The spatial and temporal structure of the zoobenthos associated with the invasive red alga Womersleyellasetacea 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. Multivariateanalysis showed mainly spatial differences in community structure, while the temporal ones wereminimal. The ordination of sites showed a clear zonation pattern according to the different algal formsthat cover the rocky substrate, with inclination the only environmental factor involved. The epifauna associatedwith the invasive alga was differently structured compared with three native seaweeds, showingincreased species richness and abundance. The filamentous alga W. setacea was dominant in all seasonsand depth levels, creating a stable habitat that contributed to the loss of seasonality in zoobenthiccommunity structure.

Pico-size cells with a red fluorescence signature similar to marine free-living prochlorophytes have beendetected by flow cytometry throughout the fresh and brackish waters of the Changjiang Estuary in August2005. 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 sidelight scatter and much lower red (chlorophyll) fluorescence. The maximum abundances of theseProchlorococcus-like particles reached 3×104 cells ml-1 in the low salinity zone upriver and declined rapidlyseaward. While Synechococcus was scarce and Prochlorococcus vanished in the brackish regions, theProchlorococcus-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 andworthy of further investigation.

The colonization of epilithic diatoms on artificial hard substrates (marble, quartzite and slate) wasinvestigated on a seasonal basis in a subtidal site of the northern Adriatic Sea to determine ifsubstrate-dependent differences in colonization occurs and to define the seasonal variations of microepilithiccommunities 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, July2003, January 2004 and February 2004. The discs were collected after 6–7 weeks for counting and taxonomicidentification of the diatoms. The community structure of epilithic diatoms showed a dominance ofmotile species over the entire study period, followed by erect, adnate and tube-dwelling diatoms. Diatomdensity showed a marked seasonal variability, ranging from 365±407 (winter 2004) to 557156±82602cells cm-2 (spring 2004). Biomass ranged from 0.02±0.01 to 17.53±3.20 μg C cm-2. Abundance andbiomass 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 seaweedcommunity of the intertidal rocky shore in the British Isles. At St Monans, Scotland, along a 250 mtransect, 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 thedrainage source. Immediately below the outfall the fucoid community was replaced by a mixture of 12species 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 thesource (15.5 mg/l), while salinity was at its lowest (1.1 psu). Accordingly, iron tissue concentrations of apicalsegments of F. spiralis were also at their highest (12 mg Fe/g dry weight). Reproductive development ofF. 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 stationsrepresenting three contrasting aquatic environments (coastal embayment, shelf and ocean). Bacterialassemblages were inoculated in filtered seawater where A. tonsa had previously grazed. Utilization ofDOM 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 inthe treatments with seawater where copepod were feeding. Additional field measurements of bacterial,primary production and zooplankton biomass support the idea that bacterial communities living inoceanic environments can be efficient to utilize the newly available substrate. Copepods play a key rolenot only as conveyors of carbon up through the classical food-web, but also generated significant amountsof bacterial substrate in the microbial loop food-web.

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

Bathymetric distribution data were compiled on benthic Medusozoa (Cnidaria) of the Bay of Biscay andnearby seas. The area of study extended from 42°N to 48°30′N, and westwards to 10°W. The depth range ofeach species was traced in a review of the literature. The number of species in each of several depth zones issummarized here: intertidal, intertidal–30 m, 30–100 m, and thereafter at 100 m depth intervalsthroughout the entire column (0–5000 m). Some 200 species were included (six Scyphozoa, fourStaurozoa, 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 summerthermocline (30 m) (133 species, 67%), and no species have been recorded from depths greater than4706 m. Beyond the thermocline, biodiversity dropped with increasing depth. A significant changeoccurred in the 30–100 m interval (123 to 78 species; Distinctiveness=51%), although all intervals downto the 300 m isobath exhibited substantial changes. Most species in the Deep Benthic Realm thrive on theupper part of the slope (200–800 m; 50 species). Biodiversity appeared homogeneous across wide bathymetricranges 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-fourspecies were considered eurybathic (34%), with some showing impressive bathymetric ranges of over4000 m, but most species were stenobathic (106, 66%).

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

The phylogenetic relationships of Euthelepus (Polychaeta: Terebellidae: Thelepodinae) were studied bymeans of a parsimony analysis of 40 external characters. The ingroup terminals included four species ofEuthelepus, and the outgroup included 14 species of eight Thelepodinae genera, three belonging to thesubfamily Terebellinae, one species of Trichobranchinae, and one species of Polycirrinae. Only two mostparsimonious cladograms were found. However, the analysis revealed a large number of homoplastic characterssupporting the thelepodin branches. The monophyly of the genus Euthelepus was not supported, andthe monophyly of the other thelepodin genera, as well as the entire subfamily, is questioned. The largenumber of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypothesesby 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 highlevels of bait collection. Effective management strategies must be founded on up-to-date and locally basedinformation from relevant studies of the impacts; these have been lacking for the collection of Nereis virens, akey bait species. The impacts on macrofauna were assessed through two approaches; (a) undug and dugsites in the Solent were compared over two years of repeat sampling; and (b) monitoring the long-termeffects of simulated bait collection at an undug site through five years of yearly sampling. Dug sites hadsignificantly higher densities of N. virens, but the mean weight was found to be significantly lower than thosecollected from the undug sites, but percentage maturity was not different. Organic content and sedimentparticle sizes differed between sites, and only the presence of gravel had a significant positive correlationwith density. No clear patterns of other macrofauna species present were evident, although there was asignificantly lower density of the terebellid polychaete Neoamphitrite figulus at the dug sites. Simulated baitcollection 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 Cerastodermaedule 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 populationsand in the macrofauna community needs to be investigated prior to any management decisions oncollection.

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

The patterns of distribution, abundance and reproduction of the Indo-Pacific barnacle Balanus amphitritewere surveyed at Costa do Sol mangrove, Maputo Bay, southern Mozambique using stratified samplingdesign. Balanus amphitrite exhibited a spatial variation in which high numbers of individuals colonized theupper stratum in comparison to the lower stratum. Seasonal abundance of B. amphitrite was greater in theupper stratum and declined in June and September. In contrast, very high densities of individuals wererecorded in winter in the lower stratum. Gonad cycle showed continuous trend and release of embryosmainly took place in winter (May–July). There was a strong quadratic effect of temperature on breedingactivity of B. amphitrite, with females continuing to brood at lower temperatures. Egg numbers increasedlinearly 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 Petrolistheslaevigatus, an abundant inhabitant of the upper rocky intertidal zone, as well as the relationship betweenseasonal patterns in the release of its planktonic larvae and recruiting. A total of 22900 individuals wascollected along the coast of southern Chile between May 2001 and March 2003.The structure and density ofthe adult population (males and females) was relatively constant throughout the study period, althoughseasonal variations were observed in these two parameters of the benthic population (males, females, juvenilesand 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 theend of summer through to the middle of the following summer (11 months) and the breeding season lastedseven 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 coastlinewere 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, whichallows a highly stable structure and population abundance in this intertidal zone.

Waves breaking on rocky shorelines impart large forces on intertidal organisms, sometimes dislodgingindividuals. Dislodged individuals may be deposited in habitats that have a greater risk of predation or thatprevent return to preferred regions on the shore. Thus, dislodgement is often assumed to be lethal. Weexperimentally dislodged Littorina keenae snails from high in the intertidal zone to test the likelihood ofsurvival. Under a variety of wave conditions, we measured return rates to the high shore of 54–90%, soin this species, dislodgement is not equal to death. Snails showed a strong preference for returning to theapproximate tidal height from which they were dislodged, but we found no evidence of widespread homingbehaviour 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 zymozanparticles in both plasma and seawater. However, the level of phagocytosis in plasma was higher than inseawater, suggesting the presence of some soluble factors with opsonizing activity for yeast cell walls in thesnail 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. littoreablood cells as evidenced by nitroblue tetrazolium (NBT) reduction. Haemocytes exposed simultaneouslyto both inducer and the superoxide scavenger enzyme—superoxide dismutase demonstrated a lower abilityto reduce nitrobluetetrazolium. Periwinkle blood cells showed plasma-independent cytotoxic activity forhuman erythrocytes which may be due to the release of superoxide intermediates into the extracellularenvironment. These results, together with previously obtained data, suggest that haemocytes are the maineffectors in the internal defence system of L. littorea, with humoral factors playing an accessory role inrecognition and elimination of pathogens.

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

The increasing occurrence of imposex in marine gastropods has been related to their exposure to thetri-substituted organotin compounds tributyltin (TBT) and triphenyltin (TPhT), which have been widelyused as antifouling agents, and has been documented for more than 200 gastropod species. Odontocymbiolamagellanica, a large benthic neogastropod, showed 85–100% imposex near harbours with high marinetraffic in Patagonia. We evaluated if, as predicted by the energy allocation hypothesis, females withimposex (FWI) were on average larger and/or heavier than normal individuals, and if there were differencesin 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% ofreduction in body weight in FWI. In addition, the multivariate index of size suggested a positive effect onFWI, in contrast to univariate analyses showing no differences in shell length. The present results demonstratethat responses to TBT vary among gastropod species and that the energy allocation hypothesis maybe 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 squidSepioteuthis sepioidea. Three different behaviours were observed. This is the first record of this squid specieson Brazilian reef habitats. We suggest that this behaviour is mainly related to protection for juvenile fishagainst 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 theirmarine vegetation and their exposure to wave action. Histological examination demonstrated a cycle ofgametogenesis with six reproductive stages and a main breeding period occurring between April andJune. Gonad indices varied between sites and years, the sheltered site presenting a higher investment inreproduction.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 urchinincrease in feeding activity was controlled by the need to allocate nutrient to the gonad during themature stage. But the gonad investment was not correlated with the intensity of food intake. Hydrodynamicconditions might play a key role in diverting energy to the maintenance in an exposedenvironment 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 orseawater dilution in magnesium-supplemented waters. Seawater (35 psu) was either proportionallydiluted with filtered dechlorinated tap water (30 psu, 25 psu), or diluted and supplemented with magnesiumas MgCl2 (30+Mg, 25+Mg), up to full-strength seawater Mg2+ levels (35 psu, ~54 mM Mg2+). Magnesiumsupplementation was intended to verify the interfering effect of magnesium on osmo-ionic concentrations ofthe coelomic fluid (CF) of two ecologically distinct species of sea urchins. After 6 h in control (35 psu) orexperimental seawater, CF samples were withdrawn by puncturing through the peristomial membrane.Coelomic fluid osmolality ([Osm]), and concentrations of ([Na+]), ([Cl-]), ([Mg2+]) and ([K+]) weremeasured 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 orion regulation by L. variegatus.

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