella verrilli is described for the first time. The species is remarkable in that the oesophagus has developed into a suctorial proboscis. This has been accompanied by the loss of the palps. In addition the gonads have been extended from the dorsal part of the body to form two gill-like extensions to which the reduced inner demibranchs attach along the postero–ventral margin. Mysella verrilli broods its young in the mantle cavity to the late veliger stage before releasing them. It is believed that the species is probably a suctorial ectoparasite on a soft-bodied benthic invertebrate.

This paper describes two new species from the genus Dorymenia (Mollusca: Solenogastres: Proneomeniidae): D. hesperidesi sp. nov. and D. menchuescribanae sp. nov., collected during the Spanish oceanographic expeditions for the study of Antarctic benthos, BENTART'94 and BENTART'95, carried out in the area of the Livingston Island (South Shetland Islands, Antarctica). A comparative study of main specific characteristics of species belonging to the genus Dorymenia found off the South Shetland Islands and in the Bransfield Strait (Antarctica), is also included.

The genetic structure of mussel recruits on a rocky shore in Nova Scotia was measured after a rare ice-scouring event which completely removed the intertidal community. Genotype frequencies were measured at three enzyme loci, phosphoglucose mutase (PGM), aminopeptidase-I (product of the leucine aminopeptidase (LAP) locus), and mannose phosphate isomerase (MPI), using cellulose acetate gel electrophoresis. The developing mussel assemblage was a mixture of Mytilus trossulus, M. edulis and their hybrids, with a greater proportion of the former species. Mussel settlers were collected for two years to examine whether genetic heterogeneity existed within and between cohorts of settlers. Settlement of mussels of both species began in April or May and continued into January. Temporal genetic heterogeneity was observed among groups of settlers, resulting from both variations in the relative proportions of the two species and from genetic heterogeneity within M. trossulus. Allele frequencies of mussel cohorts were followed from settlement to ten months post-settlement to investigate the possibility of species-specific selection and of genotype-specific selection within M. trossulus. Temporal genetic heterogeneity primarily was attributed to changes in the proportions of each species, indicating that post-settlement processes were species-specific. Early post-settlement changes were inconsistent, but later changes were clearly directional, resulting in decreased proportions of M. edulis in larger mussels in both years. There was some evidence of genotype-specific post-settlement mortality within M. trossulus, particularly during the early post-settlement period. Our results indicate that temporally variable settlement patterns and post-settlement selection interacted to produce temporal genetic heterogeneity in this mussel assemblage.

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.

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.

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.

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.

The observation in natural conditions of headless chaetognaths with healed scars and ripe gonads led us to reproduce this condition experimentally. Histological sections were made on specimens of Sagitta and Spadella at different times after beheading. The muscles contract and the gut closes the wound, so that by the end of the first two hours, the body wall and gut ‘basement membranes’ are in continuity, so restoring the integrity of the body. After two hours, the muscular layer of the body wall is reshaped and closes up the wound; the gut seals off, and a ‘clot’ is evident in the wound area. The benthic Spadella cephaloptera survives some 30 d or more after decapitation. Specimens carrying ripe ova were able to lay them, to mature and fill their seminal vesicles once or twice and to mate with normal mature specimens. Headless chaetognaths must take up nutrients through the integument. It appears that chaetognaths cannot really regenerate head or tail tip.

The spawning of Paracentrotus lividus has been determined on the basis of the annual gonad index cycle at three sites in the Algiers area presenting low, intermediate and strong hydrodynamism. Three biotopes (Posidonia oceanica beds, rocky substrate with photophilous algae and overgrazed rocky substrate) and two depths (1–3 m and 6–10 m) were considered at these sites, the sex-ratio was always strongly in favour of females (2:1 to 3:1). In all sites but one, there were marked differences in the gonad index and the spawning period between sites; the gonad index reached its maximum value at the site with the weakest hydrodynamism, and the minimum value at the site with the strongest hydrodynamism. Spawning took place in April–May and August–September at the site with the weakest hydrodynamism, in April–June and October–December at the site with intermediate hydrodynamism and only in winter at the site with maximum hydrodynamism. The coexistence, on regional scale, of these reproductive cycles might enable Paracentrotus lividus to compensate the mortality during planktonic larval phase by the fact that spawning of this sea urchin occurred in all seasons.

The sea urchin Psammechinus miliaris was sampled at monthly intervals from two replicate sites at contrasting locations (littoral and subtidal habitats) on the west coast of Scotland. Samples were collected from November 1995 to October 1997. A study of gonad development showed a clearly defined annual cycle of gametogenesis with a single spawning period. Gonad indices (GIs) varied between locations, between sites at the same location and between study years. Gonad indices were maximal prior to the onset of the spawning period in June and July. Ripe gametes were shed by dissected urchins from June to September in 1996 and June to August in 1997 coinciding with the time of year when the gonad colour was best in terms of what is desired in the market place. Over winter the GIs were very low and gonads became very dark in colour. Higher summer GIs in the urchins from one littoral site suggested that the urchins there had a seasonal influx of a more nutritious or more abundant food resource. Histological determination of the reproductive state showed that for these food-limited populations high GIs do equate with the spawning period. The gametogenic cycle fits the six stage pattern described for other echinoid species. In females oocytes of various developmental stages were present throughout the annual cycle. Recruitment to the littoral location was monitored over two seasons by quantifying the number of urchins with a test diameter <5 mm appearing in the population. Recruitment appeared variable between sites and between seasons suggesting that the collection of juveniles resulting from natural settlement may not be a reliable alternative to hatchery produced spat. Although P. miliaris has commercial potential when in cultivation, this study provided no evidence of an opportunity for a commercial fishery.

Each spring, a localized stock of herring (Clupea harengus, Teleostei, Clupeidae) spawn in the Blackwater Estuary (Essex, UK). The eggs are laid on a gravel bank (Eagle Bank) at the mouth of the estuary. Incubation takes three to four weeks and, after hatching, the larvae can be caught in the area for several months. In this paper, results are presented from a finite-element circulation model used to simulate tidal and wind driven flow fields for the region. A particle tracking model was then used to simulate the dispersal of young herring larvae, up to first feeding, hatching from the Eagle Bank. The simulations predicted that, over a period of 12 d, around 63% of particles would be retained in the area of the Eagle Bank at high water whilst 22% of particles would be further south towards the Buxey Sands. Over the same time, ∼7% of the particles released would be found in the River Blackwater itself. Imposing a steady state wind of 10 m s−1 from the south-west (the dominant wind direction during spring in this area) or north-east had the effect of moving the majority of particles into the river or offshore to the south respectively.

A molecular genetic analysis of Coris julis from different sites in the Mediterranean and the Atlantic and C. atlantica from the Cabo Verde Islands was applied to infer phylogenetic relationships between the taxa. More precisely, partial 12S mitochondrial rDNA sequence data were used in maximum parsimony, neighbour-joining, and maximum likelihood analysis to generate phylogenetic trees. The polymorphism observed indicated an important differentiation between the C. atlantica and C. julis specimens and supported the existence of two different species.

The hyoid arch and branchiostegal rays of Paraliparis leptochirus (Pisces: Liparidae) and of Paraliparis murieli are described for the first time. The restoration of the validity of Eutelichthys Tortonese on the basis of the presence of only five branchiostegal rays in P. leptochirus, its type species, is proposed. Paraliparis murieli has, as the other Paraliparis spp., a hyoid arch with six branchiostegal rays. The endochondral pectoral girdle of P. leptochirus, P. murieli and P. hystrix is described for the first time, and some data about the girdle of P. edwardsi are given. Differences between P. hystrix and P. murieli, described simultaneously, and between P. murieli and P. australis are established.