A seasonal survey was undertaken, over a year, of phytoplankton from surface water in the western English Channel (Station L4) measuring mycosporine-like amino acids (MAAs), photosynthetic pigments and microscopic counts. Ground level solar radiation (ultraviolet-B, ultraviolet-A and photosynthetically active radiation; UV-B, UV-A and PAR) was measured at a nearby site. From this we estimated in situ solar irradiance received by phytoplankton using measurements of the mixed layer depth and calculations of the 50% light level cut-off. The MAAs occurred year round, with concentrations increasing rapidly during spring and summer (maximum 8·5 μg l−1) to levels exceeding those of chlorophyll-a (chl-a maximum 3·6 μg l−1). On two occasions, increases in specific MAAs coincide with algal blooms. In spring, increases in mycosporine-glycine (λmax 310 nm in the UV-B) coincide with a bloom of the prymnesiophyte Phaeocystis pouchetii and in July and August increases in an unidentified MAA (λmax 328 nm) match a bloom of the diatom, Guinardia striata (=Rhizosolenia stolterfothii). Concentration of MAAs, but not chlorophyll, correlate with in situ irradiance. The ratio of MAA to chl-a increases linearily with in situ irradiance received by phytoplankton reaching 13·9 nmol MAA (nmol chl-a)−1 at 101 W m−2. Evidence of photoinduction is observed during the P. pouchetii bloom with a four fold increase in the concentration of mycosporine-glycine (maximum 2 pg cell−1) as UV-B:PAR ratio increases from 0·0011 to 0·0014. Dinoflagellates, although contributing to <10% of biomass, are found through the correlation of MAAs to the biomarker peridinin, to contribute to baseline levels of MAAs throughout the year. Our MAA:chl-a values for the English Channel are similar to those measured in coastal areas of southern USA. Similarities with studies on Antarctic phytoplankton are also found with the dominance of porphra-334 and the presence of mycosporine-glycine in P. pouchetti.

A radical change in the abundance of invertebrate megafauna has occurred over a vast area of the Porcupine Abyssal Plain, north-east Atlantic, in recent years. In particular, the holothurian Amperima rosea has increased in abundance by three orders of magnitude. The sudden increase in abundance of A. rosea appears to be the result of environmental forcing rather than localized stochastic population variations. Amperima rosea produces small eggs ([les ]200 μm) indicating (1) planktotrophic larval development or (2) lecithotrophic larval development with an abbreviated larval stage. It also reaches maturity at a very small size. The reproductive biology of A. rosea indicates that it can increase rapidly in population size and can colonize large areas quickly. It has high fecundity, as predicted by gonad indices and observed in histological studies. Fecundity was greater in winter than in summer months, but there was no clear evidence of seasonal or episodic reproductive events. All males, irrespective of sample season or year, were mature with spermatozoa. Most oocytes were of an intermediate size (70 to 120 μm), either at the late previtellogenic (70–90 μm) or early vitellogenic (100–120 μm) stage of development. It is postulated that development of full vitellogenesis, leading to episodic spawning, might be dependent on certain environmental stimuli. The most likely stimulus is food supply. Amperima rosea has been shown to feed preferentially on phytodetritus and to have a requirement for certain sterols in its diet. Qualitative changes in the flux of organic matter to the sea-floor may control vitellogenesis and fecundity, and hence have an effect on the population dynamics of the species.

Data came from the Irving, Meteor and Plato seamounts and, were obtained during the Seamount 2 Expedition on board the RV ‘Le Suroît’ in 1993. On the three seamounts, polychaetes were sampled at 44 sites from 260 to 1800 m: 8 sites on Irving, 27 on Meteor and 9 on Plato. In all five seamounts, 1753 individuals were collected: 403 on Atlantis, 346 on Hyeres, 523 on Irving, 387 on Meteor and 94 on Plato. The species richness from the five seamounts is 53: 31 on Atlantis, 24 on Hyeres, 20 on Irving, 28 on Meteor and 21 species on Plato. Only nine species are present on all five seamounts. Three families Onuphidae, Amphinomidae and Eunicidae are dominant. Two groups of seamounts were identified by cluster analysis: Atlantis and Hyeres and, Irving, Meteor and, Plato. The distribution of the polychaetes collected on these five seamounts are compared with the polychaete fauna from the North Atlantic ocean.

Ontogenic change patterns in otolith Sr:Ca ratios in the threespine stickleback, Gasterosteus aculeatus, collected from Japanese brackish waters and freshwater, were examined by wavelength dispersive X-ray spectrometry on an electron microprobe. Two-dimensional images of the Sr concentration in the otoliths showed a variety of patterns of Sr concentration relative to salinity of habitat in all specimens collected in Hokkaido Island. Otolith Sr:Ca ratios in line analysis of all specimens collected in Hokkaido Island fluctuated strongly during the life history transect in accordance with the migration (habitat) pattern from sea to freshwater, via brackish water. In contrast, the Sr concentration or the Sr:Ca ratios of the Otsuchi River stickleback remained at consistently low levels throughout the otolith (1·5×10−3 in the Sr:Ca ratios). The higher ratios (3·2–6·3×10−3) in sticklebacks collected in Hokkaido Island probably reflect the ambient salinity or the seawater–freshwater gradient in Sr concentration. The findings clearly indicated that otolith Sr:Ca ratios reflected individual life histories, and that the stickleback had a flexible migration strategy in the ambient water.

The nauplii of Balanus amphitrite (Cirripedia: Thoracica) were cultured on a daily diet of Chaetoceros gracilis at different concentrations. Both young (zero-day old) and aged (six-day old) cyprids were subject to attachment assays, followed by studies of juvenile growth and survival for two weeks under laboratory conditions. The TAG/DNA ratio of cyprid increased in the following order of food concentrations: 106>105>104 cells ml−1. More than 70% of cyprids metamorphosed in the presence of conspecific settlement factor, irrespective of their TAG/DNA ratio. The juvenile growth and survival in young cyprids surpassed that of the aged cyprids. The TAG/DNA ratio had no significant effect on juvenile growth and survival in both young and aged cyprids. The negative effect of delayed metamorphosis on juvenile growth and survival appeared to be independent of the TAG/DNA ratio.

Habitat mimics were used to investigate the role of coralline algal frond length in determining spatial patterns in diverse gastropod assemblages on a rocky shore near Sydney, Australia. Frond length represents the vertical scale component of habitat structure, which is rarely experimentally manipulated. Length of fronds did not explain differences between gastropod assemblages at different tidal heights or among patches of turf separated by tens of metres in mid-shore areas. In contrast, changes in frond length caused large differences in the structure of gastropod assemblages in low-shore areas. Contrary to previous studies, the total abundance and diversity of gastropods was greater in turf with short fronds than with long fronds. Possible mechanisms for this negative relationship are discussed. Overall, the vertical scale component of habitat structure can have strong effects on associated faunal assemblages, but the magnitude of these effects depend heavily on local environmental conditions (e.g. different tidal heights).

Retained catches of trawl fleet in Chalkis fishing port-market, Greece, were analysed using generalized linear models (GLMs) in an attempt to identify factors that influence the total landings of the groundfish fisheries. Main effects in the model included a factor for vessel tonnage that determined fishing power, as well as factors for month and fishing area. Covariates examined were all found to have a significant effect on the retained catches, with month and vessel capacity alone explaining 38% and 30% respectively of the total variation of the data. Significant interactions observed indicate that the fluctuations in retained catch differed by fishing area and month as well as by fishing area and vessel category. Within vessel categories, month and fishing area also had significant effects on the retained catches, with fishing area being more important than month for the smallest vessels. Results indicate that the modelling approach of retained catches from trawl fisheries is a promising method for obtaining representative abundance indices.

Growth of seed mussel Mytilus galloprovincialis (Bivalvia: Mytilidae) from two origins (rocky shore and collector ropes) placed on raft culture was compared. Mussel seed were cultivated following the commercial culture phases commonly used in Galician Rías: (a) from seeding to thinning-out and (b) from thinning-out to harvest. Differences in growth rate were clearly related to the phase of the culture, being significant during the first phase from seeding to thinning out (January–November 1998). In the latter phase, weight values observed for collector rope mussels were significantly higher than those for rocky shore individuals (0·65 vs 0·45 g total dry weight, 0·11 vs 0·08 g tissue dry weight, 0·53 vs 0·37 g shell dry weight and 0·09 vs 0·07 g tissue organic weight per month, respectively; P<0·001). Neither shell length nor weight (soft tissue or shell) growth rate showed differences during the second phase of the culture from thinning out to harvest (November 1998–July 1999; P>0·05). Nevertheless, in terms of output, the higher number of individuals above 70 mm (77% vs 61%) and the heavier soft tissue (and total) weight (23–30%) for collector ropes mussels when compared to rocky shore ones at harvest, highlighted the importance of choosing the former stock. Condition index (CI) did not differ at the onset of the culture between both origins (P>0·05), but mussels from collector ropes showed significantly higher values than those from the rocky shore from May to November 1998 (P<0·001) before thinning-out was undertaken. No differences in CI were observed from thinning out to harvest between both types of mussels (P>0·05). Although both populations showed normal (unimodal) size distributions at the onset of the culture, mussels from rocky shore origin fitted better to bimodal profiles throughout the first phase of the culture. These bimodal distributions of rocky shore population did disappear during the second phase suggesting a more uniform size spectrum as a consequence of the thinning out process, which involves a selection of size.

The chromosome number and karyotype of amphioxus Branchiostoma belcheri tsingtauense were studied using embryonic cells. The diploid chromosome number (2n) of B. belcheri tsingtauense is 36, and its karyotype 2n=36, 2st+34t, FN=36. This is the first report on the karyotype of the cephalochordate. Evidence suggesting the possible presence of a pair of sex-chromosomes in the amphioxus has been provided.

Interannual and seasonal variation in recruitment of serpulid tube worms was monitored at two depths at each of four sites between February 1999 and January 2001 in Bantry Bay, Ireland. In both years, a single peak in recruitment was observed. The timing of the peak was similar in both years, but the magnitude of the peak differed significantly. More individuals recruited onto the underside than on the upperside of the horizontally orientated panels. A higher density of recruits was observed at a depth of 7 m than at 4 m during recruitment maxima. There was little variability in recruitment rates either within or between sites. The proportions of Pomatoceros triqueter and P. lamarckii recruiting per deployment were examined. Juvenile mortality was high. Based on ongrowing laboratory experiments, the dominant species was P. lamarckii. Serpula vermicularis was also present in low abundance. Examination of the spatial patterns of distribution of the serpulids indicated that the recruits were aggregated within panels. The degree of aggregation was correlated with the overall density of recruitment per panel.

The distribution of the warm-water barnacle, Balanus perforatus, was surveyed along the south coast of England and the north-east coast of France between 1993 and 2001, repeating work carried out between the 1940s and 1960s. The species has recovered from catastrophic mortality during the severe winter of 1962–1963 and was found over 120 km (UK) and 190 km (France) east of previous records on both sides of the Channel. The presence of the species in the eastern Channel refutes suggestions in the 1950s that larvae, and hence adults, would not be found east of the Isle of Wight because of reproductive sterility close to the limits of distribution. Brooding of specimens translocated to Bembridge, Isle of Wight, commenced in May, earlier than previously observed in British waters, and continued until September. The stage of embryo development at Bembridge in mid-August was comparable to that of the large population at Lyme Regis, Dorset 100 km further west. However the size of brood per standard body weight was greater at Lyme Regis. Factors influencing the rate of colonization and further geographic range extension of the species as a possible result of climate change, are discussed.

The relation of moisture content, temperature, nest depth, incubation, distance from sea and vegetation to hatching success of loggerhead sea turtles, Caretta caretta, in Turkey was studied. Nineteen randomly selected clutches were examined. Moisture was found to be negatively correlated with distance from the sea (P<0·05) but positively correlated with temperature (P<0·01). Temperature was negatively correlated with incubation time. Hatching success was not correlated with any of the environmental factors examined.

The objectives of this study were to assess population biology and dynamics of the squat lobster Galathea intermedia. On the basis of nearly regular monthly samples taken with a 2-m beam trawl in the Helgoland trench (HTR) during the period of 1985 until 1992, sex ratio, length composition, relative growth and reproduction were studied. The overall sex ratio deviates significantly from 1:1 with 1[male]:1·8[female] (P[les ]0·001). On average, sexes are equally large, but adult females attain a slightly larger size than adult males. No sex-specific differences in the length–weight relationship were found. Relative growth of the first abdominal segment is clearly of sexual-dimorphic character. On the basis of the length–frequency distributions, the life cycle of the HTR population lasts between one and two years. According to the appearance of ovigerous females and juveniles, reproduction and recruitment are clearly seasonal. Recruitment takes place between July and December. The main reproduction begins in April and ends in September, with a peak between June and August. A significant increase of specimens showing both male and female morphological characters, referred to as morphological hermaphrodites (P[les ]0·001), and males (P[les ]0·05) respectively, was detected.

The presence of two dinoflagellate species of the genus Asterodinium, which are a priori representative of warm waters, is reported for the first time in the western Mediterranean Sea. Asterodinium libanum was identified in the Bay of Villefranche-sur-Mer (Ligurian Sea), while Asterodinium gracile is reported in the Tyrrhenian Sea. These findings are discussed in the context of the progressive warming of Mediterranean waters.

The decapodid and first two juvenile stages of the caridean shrimp Campylonotus vagans from the Subantarctic Beagle Channel (Tierra del Fuego, Argentina) are described and illustrated in detail. The complete larval and early juvenile development of this species from rearings under controlled laboratory conditions were analysed. Zoeal morphology in two stages of an abbreviated development was identical to a description from plankton and hatched larvae of a previous work, and therefore we only compare and discuss slight morphological variations in this study. The first juvenile is large and already resembles some features of adults, lacking all ventral rostral and the fourth dorsal rostral spine only which appears in the following stage, and the second pereiopod not yet being as predominant as in adults. Sexual determination is not yet possible up to the described second juvenile stage. The abbreviated larval development in a Subantarctic shrimp species is discussed as an adaptation to low temperatures and pronounced seasonality.

The influence of circulation on abundance patterns of larval fish was compared at different phases of the tide in the vicinity of an estuarine front in Corral Bay, Chile during austral spring. Greatest differences in water salinity were found across the frontal region on ebb tides. Because rainfall was low, density differences were primarily due to tidal intrusion of salt water. Larval density was relatively low during both sampling periods with Strangomera bentincki, Oodntesthes regia laticlavia, Gobiesox marmoratus and Hypsoblennius sordidus as the most abundant species. Total ichthyoplankton was always higher near the tidal front (Stations 2 and 3). Spatial distribution in relation to tidal phase showed different patterns for the most abundant fish larval species. Circulation and larval distribution revealed that the bay was a source of young fish larvae but older individuals could also be recruited in and retained there. Results show that the front could act as a physical boundary for larvae transported from offshore through specific mechanism of circulation related with the tidal regime.

Elaphognathia cornigera is a temporary fish-parasitic isopod crustacean that inhabits intertidal sponges. The life cycle and growth rate of this species were investigated using a laboratory rearing experiment. In addition, a wild population of this gnathiid isopod was sampled at fortnightly intervals over a 2-year period on an intertidal rocky shore at Oura Bay, Izu Peninsula, southern Japan. The population dynamics of this species were assessed using data from the laboratory experiment. Under laboratory conditions, individuals reached maturity after alternating between the parasitic feeding stage and the independent moulting stage three separate times. The mean larval period at 25°C was around 52 days. All life stages were observed in the natural population between spring and autumn. The density curves for all larval stages showed three to four distinct peaks, with the exception of the first larvae just after eclosion. According to the emergence patterns and growth rates derived from the laboratory experiment, E. cornigera appeared to alternate generations three to four times per year. During the winter months, only larvae in the second post-feeding phase and adult males were observed. This may have resulted from a halt in the development of larvae at the second post-feeding stage, triggered by cold winter conditions, and the post-reproductive death of semelparous females. Overwintered larvae and adult males became the source of the new population the following spring.

The comparative tolerance and accumulation of the trace metals zinc, copper and cadmium in populations of the littoral polychaete worm Nereis diversicolor from three sites: (a) heavily metal-contaminated Dulas Bay in Anglesey, north Wales, (b) the Blackwater estuary, Essex, as a control site, and (c) West Thurrock, the Thames estuary as a site of intermediate metal contamination, were investigated. Worms from Dulas Bay did not show increased tolerance to any metal, but worms from West Thurrock showed significantly increased copper sensitivity compared to the worms from Dulas Bay and the Blackwater. Worms accumulated zinc and copper from sediments with raised zinc and copper concentrations, and all three metals from solution in proportion to dissolved concentration. Accumulated metal was not excreted in 21 days and field concentrations of zinc and copper in the worms differed between sites. There was no evidence for inter-populational differences in accumulation rates of zinc and cadmium from solution, but worms from Dulas Bay accumulated copper from solution at a significantly higher rate than did worms from the other two sites. Nereis diversicolor takes up and accumulates zinc and cadmium from solution at similar rates per unit molar exposure, but cadmium is taken up at a greater rate per unit free metal ion molar exposure. Although N. diversicolor from Dulas Bay is exposed to very high availabilities of zinc and copper, accumulation and detoxification mechanisms are sufficient to cope with the extra metal influx (accentuated for dissolved copper) without selection for a metal-tolerant population.

An evaluation was carried out on the distribution and abundance of the rock shrimp Rhynchocinetes typus in the inshore subtidal zone on the north-central coast of Chile. A number of different benthic community types occur in the region which have different degrees of spatial complexity provided by the primary substratum and by the biotic communities colonizing the substratum. Shrimp abundance was estimated in five different community types including shallow and deep ‘barren grounds’, low encrusting communities, erect suspension feeding associations, and kelp beds of Lessonia trabeculata. The abundance of shrimp was determined on three different types of primary substratum (stones, boulders, rock mass) within each community. Rhynchocinetes typus occurred in all the communities studied, showing the highest abundance on the deep barren grounds and lowest abundance on the shallow barren grounds. The shrimp was found to prefer the stony areas, as these offered the greatest degree of refuge. The abundance of predators was not significantly different among the different communities. However, a decline of abundance of predators was apparent over the deep barren grounds.

The geographic distribution of Verruca stroemia and V. spengleri are reviewed. Verruca stroemia ranges from the White, Barents, Norwegian, and North Seas south to Portugal to the Algarve and to Gorringe Bank. All of the records of this species from the Mediterranean Sea are considered to be V. spengleri. Verruca spengleri occurs in the Azores and Madeira archipelagos, in southern Spain (Cádiz), throughout the Mediterranean Sea from Gibraltar to Lebanon, and in the Black Sea. But a distinct deep-water Verruca species seems to occur in the deep Mediterranean.