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.

Organotin (OT) compounds were determined in surface sediments and mussels Mytilus edulis from two major estuaries of the UK, the Mersey and the Thames, approximately one decade after legislation banning the use of tributyltin (TBT) compounds on small boats. Tributyltin concentrations in Mersey sediments ranged from 0·007–0·173 μg (as Sn) g−1 dry wt, increasing from the most upstream site, Fiddlers Ferry, towards the middle section of the estuary, and were highest at Stanlow, perhaps indicative of sources from the Manchester Ship Canal (MSC). A further peak in TBT concentrations occurred at New Brighton, opposite Liverpool Docks. Tributyltin was the predominant butyltin (BT) species in sediments (approximately 50%). Despite the fact that BTs represented only 4% of the total (HNO3-extractable) tin in sediments there was a linear relationship between these two tin compartments. Furthermore, BTs in mussels were correlative with total extractable tin in sediment, though in contrast to sediments, 85% of the total tin in mussels was made up of BTs, the most predominant of which was TBT. Concentrations of TBT in mussels increased from 0·058 μg Sn g−1 dry wt at the mouth of the estuary to 0·214 μg Sn g−1 dry wt at their upstream limit, close to the entrance to the MSC (Eastham). Triphenyltin (TPT) compounds were detected in only one sediment sample (New Brighton, 0·359 μg Sn g−1 dry wt) and one mussel population (Egremont, 0·022 μg Sn g−1 dry wt). Tributyltin concentrations in sediments from the Thames Estuary were marginally lower (0·002–0·078 μg Sn g−1 dry wt) than those found in the Mersey: highest concentrations were present in the upper estuary and decreased seaward. Again BTs contributed only a small percentage (<1% mean) towards the total tin loading in Thames sediments, but represented most of the tin burden (80%) in mussels. In contrast to sediments, TBT levels in mussels from the Thames Estuary were slightly higher than the Mersey (concentrations ranged from 0·100 μg Sn g−1 dry wt at the mouth to 0·302 μg Sn g−1 dry wt upstream) suggesting that TBT bioavailability is disproportionately higher in the Thames. Phenyltins were not detected in Thames samples.

Water column sampling for nutrients, chlorophyll-a and bacteria was carried out at different time-scales covering 12 hours and one month; ten replicated samples were taken for estimating the stochastic variability. Two sampling stations were established on the north coast of Crete (eastern Mediterranean), one in Heraklion harbour and a second one at an exposed coastal area. All variables measured were significantly higher in the port. Only chlorophyll-a showed an increasing coefficient of variation with increasing time scale at both sampling sites, whereas the other variables showed different patterns between the two sites.

Variability in recovery of the introduced green alga Caulerpa racemosa has been investigated on a subtidal rocky shore in the north-western Mediterranean Sea. Two removal experiments were performed. The first was designed to test the effects of season on the early patterns of recovery of C. racemosa on a rocky bottom and on algal turf. In the second experiment recovery of C. racemosa on the rocky bottom and on algal turf was estimated from July–October 2000, the end of the vegetative period of the alga. Recovery of experimental plots occurred from adjacent populations of C. racemosa by stolon growth. In the first experiment, recovery occurred from August to November in all the experimental units, while no growth was observed during winter and spring. Recovery was significantly higher on algal turf than on rock during all vegetative periods. In both the habitats, recovery was quicker in summer than in autumn, even if differences between dates within each season were also significant. In the second experiment, three months after removal, the mean per cent cover of C. racemosa in algal turf was twice that on rock.

A field experiment investigating the effects of algal removal on benthic invertebrates and estuarine birds was carried out during September and October 2001. A randomized block experimental design was employed and three treatments were used: sites with algal cover maintained, when necessary by the addition of algae, sites with algal cover removed and control sites that were not manipulated in any way. Total invertebrate numbers increased during the experiment, but species varied in their response to the different treatments. Although Hydrobia ulvae showed the greatest increase in cleared sites after two months, there was no significant difference between treatments. Corophium volutator showed significant colonization of cleared sites during the experimental period, and numbers of Phyllodocemaculata also increased in the cleared sites. Results showed that while more sedentary benthic infauna are less capable of adjusting to the affects of algal clearance, more mobile epifauna and polychaetes show an ability to disperse to cleared sites in a relatively short period of time. Wading birds, however, did not enter the study site in any abundance during the experiment. Black-headed gulls (Larus ridibundus) were significantly more abundant in cleared sites than in algal cover-maintained or control sites when foraging.

The micro-erosion patterns of some sponge species belonging to the boring genera Cliona and Aka have been compared. The scanning electron microscope analysis of the excavations of species of the two genera sharing the same substratum clearly indicates that the scars produced on the walls of the boring chambers are different. The pits of Cliona are regular, almost circular and smooth; those of Aka are more irregular and show a multi-layered concentric pattern. These differences constitute a successful means of distinguishing the bio-erosion agents both in recent and in fossil substrata.

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.

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.

A revision of polynoids from the Grand Caribbean region demonstrated that Harmothoe aculeata had been confused with similar species. It is here redescribed and three similar species, H. vossae sp. nov., H. longidentis sp. nov., and H. fuscaspinae sp. nov. are described from the Grand Caribbean region. The four species share certain characteristics such as (a) the presence of papillated antennae and dorsal cirri, and (b) elytra with microtubercles and macrotubercles centred on distinct, separate areolas and surrounded by erect filiform papillae. The species differ mainly in the form and distribution of the macrotubercles, relative thickness between notochaetae and neurochaetae and their ornamentation. A key differentiating these species is included.

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.

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 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.

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.

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 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.

To examine the biological effects of tributyltin (TBT) exposure, the caprellid amphipod, Caprella danilevskii, was exposed to five levels (0, 10, 100, 1000 and 10 000 ng l−1) of TBT during the embryonic stage (five days). Although the female proportion was 36% of the total in the control, the female proportion changed dramatically in the hatched juvenile, i.e. the proportion of females was found to increase to 55·6% at 10 ng l−1, 85·7% at 100 ng l−1, and 81·8% at 1000 ng l−1. All specimens died in 10 000 ng TBTCl l−1 within five days after spawning due to the acute toxic concentration for the species. Reproductive inhibitions such as brood loss and oogenesis inhibition occurred even at 10–100 ng TBTCl l−1 exposures in the short-term period in both parental females and their offspring females. The embryo survival rate in the offspring decreased drastically as the TBT concentrations increased, with the decrease being observed at TBT concentrations as low as 10 ng l−1 (69%) during the five days. In parental females, the survival rate also decreased at more than 100 ng TBTCl l−1, despite movement after five days into seawater with no TBT added. Data suggest that nanogram concentrations of TBT similar to those encountered in coastal waters around the developed countries can directly affect sex proportion, reproduction, and survival in the caprellid.

The phylogenetic relationships within the family Spongicolidae were examined based on a cladistic analysis of 38 adult morphological characters with reference to two outgroup species of the family Stenopodidae. The strict consensus tree identified Microprosthema as the most basal genus, followed by Paraspongicola, Spongicola and the remaining genera. The Spongicoloides represents the most derived genus among spongicolids. The genera Spongicola, Spongicoloides and Spongiocaris should be redefined, because they formed paraphyletic clades. The cladogram indicates that symbiosis with the hexactinellid sponges is coincident with the loss of gills, exopods on maxillipeds 2 and 3, and with the loss of spination on carapace, pereopods, abdomen, tail fan etc. These losses in the spongicolids are thought to be secondarily derived in relation to their sponge-associated habitat.

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.

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.

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.