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.

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.

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.

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.

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.

In this article four species of Desmodoridae, Desmodora alberti sp. nov., Desmodora marci sp. nov., Desmodorella balteata sp. nov. and Desmodorella spineacaudata sp. nov. (Nematoda: Desmodoridae), are described from hydrothermal vents of the Pacific. The genus Desmodora is revised and lists of valid species are provided; four subgenera are reinstated as genera; Xenodesmodora is regarded as genus inquirendum. Definitions of some morphological structures are given.

The rDNA repeat-unit of the vent polychaete Alvinella pompejana was investigated using restriction analysis. Mapping revealed evidence of rDNA polymorphism within and between individuals which was due to individual restriction site variation and sequence rearrangements involving spacer regions. The size of the repeat unit was 10.5 kb with virtually no evidence of length variation. Sequence inversions indicated the presence of two spatially-distinct subfamilies of repeats, probably on different chromosome pairs. Animals from contrasting vent habitats with respect to age and chemical emissions (young vs old chimneys and white vs black smokers) from within the 13°N/EPR (East Pacific Rise) vent sector were analysed for evidence of population differentiation. Based on individual restriction site variation, average FST estimates across neighbouring populations were in the region of ~0.05 and differed significantly from zero. This level of genetic differentiation is comparable to values reported previously for allozymes. Spatial and temporal allelic frequency variances estimated from pairwise combinations (i.e. s2S and s2T) strongly suggested that differences in allelic frequency were the result of repeated extinction/recolonization events associated with the vent instability. Estimates of the effective population size derived from standardized temporal allelic frequency variances Fks were very low compared to actual population size indicating great temporal fluctuations in the former. Theoretically, such an effective population size is not sufficient to maintain the observed level of polymorphism within the 13N/EPR vent sector. Results are therefore consistent with a ‘propagule’ colonization-type model in which extinction/recolonization rates are high. In Alvinella, planktonic larval dispersal appears sufficient to overcome any genetic differentiation resulting from drift, but these findings also indicate that propagules may only be capable of dispersing a few tens of kilometres per generation.

The population dynamics of Nereis diversicolor (Annelida: Polychaeta) was studied at Stiffkey salt-marshes (north Norfolk coast). Monthly sampling from August 1992 to July 1993, on the lower salt marsh gives a mean annual density of 392 ind m−2 and a biomass of 10·26 g m−2 DW. Cohort analysis was made using ‘Bhatta’ software, allowing the growth and production estimations of the four cohorts. The production was 17·91 g m−2, giving a P:B ratio of 1·8. Nereis diversicolor population has only one recruitment in July.

A new genus is established in Eunicidae: Fauchaldius gen. nov., a symbiont of hexactinellid sponges that has only subacicular hooks, with F. cyrtauloni sp. nov. as its type species. Nine new species are described in Eunice: E. hernandezi sp. nov., E. ibarzabalae sp. nov., E. mikeli sp. nov. and E. nonatoi sp. nov. all belonging to the fuscusbidentate group; E. edwinlinkae sp. nov., E. hartmanae sp. nov., E. lanai sp. nov., and E. miurai sp. nov. all belonging to the flavus-tridentate group; and E. donathi sp. nov. that belongs to the fuscus-unidentate group. Further, two new species are described in Marphysa: M. angeli sp. nov. that is grouped with species having only composite falcigers, and M. orensanzi sp. nov. that belongs to the group with composite falcigers and composite spinigers. A key to identify genera in Eunicidae is included. A key to identify species of Eunice is appended.

It is generally believed that lecithotrophic larvae of annelids do not possess functional excretory organs. However, as in certain annelids the planktotrophic trochophora larva has been secondarily modified into a lecithotrophic developmental stage and because protonephridia are characteristic for the trochophora, lecithotrophic developmental stages should also possess such organs. To test this assumption hatchlings of the orbiniidan Scoloplos armiger, which develops directly without a free-living larval stage, were investigated ultrastrucrurally. Each hatchling possesses a pair of protonephridia which lie caudal to the eyes and almost level with the frontal margin of the foregut. Each organ consists of three multiciliated cells, a terminal cell, a duct cell and a nephropore cell. The terminal cell bears a distally oriented hollow cytoplasmic cylinder, which surrounds the cilia. Adherens junctions connect this structure to the duct cell. Several clefts and pores perforate the wall of the hollow cylinder. Extracellular material covers the pores and clefts and thus may function as a molecular sieve during filtration. A comparison with the protonephridia of other annelid larvae reveals: (1) that one pair of protonephridial head kidneys consisting of a terminal cell, a duct cell and a nephropore cell must be assumed for the trochophore in the ground pattern of annelids and (2) that these organs are preserved when lecithotrophic larval stages evolved within the Annelida

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.

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.

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.

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.

Most fertile individuals of the apodid sea cucumber Polycheira rufescens, living in the intertidal zone near Iso Marine Station in southern Kyushu, Japan, spawned on day one and two before every full and new moon in the period from the second half of July until August or October from 1983 to 1989, the month differing in different years. Synchronous spawning associated with the same phases of the moon was also observed at Sakurajima Marine Station near Iso in 1991. Individuals ready to spawn were divided into four sexual types: two sorts of hermaphroditic males with small or larger growing oocytes and males and females. Further investigation revealed that some individuals changed from male to female or from female back to male in the two week interval between spawnings. Moreover synchronous gametogenesis occurred in association with sex changes throughout the breeding season, the period from initiation of spermatogonia proliferation to spermatozoa release was three weeks, and the period from initiation of oocyte growth to egg shedding was about five weeks.

Allozymes and restriction fragment length polymorphisms (RFLP's) in genes of the NADH dehydrogenase complex (ND 5/6 genes) of mitochondrial DNA (mtDNA) were used to investigate the spatial genetic structure of Atlanto-Scandian herring (Clupea harengus). Samples (sample size=46–50/site) comprised Icelandic summer spawners, Norwegian spring spawners, and two fjord populations, Balsfjord and Trondheimsfjord, on the Norwegian coast. Fifty enzymes were assayed, and samples were routinely examined at 18 enzymes comprising 28 putative allozyme loci. Significant genetic differentiation (P < 0.001) was detected between Trondheimsfjord herring and all other samples, with apparent genetic homogeneity among remaining samples, including the Balsfjord; a region shown previously to contain an allozymically distinct population. Herring from the Balsfjord were shown allozymically to represent the Norwegian spring spawning group, suggesting the presence of two stocks, a deeper resident spawning (Balsfjord) and a shallower, non-native feeding population (Norwegian spring spawning). Variation at the ND5/6 genes using six restriction enzymes revealed 96 composite haplotypes in 196 fish. Mean haplotype diversity was high (0.92), though nucleotide divergence between samples was small (highest=0.00029, between Trondheimsfjord and Balsfjord samples; lowest=0.00003, between Icelandic summer and Balsfjord samples). Monte-Carlo %2 analysis of haplotype frequencies revealed no significant geographic heterogeneity among samples, thus revealing a discordant pattern of genetic differentiation produced by allozymes and mtDNA markers. The detection of a genetically divergent population in deeper waters of the Trondheimsfjord supports the existence of distinct deep-water resident populations in the Norwegian fjords.

We examined recent arguments that leptocephali of the European eel, Anguilla anguilla, swim in an oriented manner, rather than drift, to reach the continental shelf of Europe and the Mediterranean Sea. There is a cline of increasing body length of leptocephali from south to north and from west to east from the Mid-Atlantic Ridge (30°W) to the continental shelf, which could represent migration from south-west to north-east, transport eastward at all latitudes, or increased growth rate with latitude. Evidence that this cline is a trend in age of arriving glass eels along the European coast, and that the duration of migration is less than one year, is weak. Ages reported in the literature for specimens from Morocco to The Netherlands were based on the unvalidated assumption that rings in otoliths were deposited daily. The assumption is unwarranted because of low metabolic rate and uncertainty of nutritional mode of leptocephali. If the assumption were accepted, calculated hatching dates of eels arriving at the European coast imply year-round spawning. Lengths of leptocephali in the Sargasso Sea at various times imply that eels spawn only in late winter and spring. Leptocephali contain tiny amounts of muscle, especially aerobic muscle for sustained swimming. They probably have insufficient capability to swim across the Atlantic in the less than 1–2 y reported by others.

An unusual mass settlement event of the grouper Epinephelus merra occurred on the fringing coral reefs of Reunion Island (south-western Indian Ocean) in April 1994. This major event coincided with stormy conditions associated with the new moon period. The abundance of new settlers was surveyed for 45 days following settlement on both the reef flat and the back reef area of the coral reefs of St Gilles, La Saline and St Leu. Mean densities of settlers were higher on reef flats (maximum 474 ind/20 m2 at La Saline) than on back reef areas (maximum 156 ind/20 m2 at La Saline). Seven weeks later, densities of settled E. merra had drastically decreased, and did not differ with site and zone (18.5 ind/20 m2). Percentages of post-settlement mortality at that period ranged from 85 to 88% in back reef areas and from 93 to 95% on reef flats. A strong correlation between density of recruits and per capita mortality suggests density-dependent early post-settlement mortality for E. merra. The limitation of food resources and shelters, perhaps combined with an increase of diseases due to high population densities of settlers, was probably the main cause of mortality just after the mass settlement. Predation by reef fish, including cannibalism between settlers, is probably responsible for most subsequent mortality.

The fish Hoplostethus mediterraneus is a bycatch of the deep-water trawling in the north-western Ionian Sea. Data on its life history traits were collected during twelve trawl surveys carried out at two month intervals, between August 1993 and July 1995.

A vertical distribution according to size was observed for this species. The year's young were recruited mainly during the spring-summer period. Sex-ratio changed by size with females larger than males. Mature specimens were found mainly between May and November with a reproductive peak during late summer.

Seasonal growth was detected in the otoliths; the maximum ages of 11 and 10 y were observed in females and males respectively. Von Bertalanffy growth parameters for the whole population were: L3C=287–08 mm, k=0–127 y, to=-2–131. No significant differences were detected between the growth patterns of the sexes. Overall growth perfomance depicted through size-distribution analysis was not significantly different from that obtained by otolith reading.

Estimates of natural mortality rate for the whole population ranged from 0–14 to 0–20. Population structure, growth pattern, age at first maturity and low natural mortality rate indicate a life history mainly constituted by k-strategy characters and regulated by density-dependent mechanisms.