A new deep-water Actiniaria species, Isanthus homolophilus sp. nov. is described from the French Polynesia. Morphological and ecological differences between the new species and the other known species of the genus Isanthus are discussed. The distinct morphological characteristics that distinguish I. homolophilus, are the presence of a tentaculated columnar margin, the tentacle number (84–96), and its cnida biometry. A further ecological characteristic is the distinct symbiotic relationship that the anemone exhibits towards the decapod Hypsophiys inflata.

During the biological researches of the ‘Service Mixte de Contrôle Biologique’ (SMCB) in French Polynesia (1986–1990) at depths ranging from 100 to 1120 m, a symbiotic association between a deep-water homolid crab, Hypsophrys inflata Guinot & Richer de Forges, 1981 and a sea anemone of the genus Isanthus (Actiniaria: Isanthidae) was collected. Even though this association was described by Guinot et al. (1995) and Chintiroglou et al. (1996), no concise description of the anemone is given. Thus, the goal of the present study was to provide a detailed description of the new anemone species and compare it with other species of the Isanthidae Carlgren, 1938 family.

The methodology followed in our investigation was that of Doumenc & Foubert (1984) and Doumenc et al. (1985). Nematocyst nomenclature used was as proposed by England (1991). Abbreviations: MNHN (Museum National d'Histoire Naturelle Paris).

One hundred and ninety-eight suprabenthic hauls from the English Channel and the Seine Estuary were taken with a modified Macer-GIROQ sledge. Numerically, mysids were the dominant group amongst the peracarids collected with the sledge and 28 species were recorded. Mysid densities were higher in the oligohaline zone (>200,000 ind 100 m-3) of the Seine Estuary than at other stations in the English Channel (where the density was the highest on medium sand stations, ~5000 ind 100 m-3). Two main gradients of mysid distribution were identified: (1) a higher species richness in the western part of the Channel compared with the eastern part of the Channel; and (2) an increasing density gradient from west to east during spring and a decreasing gradient from west to east during the autumn (eastern high abundance of Haplostylus spp. during spring, and western high abundance of Schistomysis ornata and Erythrops elegans during autumn). Mysids showed important diel rhythms with maximum abundance at sunrise and sunset, and low density at night. According to their swimming activities, suprabenthic mysids were classified into three groups: upper organisms with a very strong activity, species with a strong activity and occupying the whole water column near the sea-floor, and lower species with limited swimming activity. Nevertheless, the swimming activity could be modified according to the hydrodynamics of each site. A seasonal cycle of abundance (summer recruitment for dominant species Anchialina agilis, Haplostylus lobatus, Haplostylus normani) was observed on two stations where temporal samples along the year were available.

The reproductive biology of the gregarious Mediterranean vermetid gastropod Dendropoma petraeum (Mollusca: Gastropoda) has been studied in the south-eastern coast of Spain. It apparently is a gonochorisric species with the sex ratio biased toward females (71%). A broad peak of more intense reproductive activity occurs in spring months and an inactive reproductive period during winter. The gonad of the males develops about two months before those of females, and storage of sperm by females has been observed. Internal fertilization takes place after the capture of pelagic spermatophores.

The egg capsules lie free within the female mantle cavity, and females brood up to 86 capsules simultaneously (the highest number reported for any vermetid gastropod). The size of the capsules is somewhat variable and increases slightly from those containing first stages of development (mean = 678×579 μm) to those containing late stages (mean = 996×693 μm). Each egg capsule usually contains a single large egg or embryo, but sometimes two (8.2% of the capsules) or rarely three (0.24%). Production of egg capsules by females seems to be continuous throughout the reproductive period (from March to October).

The unsegmented eggs measure from 440 to 507 μm in diameter (mean = 482) and are the largest reported for any vermetid gastropod. Nurse eggs are not present, and therefore most of the intracapsular nutrition comes from the internal yolk of the embryo.

Development is lecithotrophic without a pelagic larval phase. The late intracapsular veliger stage metamorphoses within the capsule and hatching occurs at a crawling juvenile stage.

Detailed catch and life history data for Perioculodes longimanus and Pontocrates arcticus, together with more limited comparable information on Synchelidium maculatum, are reported. Samples were taken year-round using a 0–5 mm mesh D-net towed over sand in the immediate sublittoral zone (-2 to -6 m Chart Datum) in Kames Bay, Great Cumbrae Island, Scotland. Estimated population densities of Perioculodes longimanus were highest in summer. The occurrence of Pontocrates arcticus was more erratic and S. maculatum occurred only in midsummer in very low numbers. The mean sizes of all population categories of Perioculodes longimanus were bigger in summer than in late autumn and winter. Female Perioculodes longimanus parasitized with the copepod Sphaeronella minuta were significantly smaller than the whole category ‘sexable females’. Adult female S. minuta (one per amphipod brood pouch infected) carried — 70–200 eggs per sac. In both Perioculodes longimanus and Pontocrates arcticus females were larger than males. In Synchelidium maculatum, by contrast, males and females were not different in size. Gravid females were present virtually year-round in Perioculodes longimanus and Pontocrates arcticus, with particularly high proportions of ovigerous females in midsummer and low proportions in midwinter. Both of these species had an annual life cycle with only one generation per year. Longevity was estimated at 15 months. The sex ratio nearly always showed substantial female dominance in all three species. Fecundity appeared to be related to body size but, due to egg losses during sample processing, data were too few for detailed analysis. The eggs of Perioculodes longimanus and Pontocrates arcticus were elliptical in shape, with winter eggs being smaller than summer eggs in Perioculodes longimanus, but larger in Pontocrates arcticus. The percentage of ovigerous females in the population was significantly correlated with a range of environmental factors tested, the highest correlation being with maximum weekly air temperature (for Perioculodes longimanus) and daylength (Pontocrates arcticus), although causative effects cannot be established since temperature/daylength factors were not independent variables

A new species of Aoridae, Camacho faroensis is described and figured from Faroese waters and a new species of Isaeidae, Megamphopus raptor, is described and figured from Icelandic waters. The female of Chevreuxius grandimanus is described for the first time as is the hyperadult male of Autonoe borealis.

Results are presented of a comparative study on seasonal variations in population density, population structure and reproductive bionomics of two species of offshore benthic oedicerotid amphipod, Westwoodilla caecula (from 35 m depth) and Monoculodes packardi (from 190 m) in Loch Fyne (Scotland). Observations on live coloration and behaviour of these species in laboratory aquaria are also included. Male W. caecula were, on average, smaller than females. In M. packardi (atypically among Oedicerotidae) the reverse was true. Population densities of both species, calculated from sledge net tows (1-mm mesh), fluctuated erratically over one year (1992). Ovigerous W, caecula were recorded virtually year-round, but were commonest from midsummer to early autumn. Ovigerous M. packardi were noted in spring and early autumn. Monoculodes packardi had a semi-annual life cycle, but the pattern for W. caecula was less clear. The two generations of M. packardi grew at broadly similar rates, presumably associated with the damped seasonal fluctuations in physical environmental factors at 190 m. Female W. caecula possibly moult eight or nine times, and may produce three successive broods in a lifetime (M. packardi may only produce two). A positive correlation was found between fecundity (stage I eggs) and body length in W. caecula but, although a similar trend was apparent in the data for M. packardi, relevant data were too few for significance to be achieved. Ovoid eggs increased in volume by ×2 from stage I-IV in W. caecula, or ×1·5 from stage I–III in M. packardi. Brood sizes were much smaller in W. caecula than in M. packardi, although apparent brood mortality was higher in the latter. There was no significant relationship between the proportion of ovigerous females in the populations of either species and seasonal variation in physical environmental factors considered (temperature, salinity, daylength).

In order to establish the suitability of oyster bags as a method for Manila clam culture, Ruditapes philippinarum (Mollusca: Bivalvia), five batches of clams (mean live weight 0·55 g) were placed on the ground in the intertidal zone of Eo Estuary in March 1993. Four batches were sown in bags at different densities (100, 250, 500 and 1000 clams per bag) and one sown at 160 clams per m2 in sand–gravel bed covered with plastic netting.

In August 1993 and April 1994 all batches were picked up and survival, live weight, length, height and thickness recorded. Survival of clams at the highest density was significantly lower than survival at lower densities in August 1993 (60·5%) and April 1994 (26·7%), but no differences were found among the other treatments. In addition, we found differences in growth between sets in both dates, with the best growth in the lower densities and reduced, density-dependent growth in the bags. Biometric relationships were also affected by density at the end of the experiment. High density had a greater influence on reducing shell height than on length or thickness.

It was concluded that traditional ground culture in Europe is, from both the biological and the economical viewpoints, more efficient than oyster bag culture. However, oyster bags may be useful for temporary storage or as nursery system for clams.

The cirral activity of the whale barnacle Cryptolepas rhachianechi was studied in a flow tank at different flow regimes. In still water, unidirectional flow, and oscillating flow, the cirral fans of adult animals always beat in the direction of the rostrum. Adults did not respond to water current from the carinal direction by facing the cirral fan into the current; however, during copulation they could turn the cirral fan so it faces the carina. Newly settled animals responded to flow from the carinal direction and to oscillating flow by facing their cirral fans towards the oncoming current, but there is no synchronization between changes in water flow direction and the change in cirral direction. Since these barnacles are normally exposed only to unidirectional currents, with no need to respond to flow from the carinal direction or to oscillating flow, it seems likely that they have lost the ability to change the direction of their cirral beats. This loss of the ability to respond to changes in current direction is a specialization of C. rhachianechi related to its epizoic mode of life.

The distribution of Lepeophtheirus salmonis larvae in Killary Harbour was investigated by taking plankton tows from a number of stations on a regular basis during the spring/summer period in 1995 and 1996. Current patterns, ovigerous lice loads on the resident fish and water temperature and salinity were also recorded during the study. Larvae were only found consistently at a station close to a salmon farm at the mouth of the harbour. In the inner harbour, close to the mouths of two rivers, larvae were recovered in sporadic time blocks. Highest densities of larvae were found at the beginning of the study in both years in the inner harbour with a subsequent decrease in the following months. The distribution, density and origin of the larvae are discussed in relation to the prevailing current patterns in the harbour, the ovigerous lice loads on the resident fish and the requirements of the larvae to locate a new host and complete the life cycle.

Eriocheir sinensis, the Chinese mitten crab, is a native of east Asia and predominantly lives in freshwater but migrates seawards to breed. In 1912 a specimen was collected in the River Aller, a tributary of the Weser, Germany and now this exotic species has a European distribution from Finland to the Atlantic coast of southern France. In the UK, the mitten crab has been reported from the Humber, Medway and Thames catchments. Although the population in Thames had remained low, recent evidence suggests it is increasing, which has potential environmental implications.

The occurrence in British coastal waters of the swimming crab Liocarcinus vernalis is confirmed for the first time. Features are given to enable this species to be distinguished from the closely related L. holsatus and L. marmoreus. The zoogeographical distribution and bionomics of L. vernalis are briefly discussed.

A total of 57 comparative hauls using a rectangular midwater trawl with a fishing mouth area of 50 m2 (RMT 50) were carried out along the sides of an imaginary triangle south of Madeira in 1986. A total of 1258 cephalopods were caught, giving a mean of 22 per haul with a range from 0 to 67. The nets were used with a diver's light on the top bar which was either switched off or was operated with a 20, 70 or 150 W bulb, powered by a car battery. A significantly greater number of individuals per haul was caught with lights on than without lights, increasing from a mean of 13·5–25·1, a factor of 1·8. Similarly, the number of species caught was increased from a mean of 7 to 10·4, a factor of 1·5 and the volume of cephalopods was increased from a mean of 41·1–162·3ml, a factor of 3·9. Similar comparisons made for catches during day or night separately and on the three courses separately also showed marked increases with the lights. Samples show that increase in power of the lights increased the total number of cephalopod individuals caught. In the 12 species with more than ten individuals, in 33 of the 36 comparisons (of number of individuals, species and volumes) there is an increase with the light. The most influenced species was Taonius pavo which increased in numbers by a mean factor of 3·9 times with 20W, 4·0 times with 70W and 6·1 times with 150W when compared with the numbers caught with no light.

Allozymes of Paracentrotus lividus from Palermo Gulf in the northern Sicilian coast (Italy) and from a small body-size population in the western Greek coast (Ionian Sea) were investigated by PAGE. Five of the twenty examined loci were polymorphic (AAT*, ADH*, ME*, PGI* and PGM*) over each population with a polymorphism value of 0–25. Average heterozygosity was equal to 0081 in the Sicilian sample and 0084 in the Greek. Deviations from Hardy-Weinberg equilibrium were significant in ME* and PGI* loci (as calculated by y). Nei's (1978) genetic distance (D=0–0025) index described a close identity between the two samples. F ST value of polymorphic loci ranged from 0001 to 0029, its mean value (0–008) resulting low and appearing to be discriminate between the samples with a significant difference (P<0–05). The number of migrants per generation was equal to 31.

During the Joint Chilean–German–Italian Magellan ‘Victor Hensen’ Campaign in 1994 an epibenthic sledge (EBS) was used to catch the epibenthic and benthic-boundary-layer macrofauna.

Eighteen EBS samples were taken at 12 locations on a transect through the Beagle Channel. The aims of the study were to describe the epibenthic molluscan species, to quantify their abundances and to describe their distribution. In total 35,087 specimens were collected, yielding 107,223 ind 1000 nr−2. Bivalvia were most abundant 78,615 individuals (52 spp.) followed by Gastropoda (17,289, 52spp.), Aplacophora (4745, 9 spp.), Polyplacophora (4665) and Scaphopoda (1909,5 spp.). The molluscan abundance of the hauls were strikingly different, between 3 and 37,927 ind 1000 m−2 haul. Only stations off the eastern entrance showed high abundances, which was represented at all depths and sediments. Elsewhere the abundances were low. Species richness was highest in shallow water (< 100 m) with 69 species and decreased with depth. But at the deepest station 37 species were found.

The prosobranch limpet Patella vulgata is an intertidal grazer performing looped excursions centred on a home scar. Foraging within each excursion is mostly concentrated around the point of maximum distance from home. The orientation of the foraging excursions in a group of limpets was analysed on a vertical substrate on a sheltered shore in North Wales. The spatial relationship between different excursions of the same individual was also analysed. A total of 174 complete excursions from 47 adult limpets were obtained using the LED (light emitting diode) tracking technique. In particular, the leaving direction and the direction of the main foraging area of each excursion were computed. When considering the foraging strategy over five consecutive days, a substantially radial cropping pattern was evident at both the population and individual level, with no evident directional preference. However, when considering consecutive excursions of the same individual a concordance in leaving directions was evident in about 40% of cases. The high overlap between the outward branch of the trajectory of one night and the homing branch of the previous one suggests that the directional decision can be based on a trail-following mechanism. Moreover, our data suggest that directional decisions are taken at the beginning of each excursion when leaving home.

Growth in Loliolus noctiluca (Myopsida: Loliginidae) in Western Port, Victoria, Australia was studied from statolith growth increments. Tetracycline staining experiments verified previous work on tropical forms of this species that showed growth increments to be deposited daily. A logistic growth function described the relationship between length and increment number. There appear to be major differences in the form of growth, longevity and life history pattern between tropical and temperate forms of this species. These are probably attributable to differences in environmental conditions.

In vitro short time experiments (a few weeks) show that daily ingestion by Pamcentrotus lividus (Echinodermata: Echinoidea) is weak (0–81 mg DW d-1 ind-1) for Caulerpa taxifolia (Chlorophyta), compared to the data recorded with an almost totally avoided brown alga, Cystoseira compressa (24–137 mg DW d-1 ind-1) and with a preferred brown alga, Halopteris scoparia (79–397 mg DW d-1 ind-1). There is no significant difference between spring (when the toxic metabolite content is at its minimum) and summer-autumn (when it is at its maximum). In contrast, the absorption rate of the sea urchin fed on Caulerpa taxifolia is significantly weaker in spring than in summer-autumn. Overall, the daily absorbed weight is negative in spring with C. taxifolia (compared with 18 mg DW d-1 ind-1 with Cystoseira compressa and 25 mg DW d-1 ind-1 with H. scoparia). It has also been demonstrated that P. lividus becomes accustomed to Caulerpa taxifolia, at least for short time experiments: the echinoid consumes greater quantities of this alga especially if it is fresh when it has already consumed it previously.

Lagoonal mud snails have been shown to suffer approximately 50% mortality between hatching and adulthood. Experiments were conducted in the laboratory to assess the role of predators on the survival of juvenile Hydrobia neglecta (Mollusca: Gastropoda). Adult snails were collected from a lagoon in the Reedland Marshes system at Dunwich, Suffolk, and their eggs hatched in the laboratory, providing a population of juvenile snails which could be presented as a food source. The vessels, kept at environmental regimes close to that of the natural environment, were seeded with juvenile snails at field density. Predator preference was established by exposing the juvenile snails to combinations of potential predators found in the lagoon. One experiment also gave predators a choice of various juvenile snail sizes and other prey species. Juvenile snails remaining alive after the four week exposure to predators were removed, counted and measured. In the absence of other prey, the opisthobranch snail Retusa obtusa preferentially consumed 50% of the available juvenile H. neglecta over a four week period and the nemertean Lineus ruber up to 90%, making them the major contributors to juvenile H. neglecta mortality. The infaunal anemone Nematostella vectensis, did not have a significant impact on snail survival in the experiments but was observed (incidentally) in a separate non-experimental situation engulfing juvenile H. neglecta. The stickleback Gasterosteus aculeatus and the lagoonal prawn Palaemonetes varians, did not contribute directly to the observed mortality of juvenile mud snails, but were found to consume other predators, producing a system of prey preferences in the food chain. Understanding the role of predation contributes to the understanding of ecological processes occurring in rare lagoonal systems.

The reproductive cycle of Nassarius (Hinia) reticulatus was investigated in the Ria de Aveiro on the north-west Portuguese coast during 1992 and 1993. A clear seasonal pattern was observed with the beginning of gametogenesis in August followed by ripening of the gonads in January and February and spawning from February to July. The increase of water temperature above 11°C in February 1993 was associated presumably with the release of gametes. Recruitment inside the Ria of juveniles with 6·5 mm mean shell height was detected in February 1993 and these individuals were spawned in the previous year. Males of N. reticulatus exhibited a considerable variation in length of the penis throughout the reproductive cycle. The accuracy of the use of relative penis length (RPL) index for intersite comparisons of imposex is discussed and the magnitude of the error that might be involved when comparisons are made using populations in different phases of the reproductive cycle is evaluated.

The scorpaenid Maxillicosta scabriceps (Teleostei) and the platycephalid Platycephalus longispinis (Teleostei) were trawled seasonally for a year from shallow (5–15 m) and deeper (20–35 m) waters in four distantly-located regions of the inner continental shelf of south-western Australia. The former species was more abundant in southern regions, which is consistent with its temperate distribution, while the latter species was more abundant in deep than shallow waters. Unlike M. scabriceps, P. longispinis with total lengths < 110 mm were rarely caught, indicating that this latter species only moves on to the sandy substrate of the inner shelf when it reaches a certain size. As M. scabriceps increased in size, the contributions of mysids, amphipods and oxyrhyncan crabs to the diet declined, while those of carid decapods and brachyrhyncan crabs increased. The invertebrate fauna ingested by the smallest length-class of P. longispinis, 110–139 mm, was similar to that of the same and largest length-class of M. scabriceps. However, unlike M. scabriceps, this length-class of P. longispinis consumed teleosts, despite having a relatively smaller mouth. The contribution of teleosts subsequently increased as P. longispinis increased in size, a feature reflected by the relatively low dietary breadth of large fish. The marked shift in the types of prey ingested by P. longispinis as it increased in size accounted for the fact that, in contrast to M. scabriceps, there was limited dietary overlap between the larger and smaller members of this platycephalid. The ability of P. longispinis to ingest other fish is presumably related to the fact that platycephalids lie just under the substrate surface and are thus concealed from their potential prey, and that they are able to emerge rapidly and pursue their prey.