The spatial and temporal structure of the zoobenthos associated with the invasive red alga Womersleyella setacea was studied in the northern Aegean Sea, Greece. Five replicate quadrats (20×20 cm) were collected, seasonally from July 1997 to August 1998, by SCUBA diving at four sites and two depth levels (15 and 30 m) in the Chalkidiki peninsula. We collected 23,090 specimens representing 278 animal species. Multivariate analysis showed mainly spatial differences in community structure, while the temporal ones were minimal. The ordination of sites showed a clear zonation pattern according to the different algal forms that cover the rocky substrate, with inclination the only environmental factor involved. The epifauna associated with the invasive alga was differently structured compared with three native seaweeds, showing increased species richness and abundance. The filamentous alga W. setacea was dominant in all seasons and depth levels, creating a stable habitat that contributed to the loss of seasonality in zoobenthic community structure.

Pico-size cells with a red fluorescence signature similar to marine free-living prochlorophytes have been detected by flow cytometry throughout the fresh and brackish waters of the Changjiang Estuary in August 2005. These cells could be discriminated from Synechococcus by their lack of orange (phycoerythrin) fluorescence, from Prochlorococcus by their larger side light scatter, and from picoeukaryotes by their smaller side light scatter and much lower red (chlorophyll) fluorescence. The maximum abundances of these Prochlorococcus-like particles reached 3×104 cells ml-1 in the low salinity zone upriver and declined rapidly seaward. While Synechococcus was scarce and Prochlorococcus vanished in the brackish regions, the Prochlorococcus-like cells overnumbered the picoeukaryotes and became the predominant pico-size auto- fluorescing particles there, implying they might play an important role in this estuarine ecosystem and worthy of further investigation.

The colonization of epilithic diatoms on artificial hard substrates (marble, quartzite and slate) was investigated on a seasonal basis in a subtidal site of the northern Adriatic Sea to determine if substrate-dependent differences in colonization occurs and to define the seasonal variations of microepilithic communities in terms of abundance, biomass and community structure. Artificial substrates (smoothed small discs mounted on a Plexiglas sheet) were placed at a depth of 8 m in April 2003, July 2003, January 2004 and February 2004. The discs were collected after 6–7 weeks for counting and taxonomic identification of the diatoms. The community structure of epilithic diatoms showed a dominance of motile species over the entire study period, followed by erect, adnate and tube-dwelling diatoms. Diatom density showed a marked seasonal variability, ranging from 365±407 (winter 2004) to 557156±82602 cells cm-2 (spring 2004). Biomass ranged from 0.02±0.01 to 17.53±3.20 μg C cm-2. Abundance and biomass values did not present any significant differences for the three substrates examined.

This is the first account of the effects of drainage water from an abandoned coal mine on the seaweed community of the intertidal rocky shore in the British Isles. At St Monans, Scotland, along a 250 m transect, the brown climax species Fucus spiralis showed a low abundance in sampling quadrats (17.5%) and small plant size (3.5 cm), close to the outfall, compared to stations at increasing distance from the drainage source. Immediately below the outfall the fucoid community was replaced by a mixture of 12 species of freshwater, brackish and marine Chlorophyta, which did not occur, or only scarcely occurred, at any other transect station. At high tide, ferrous iron concentrations in the water were highest near the source (15.5 mg/l), while salinity was at its lowest (1.1 psu). Accordingly, iron tissue concentrations of apical segments of F. spiralis were also at their highest (12 mg Fe/g dry weight). Reproductive development of F. spiralis may have been inhibited close to the source.

The growth rate response of bacterial communities to the potential increase of dissolved organic matter (DOM) produced by the copepod Acartia tonsa was assessed in experiments conducted in three stations representing three contrasting aquatic environments (coastal embayment, shelf and ocean). Bacterial assemblages were inoculated in filtered seawater where A. tonsa had previously grazed. Utilization of DOM over time was evaluated after the addition of bacterial inoculums as the biomass changes in both ‘control’ and ‘copepod’ treatments. In the embayment and ocean a high bacterial growth was observed in the treatments with seawater where copepod were feeding. Additional field measurements of bacterial, primary production and zooplankton biomass support the idea that bacterial communities living in oceanic environments can be efficient to utilize the newly available substrate. Copepods play a key role not only as conveyors of carbon up through the classical food-web, but also generated significant amounts of bacterial substrate in the microbial loop food-web.

Marine populations are typically connected over greater spatial scales than their terrestrial counterparts due to many species having a highly dispersive, planktonic larval phase. However, high levels of larval mortality in the plankton may reduce connectivity between populations. The effect of turbulence on larval mortality was investigated under natural conditions in a field experiment. Larvae were collected before and after being subjected to turbulent tidal flow from a marine reserve, with differential mortality being observed between taxa. Thin-shelled veligers of gastropods and bivalves showed significantly increased mortality, while barnacle nauplii and cyprids, bryozoan cyphonaute larvae and polychaete trochophores showed no effect of turbulent tidal transport. Where appropriate, marine reserve design should account for the reduced connectivity between populations associated with turbulent tidal transport between reserve and adjacent areas.

Bathymetric distribution data were compiled on benthic Medusozoa (Cnidaria) of the Bay of Biscay and nearby seas. The area of study extended from 42°N to 48°30′N, and westwards to 10°W. The depth range of each species was traced in a review of the literature. The number of species in each of several depth zones is summarized here: intertidal, intertidal–30 m, 30–100 m, and thereafter at 100 m depth intervals throughout the entire column (0–5000 m). Some 200 species were included (six Scyphozoa, four Staurozoa, 190 Hydrozoa). Of these, 196 could be ascribed to the Coastal Realm (0–200 m) (118 exclusives; 60% of the fauna) and Deep Benthic Realm (200+m) (31 exclusives;16%), with 47 species inhabiting both (24%). Eighty-eight species (45%) were present intertidally. Biodiversity was highest above the summer thermocline (30 m) (133 species, 67%), and no species have been recorded from depths greater than 4706 m. Beyond the thermocline, biodiversity dropped with increasing depth. A significant change occurred in the 30–100 m interval (123 to 78 species; Distinctiveness=51%), although all intervals down to the 300 m isobath exhibited substantial changes. Most species in the Deep Benthic Realm thrive on the upper part of the slope (200–800 m; 50 species). Biodiversity appeared homogeneous across wide bathymetric ranges in deep bathyal and abyssal regions, perhaps due to unique vertical biocenological units. Thus, 15 species are known between 1400 and 2000 m, and four between 3100 and 4300 m. Fifty-four species were considered eurybathic (34%), with some showing impressive bathymetric ranges of over 4000 m, but most species were stenobathic (106, 66%).

As with data on benthic medusozoans from South Africa, the north-western Atlantic, the Arctic, and the warm western Atlantic (Bermuda), bathymetric biodiversity was highest in the first 100 m, with a substantial drop below that in species numbers on the shelf and at the beginning of the bathyal. While numbers of species may vary widely from one geographical region to another, such variations are due to differences in biodiversity in the upper 100 m. Hydroid species richness in the deep bathyal and abyssal is similar and always low. Worldwide, benthic medusozoan biodiversity is highest at shallow depths, and these organisms normally seem to be minor components of deep benthos. Very likely, the graph of biodiversity at increasing depth is similar worldwide for the Hydrozoa.

The phylogenetic relationships of Euthelepus (Polychaeta: Terebellidae: Thelepodinae) were studied by means of a parsimony analysis of 40 external characters. The ingroup terminals included four species of Euthelepus, and the outgroup included 14 species of eight Thelepodinae genera, three belonging to the subfamily Terebellinae, one species of Trichobranchinae, and one species of Polycirrinae. Only two most parsimonious cladograms were found. However, the analysis revealed a large number of homoplastic characters supporting the thelepodin branches. The monophyly of the genus Euthelepus was not supported, and the monophyly of the other thelepodin genera, as well as the entire subfamily, is questioned. The large number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses by using additional characters. A re-classification based on phylogenetic results must be considered.

The Solent European Marine Sites contain many tiers of habitat and species conservation, but also high levels of bait collection. Effective management strategies must be founded on up-to-date and locally based information from relevant studies of the impacts; these have been lacking for the collection of Nereis virens, a key bait species. The impacts on macrofauna were assessed through two approaches; (a) undug and dug sites in the Solent were compared over two years of repeat sampling; and (b) monitoring the long-term effects of simulated bait collection at an undug site through five years of yearly sampling. Dug sites had significantly higher densities of N. virens, but the mean weight was found to be significantly lower than those collected from the undug sites, but percentage maturity was not different. Organic content and sediment particle sizes differed between sites, and only the presence of gravel had a significant positive correlation with density. No clear patterns of other macrofauna species present were evident, although there was a significantly lower density of the terebellid polychaete Neoamphitrite figulus at the dug sites. Simulated bait collection did not alter overall macrofauna diversity, but certain species were affected. Abundance of N. figulus and the commensal Harmothoë glabra remained consistently lower in the dug area, whilst Cerastoderma edule numbers were reduced initially, but recovered. Numbers of Nephtys hombergii declined in both areas, but at a significantly greater rate in the dug area. A general decline in the abundance of many species, irrespective of digging, occurred over the period. The importance of these changes in Nereis virens populations and in the macrofauna community needs to be investigated prior to any management decisions on collection.

A new genus and one new species of free-living marine nematodes Paramarylynnia gen. nov., Paramarylynnia subventrosetata sp. nov. from the Yellow Sea, China are described and illustrated. Paramarylynnia gen. nov. is characterized by a cuticle with transverse rows of even dots; absence of lateral differentiation; gubernaculum large and dilated at the distal end, no distal dentation; precloacal supplements absent; tail conico-cylindrical.The type species of Paramarylynnia gen. nov. is Paramarylynnia subventrosetata sp. nov.

The patterns of distribution, abundance and reproduction of the Indo-Pacific barnacle Balanus amphitrite were surveyed at Costa do Sol mangrove, Maputo Bay, southern Mozambique using stratified sampling design. Balanus amphitrite exhibited a spatial variation in which high numbers of individuals colonized the upper stratum in comparison to the lower stratum. Seasonal abundance of B. amphitrite was greater in the upper stratum and declined in June and September. In contrast, very high densities of individuals were recorded in winter in the lower stratum. Gonad cycle showed continuous trend and release of embryos mainly took place in winter (May–July). There was a strong quadratic effect of temperature on breeding activity of B. amphitrite, with females continuing to brood at lower temperatures. Egg numbers increased linearly with female size. The success of the reproductive activity may be synchronized within the species, enhancing the establishment and colonization of B. amphitrite in the study area.

The present study describes the reproductive cycle and population structure of the intertidal crab Petrolisthes laevigatus, an abundant inhabitant of the upper rocky intertidal zone, as well as the relationship between seasonal patterns in the release of its planktonic larvae and recruiting. A total of 22900 individuals was collected along the coast of southern Chile between May 2001 and March 2003.The structure and density of the adult population (males and females) was relatively constant throughout the study period, although seasonal variations were observed in these two parameters of the benthic population (males, females, juveniles and megalopae), principally due to the incorporation of new individuals (recruitment) into the intertidal zone. Petrolisthes laevigatus presented a prolonged reproductive period. Females with initial eggs were present from the end of summer through to the middle of the following summer (11 months) and the breeding season lasted seven months (from August to February), as reflected in the six months of intertidal settlement (October–March).The interannual patterns and variations observed in the settlement along the southern Chilean coastline were related to the patterns in the abundance of potential released planktonic larvae. Petrolisthes laevigatus, unlike most temperate species, has a broad reproductive and settlement period in the south of Chile, which allows a highly stable structure and population abundance in this intertidal zone.

Waves breaking on rocky shorelines impart large forces on intertidal organisms, sometimes dislodging individuals. Dislodged individuals may be deposited in habitats that have a greater risk of predation or that prevent return to preferred regions on the shore. Thus, dislodgement is often assumed to be lethal. We experimentally dislodged Littorina keenae snails from high in the intertidal zone to test the likelihood of survival. Under a variety of wave conditions, we measured return rates to the high shore of 54–90%, so in this species, dislodgement is not equal to death. Snails showed a strong preference for returning to the approximate tidal height from which they were dislodged, but we found no evidence of widespread homing behaviour back to the original site of dislodgement.

The main functional characteristics of haemocytes from the common periwinkle Littorina littorea (phagocytic ability, acid phosphatase activity, cytotoxic properties and generation of reactive oxygen intermediates) were investigated. The blood cells of L. littorea demonstrated phagocytic activity for zymozan particles in both plasma and seawater. However, the level of phagocytosis in plasma was higher than in seawater, suggesting the presence of some soluble factors with opsonizing activity for yeast cell walls in the snail haemolymph. Acid phosphatase was detected in haemocytes following phagocytosis of zymosan. Zymosan particles as well as soluble inducers of respiratory burst (mannan, phorbol-myristate acetate, lipopolysaccharide from Escherichia coli) were shown to trigger superoxide anion production in L. littorea blood cells as evidenced by nitroblue tetrazolium (NBT) reduction. Haemocytes exposed simultaneously to both inducer and the superoxide scavenger enzyme—superoxide dismutase demonstrated a lower ability to reduce nitrobluetetrazolium. Periwinkle blood cells showed plasma-independent cytotoxic activity for human erythrocytes which may be due to the release of superoxide intermediates into the extracellular environment. These results, together with previously obtained data, suggest that haemocytes are the main effectors in the internal defence system of L. littorea, with humoral factors playing an accessory role in recognition and elimination of pathogens.

The ultrastructure of sperm of an acochlidian opisthobranch is described for the first time in detail, in the tiny, gonochoristic Microhedyle remanei (Microhedylidae) from Bermuda. Transmission electron microscopy (TEM) shows the spermatozoa of M. remanei sharing many plesiomorphic features with opisthobranch gastropods, such as having an apical spiral nucleus with a basal invagination filled with a bell-shaped centriolar derivative; there is a single glycogen helix embedded into matrix and paracrystalline material. Sperm of M. remanei are characterized by possessing a strongly helically coiled nucleus with up to five keels terminating into one very prominent and intertwined keel. The sperm midpiece shows the glycogen helix which is very densely arranged. This clearly differs from Hedylopsis ballantinei, a member of the related acochlidian family Hedylopsidae, where three glycogen helices with different lengths and a probably much shorter nucleus are present. This variation among acochlidian sperm may be phylogenetically relevant and may be related to special acochlidian reproductive features such as sperm transfer via hypodermic injection or dermal fertilization via spermatophores.

The increasing occurrence of imposex in marine gastropods has been related to their exposure to the tri-substituted organotin compounds tributyltin (TBT) and triphenyltin (TPhT), which have been widely used as antifouling agents, and has been documented for more than 200 gastropod species. Odontocymbiola magellanica, a large benthic neogastropod, showed 85–100% imposex near harbours with high marine traffic in Patagonia. We evaluated if, as predicted by the energy allocation hypothesis, females with imposex (FWI) were on average larger and/or heavier than normal individuals, and if there were differences in shell morphometry associated with imposex, using both univariate and multivariate approaches. We detected differences in two morphometric variables, but no overall effect in shell shape, and ~10% of reduction in body weight in FWI. In addition, the multivariate index of size suggested a positive effect on FWI, in contrast to univariate analyses showing no differences in shell length. The present results demonstrate that responses to TBT vary among gastropod species and that the energy allocation hypothesis may be useful only under certain conditions.

This article reports on four different juvenile reef fish species, Polydactylus virginicus, Haemulon aurolineatum, H. steindachneri and Carangoides bartholomaei swimming along with schools of the caribbean reef squid Sepioteuthis sepioidea. Three different behaviours were observed. This is the first record of this squid species on Brazilian reef habitats. We suggest that this behaviour is mainly related to protection for juvenile fish against potential pelagic predators.

The reproductive strategies of the sea urchin, Paracentrotus lividus, were studied in the Bay of Tunis. Samples were collected monthly, from September 1993 to August 1995, in two sites which differ in their marine vegetation and their exposure to wave action. Histological examination demonstrated a cycle of gametogenesis with six reproductive stages and a main breeding period occurring between April and June. Gonad indices varied between sites and years, the sheltered site presenting a higher investment in reproduction.This difference was essentially induced by the largest sea urchins (above 40 mm in diameter). Repletion indices showed a clear pattern without difference between sites and years. The sea urchin increase in feeding activity was controlled by the need to allocate nutrient to the gonad during the mature stage. But the gonad investment was not correlated with the intensity of food intake. Hydrodynamic conditions might play a key role in diverting energy to the maintenance in an exposed environment at the expense of reproduction.

The regular sea urchin Lytechinus variegatus, a species previously reported from areas of reduced salinities, and Arbacia lixula, a species unreported from diluted waters, were submitted to seawater dilution or seawater dilution in magnesium-supplemented waters. Seawater (35 psu) was either proportionally diluted with filtered dechlorinated tap water (30 psu, 25 psu), or diluted and supplemented with magnesium as MgCl2 (30+Mg, 25+Mg), up to full-strength seawater Mg2+ levels (35 psu, ~54 mM Mg2+). Magnesium supplementation was intended to verify the interfering effect of magnesium on osmo-ionic concentrations of the coelomic fluid (CF) of two ecologically distinct species of sea urchins. After 6 h in control (35 psu) or experimental seawater, CF samples were withdrawn by puncturing through the peristomial membrane. Coelomic fluid osmolality ([Osm]), and concentrations of ([Na+]), ([Cl-]), ([Mg2+]) and ([K+]) were measured for both species. Under all conditions, L. variegatus displayed higher CF osmolality, [Na+], and [K+] values than the water (and A. lixula). Comparatively, L. variegatus is designated as a‘hyper-conformer’, while A. lixula is an ‘iso-conformer’. The CF [Mg2+] showed no evidence of being controlled by either species. Mg2+ supplementation in diluted seawater affected Mg2+ and Cl- levels only. Na+ appears to be taken up actively by L. variegatus, rendering its CF mostly hyper-ionic for Na+ (and hyperosmotic) relative to external seawater. The different gradients observed with the different ions suggest selective permeabilities or ion regulation by L. variegatus.

An in situ tagging technique for the long-spined sea urchin Diadema aff. antillarum, suitable for carrying out short and medium term ecological studies is described. It is a simple method in which external nylon tags are anchored in holes drilled through the urchin test. The technique was tested in the field and found to be effective for individuals of more than 20 mm test diameter in terms of survival and tag retention rates.