A new interstitial hydroid, Sympagohydra tuuli, has been collected from the three-dimensional brine channel system of the coastal fast ice off Barrow, Alaska (71°N 156ºW) in 2003 to 2006. This is the first cnidarian species described from the sea ice interstitial habitat. A morphological and systematic account of the new species is provided here. The hydroid stage is represented by solitary naked polyps, which become almost spherical under contraction. Body length can vary from 200 µm to >1 mm according to the degree of relaxation. The aboral side is extensible into a tubular foot-like projection made by epidermal tissue only, a typical feature of representatives of Protohydridae, order Capitata. However, in contrast to the other two known Protohydridae species, S. tuuli is characterized by three to four solid filiform tentacles, armed with microbasic mastigophore and desmoneme cnidocysts, and located at the base of a short hypostome bearing stenoteles. A small number of mastigophores are also scattered along the body column. Due to its unique combination of features, this taxon is designated here as a new species, and the new genus Sympagohydra is established as a new member of the class Hydroidomedusa, subclass Anthomedusae, order Capitata, family Protohydridae, to accommodate S. tuuli.

Investigating the spatio-temporal patterns of planktonic larvae is fundamental to studies regarding stock assessment and larval dispersal of commercial and non-commercial, i.e. invasive or rare marine invertebrates. Because of the difficulty involved in morphological identification of marine invertebrate larvae, various molecular methods based on PCR have been used to enhance taxonomic resolution. In previous studies, different methods for the preservation or pretreatment of larvae were applied in each case. However, no comparative studies have been conducted to determine the optimal method for PCR testing for bivalve larvae, and no information is available regarding the selection of an appropriate method.

This study compared the PCR success rate of 6 pretreatment methods for larvae of the Mediterranean blue mussel, which was preserved using different fixatives (70% ethanol, 100% ethanol, 70% acetone and 10% formalin). The results revealed that the success rate of PCR was different for each pretreatment; moreover, the use of ammonium sulphate and Tween 20 buffer with proteinase K digestion was found to be the most effective method. Some pretreatments showed lower success rates for long-fixed larvae than for short-fixed larvae for formalin-fixed larvae; however, the success rate of PCR amplification for ethanol-fixed larvae pretreated by this method did not decrease through 1-year fixation. In addition, this pretreatment showed a high success rate for different fixation periods. These findings suggest that the selection of the pretreatment method is critically important for successfully amplifying larval DNA and that the pretreatment involving the use of ammonium sulphate prior to PCR amplification enables the use of fixatives for preserving bivalve larvae. This method will be utilized in various field studies and molecular genetic studies.

Deep-sea hydrothermal vents display extreme and highly variable environmental conditions that are expected to be among the most important factors structuring associated benthic populations and communities. We tested this assumption, focusing on the distribution of gastropods, as well as on the demographic population structure and reproductive biology of one dominant gastropod species in zones characterized by alvinellid polychaetes and vestimentiferan tubeworms. A total of 14 biological samples from both types of habitats were collected at three sites on the East Pacific Rise 13°N vent field in May 2002. At all vents except one, the physico-chemical environment was described in two steps: (1) pH, total sulphide and reduced iron concentrations have been measured in situ in Alvinella habitats and correlations to temperature were assessed at the scale of each sampled vent; and (2) assuming the consistency of these relationships within a single edifice, ranges of physico-chemical factors were estimated for each biological sample from the corresponding fine scale temperature measurements. A total of 11 gastropod species were identified from all samples and 2 main faunal assemblages were distinguished: one dominated by Lepetodrilus elevatus in the alvinellid zone as well as in the vestimentiferan zone, and one dominated by the peltospirids Nodopelta heminoda, N. subnoda and Peltospira operculata confined to the alvinellid zone. Peltospirid gastropods were dominant over lepetodrilid gastropods in the more acidic, sulphide-richer, and hotter environments. Although this pattern could be related to specific physiological tolerances to temperature and sulphide toxicity, the weak correlation between community structure and physico-chemical variables suggests that additional factors are also involved. Particularly, the low species richness and the overwhelming dominance of L. elevatus in one faunal assemblage suggest that this species may outcompete peltospirids and greatly affect community structure. This hypothesis is supported by large differences in the demographic structure and reproductive biology of L. elevatus between the 2 faunal assemblages.

The north-eastern Atlantic sacoglossan gastropod Elysia viridis was studied on littoral and sublittoral shores of the British Isles from 2001 to 2007 to evaluate its potential role in the known decline of the invasive green alga Codium fragile ssp. fragile. Across its European range, this sacoglossan associates with eight genera of algal hosts within three algal orders and two divisions; these hosts include native and introduced macroalgae. The ‘specialist’ herbivore was investigated primarily within the rocky shore community at Lough Hyne Marine Reserve, County Cork, south-west Ireland, with comparative information from surveys of 95 other sites in the British Isles. In Lough Hyne, E. viridis associated with the green algae Codium, Cladophora and Chaetomorpha as well as the red alga Griffithsia. The sacoglossan associated with Codium, Cladophora and Chaetomorpha as well as the red alga Halurus in Devon, Isle of Wight and the Channel Islands. Recruitment of E. viridis to Codium spp. in the lough was substantially higher than in most areas of the British Isles with 100% of the Codium hosts attacked during annual September surveys. The strong autumn pulse of sacoglossan recruitment, coupled with the asynchronous population dynamics compared to other shores, indicates retention of planktotrophic larvae within the lough. The previously reported decline in sacoglossan density with tidal level was hypothesized to be caused by sublittoral predators. Although our experiments failed to demonstrate an effect by large predators, the foraging of the abundant fingerling fish and small crabs could not be tested conclusively. Field experiments were consistent with the interpretation of intense sacoglossan herbivory in certain areas of the lough. However, even if the sacoglossans contribute to the local decline of C. fragile in the lough, they cannot account for the regional decline of the alga on the north-eastern Atlantic shores.

Surveys by digital side-scan sonar, RoxAnnTM acoustic ground discrimination systems, multibeam echosounder and a sub-bottom profiling system showed that a Modiolus modiolus reef, in the Irish Sea off Pen Llŷn, north-west Wales, had a distinctive morphology and acoustic characteristics. The extent of the reef could therefore be determined and the benthic structure reliably mapped. The biogenic reef is in an area with moderately strong tidal currents and overlays lag gravel and cobbles with patchy sand veneers. The mussels form an undulating surface, orientated perpendicular to the current, with an average wavelength of 11.7 m and amplitude of 0.24 m that is significantly different from the surrounding seabed. Reef deposits reach a thickness of 1 m on top of the underlying lag gravels. The characteristic reef surface morphology helps distinguish the reef from the surrounding seabed on side-scan sonar and multibeam echosounder records and the undulations create the spatial complexity that influences the small-scale distribution of the associated epifauna, and infauna, reported in papers II and III of this series. The M. modiolus reef was recorded in the same location 40 y ago and has probably persisted there for over 150 y. Monitoring implications are discussed.

Habitat distribution models are one of the most up to date methods to study the habitat usage of wildlife populations. They allow animal distribution to be related to environmental features and also the prediction of the distribution of animals based on this relationship. Seasonal aerial surveys were conducted in central Spanish Mediterranean waters from June 2000 to March 2003 to obtain information on the distribution of cetacean species. Data from the three most common cetacean species (striped dolphin, Stenella coeruleoalba, bottlenose dolphin, Tursiops truncatus, and Risso's dolphin, Grampus griseus) were related, using generalized linear models, to local environmental features: depth, slope, sea surface temperature and chlorophyll concentration. For bottlenose dolphins, no significant relationship was found with any covariate and no dolphins were observed in waters greater than 1000 m. The distribution of both striped and Risso's dolphin was significantly related to depth. The striped dolphin showed a preference for waters between 900 and 1500 m deep and Risso's dolphin for waters more than 1500 m deep. In addition, for the latest two species, maps of distribution were predicted by means of the spatial models. The areas of higher probabilities of occurrence coincide to a large extent with the marine protected areas previously proposed for the conservation of oceanic cetacean species.

The blue mussel, Mytilus edulis, and the Mediterranean mussel, Mytilus galloprovincialis, occur widely over much of northern Europe, and wherever they are sympatric they hybridize. The hybrid zone is large, ranging from western France to the north of Scotland, and is spatially complex, containing a mixture of pure, hybrid and introgressed individuals. Results from an Irish study in 1981, using partially diagnostic allozyme markers, indicated that mussels on the Irish Sea coast were solely M. edulis, but on Atlantic wave-exposed shores, and to a much lesser extent on wave-protected shores, mussels comprised an interbreeding mixture of M. edulis and M. galloprovincialis. In this study mussels were analysed from 20 locations on Irish coasts, using the Me15/16 nuclear DNA marker. The results showed a high frequency of M. galloprovincialis (0.378 ± 0.198) and hybrid (0.429 ± 0.175) genotypes, and correspondingly low frequencies of the M. edulis genotype (0.194 ± 0.107) at both exposed and sheltered locations on Atlantic coasts, indicating no apparent advantage for the M. edulis genotype at wave-protected sites. Mytilus galloprovincialis was virtually absent from the Irish Sea. Mussels in this area may be a self-recruiting population of M. edulis due to thermal front development at the northern and southern entrances to the Irish Sea in late spring, thereby preventing an influx of spring-spawned Mytilus larvae. The apparent change in the genetic composition of mussels on Atlantic coasts since the early 1980s could be related to climate change, or to aquaculture practice in Ireland whereby mussels from exposed shores are used to seed ropes in wave-protected bays and estuaries.

The relative growth of the fiddler crab Uca cumulanta was studied, primarily to determine the size at the onset of sexual maturity for a mangrove population in the estuary of the Patitiba River, Paraty, Rio de Janeiro state, Brazil. The evaluation of the morphological sexual maturity of U. cumulanta was performed using the allometric technique. The relationships that most precisely indicated the size at onset of sexual maturity were carapace length (CL) vs propodus length for males and CL vs abdomen width for females. Males and females are mature at 5.25 and 4.75 mm CL, respectively. The remarkable ontogenetic changes observed in the allometric growth of the male major cheliped and the female abdomen, indicate that growth of these structures is closely connected to the timing of sexual maturity. The relative size at onset maturity obtained for this species was 0.68 and this index was compared to that seen in other species in the genus.

The white-beaked dolphin (Lagenorhynchus albirostris) and short-beaked common dolphin (Delphinus delphis) are two of the most abundant delphinid species in shelf waters around the United Kingdom (UK) and Republic of Ireland (ROI) in the summer season (May–October). As these two species have similar habitat preferences and diets, it might be expected that they would partition their otherwise shared niche to reduce the potential for competition at this time of year. This study used 569 sightings of the two species, collected from shelf waters (<200 m water depth) in the summer season between 1983 and 1998, to investigate whether there is evidence of widespread niche partitioning based on water temperature in this area. Below 13°C, white-beaked dolphins were dominant with 96% of sightings comprising this species. In contrast, above 14°C, 86% of sightings comprised common dolphins. A classification tree analysis found that of the four eco-geographical variables analysed (water depth, seabed slope, seabed aspect and sea surface temperature), temperature was the most important variable for separating the occurrence of the two species. These results are consistent with widespread temperature-based niche partitioning between white-beaked and common dolphins in shelf waters around the UK and ROI. As temperature is important in determining the relative distribution of these species, the range of the white-beaked dolphin might be expected to contract in response to increasing sea temperature resulting from global climate change, while that of the common dolphin may expand.

The ecdysteroids ecdysone (E), 20-hydroxyecdysone (20E) and ponasterone A (PoA) were measured in the haemolymph, hepatopancreas and oocytes of female shore crabs Carcinus maenas during the moulting cycle and during oocyte maturation using HPLC-MS. In the haemolymph, ecdysteroid titres varied over the moulting cycle with high levels during premoult and low levels during postmoult and intermoult, however, no significant change in haemolymph ecdysteroid titres was observed in relation to oocyte development. In the hepatopancreas, PoA levels were high during premoult but low during postmoult and intermoult. This is in contrast to E and 20E where levels remained high from early intermoult (C1) until late premoult (D3) and only decreased during postmoult. In the oocytes, ecdysteroid levels were low during postmoult and for 20E and PoA also during late premoult D2 and D3. In contrast, all three ecdysteroids were observed to increase in the oocytes during oocyte development, in particular E and PoA. The present study demonstrates that changes in haemolymph ecdysteroid titres relate to changes in moulting status and not to changes in oocyte development. Also, the study indicates that the hepatopancreas is involved in the metabolism of ecdysteroids related to the moulting cycle but may also be involved in ecdysteroid metabolism during oocyte development. Furthermore, the pronounced increase in oocyte ecdysteroids during oocyte development during periods where haemolymph ecdysteroids titre is low, indicates that the oocytes are capable of de novo synthesis of the three ecdysteroids investigated.

Byssogenesis rate and attachment strength of the mussel Mytilus galloprovincialis were investigated in the laboratory considering different body sizes and feeding conditions. Byssal thread secretion was significantly higher in juveniles as compared to larger mussels of approximately 87 mm shell length. Asymptotic number of threads attached was obtained from approximately 72 hours onwards within a range of 42–46 and 27–31 for juveniles and larger experimental mussels, respectively (P < 0.05 ANOVA). Absorption efficiency values of control fed individuals dropped significantly from 0.78 in juveniles to 0.70 in larger mussels (P < 0.001 ANOVA) which pointed out energetic constraints of mussels with regard to their size and its probable effect on byssus secretion rates. Attachment force was 2.8 times higher in larger mussels than in juveniles (2.21 versus 0.78 N for both sizes, respectively; P < 0.001 ANOVA) which in turn followed the same order of magnitude than differences in the thread's thickness values of both experimental mussel sizes. Tenacity followed a reverse pattern with juveniles presenting two-fold higher values than larger mussels (P < 0.001 ANOVA) based on a lower increment of attachment force (x2.8) as compared to shell area (x6) for the comparison larger versus juvenile mussel size, which in turn might suggest that larger specimens secreted weaker threads. When animals were maintained unfed for a week, a significant drop in both byssus secretion and attachment force were observed in juveniles but was not the case for larger mussels most likely as a consequence of a relatively short period of maintenance under food availability stress for the latter individuals that showed significantly higher initial condition and/or energetic store values. Accordingly, the use of energetic reserves in juveniles kept unfed for a week together with a significant drop in byssus secretion and attachment force might suggest a link, i.e. transfer of energy between soft tissues and byssus under stress. Quantitative values of byssal threads, based on the significance of the byssus versus attachment force relationship, together with its morphometric value, i.e. thread's thickness, represented a primary mechanism to explain variability in attachment strength of M. galloprovincialis of the different body sizes studied here.

The spatial heterogeneity of epifauna on a Modiolus modiolus reef off north-west Wales was investigated using divers. The community associated with these horse mussels was similar to that described previously from Loch Creran and the north basin of Strangford Lough. Some differences in epifauna may be attributable to the less sheltered nature of the site. Modiolus modiolus numbers and the associated epifaunal community were significantly different between ridge and trough sub-habitats. Troughs can be considered ‘reduced’ ridge communities whereas ridges have high densities of horse mussels and certain sessile taxa were correlated with their abundance. Modiolus modiolus aggregation as a competitive response to the feeding environment, enhanced food availability on ridges and sediment deposition amongst mussel clumps may start to explain the undulating bed-form. Patchiness in community composition and periodic cover by ophuroids has implications when considering the monitoring of the horse mussel community. Stratified, in situ recording of the highly populated ridges could improve the statistical sensitivity of monitoring horse mussel reefs whilst simultaneously focusing on the more sensitive indicators of fishing threats.

The composition of fatty acids was studied in the mussels collected in the Mar Grande of Taranto (northern Ionian Sea) during the four seasons. Micro-, nano- and picophytoplankton abundance, biomass and composition have been also evaluated. Fatty acids compositions were investigated for lipid biomarkers to establish the contribution of phytoplankton to the mussel diet. Saturated (SAFA) and monounsaturated fatty acids (MUFA) were the most abundant components, followed by polyunsaturated fatty acids (PUFA). The seasonal variations in the SAFAs, MUFAs and PUFAs were not significantly different during the whole study period (ANOVA, P < 0.05). The most abundant identified FAs were 16:0 (27.51–33.80% of total FAs), 14:1 (3.35–9.91% of total FAs), 18:1n9 (2.92–8.87%), 16:1 n7 (4.53– 7.61%) and 24:1n9 (0.43–8.84%). The most important PUFAs were 22:2 (2.35–3.48% of total FAs) and also 18:2n-6 (1.66–2.61%). PUFAs were characterized by low percentages of n3 and n6 FAs. Analysis of specific FA markers for diatoms (16:1n7, 20:5n3), phytoflagellates and dinoflagellates (16:0, 18:4n3) showed a negligible contribution of phytoplankton to the mussel diet.

Imposex, the development of male sexual organs in female gastropods, is mainly induced by organotin compounds used as biocides in antifouling paints. As part of our continued efforts to report the occurrence of imposex gastropods along the coast of mainland China, this study investigates the imposex prevalence in Mauritia arabica (Mesogastropod: Cypraeidae). A total of 529 adults were collected from 11 sites in south-eastern China between March 2001 and June 2005. Of these, 303 were females and 226 were males. Imposex is classified into six stages representing the sequence from the initial appearance of the seminal groove or small penis (S1) to the point when this duct blocks the pallial oviduct and aborted egg capsules appear (S6). All six stages of imposex were found in M. arabica with three different types (a, b and c) of expression in stages 1 and 3, two types (a and b) in stage 2, and one type in stages 4, 5, and 6. Imposex development was also measured by various indices such as the vas deferens sequence index (VDS), female penis length (FPL), percentage of affected females (%I), the relative penis length (RPL), and relative penis size (RPS—the cubed form of RPL). Imposex individuals were found in all 11 sites with %I ranged from 26% to 100%. Excluding the data from site 3 (with only one female and one male), VDS scores ranged from 1.05 to 4.07, with an average of 2.86, and the RPL ranged from 0.9 to 56.8. High correlations were observed among VDS, FPL, %I, RPL, and the RPS. Our findings suggest that M. arabica is an ideal bioindicator for organotin pollution along the south-eastern coast of China, and can be used in conjunction with the rock shell, Thais clavigera, a well-established bioindicator of tributyltin and triphenyltin contamination. To our knowledge, this is the first detailed report of imposex in M. arabica.

Hydroids symbiotic with octocorals in the Bunaken Marine Park and in the Lembeh Strait (North Sulawesi, Indonesia) were studied. Four species, Hydrichthella epigorgia, Ralpharia neira, Pteroclava krempfi and Zanclea timida sp. nov. were recorded and are described. The new species Z. timida is the only one of the genus associated with an octocoral. It is characterized by a naked hydrorhiza producing nematocyst knobs and by polyps which are able to retract into their own rigid, cup-shaped, basal region. The relationship between epibiontic hydroids and their octocoral hosts affects the morphology of both partners. The hydrorhiza of Hydrichthella epigorgia is naked when associated with Anthoplexaura dimorpha, but perisarc-covered when growing on other gorgonian host species. Vice versa, the hydroid is also able to affect the host morphology: Ralpharia neira induces Ellisella sp. to develop new branches, with the inner skeleton enveloping the hydroid stem.

An expanded description of a little-known arctic species Montacuta spitzbergensis from the Sea of Okhotsk with new data on its morphology, ecology and geographical distribution is given. This is the first record of M. spitzbergensis from the north-western Pacific. It differs from other species of Montacuta in its large (to 8.4 mm), elongate–ovate, thick shell with wide, slightly curved hinge plate, wide, short, and shallow resilifer, and weakly developed external ligament. This species occurs in the Arctic Ocean (Spitsbergen, Barents, Kara, Laptev and Chukchi Seas) and the Pacific Ocean (Sea of Okhotsk) at depths from 9 to 232 m at a bottom temperature from −1.62°C to +2.50°C. The hinge structure of the type species of the genera Montacuta and Tellimya is also discussed.

The metazoan parasite community of Cerastoderma edule was studied in the southern geographical range of the host (the coastal lagoon Merja Zerga, Morocco). A total of 11 metazoan species was found in cockles. Nine of these were trematodes using cockles as either first intermediate host (three species) or second intermediate host (six species). In addition, two other endo-metazoan species (Pinnotheres pisum and Paravortex cardii) were recorded from cockles in the studied lagoon. All the observed metazoans in cockles from Merja Zerga have previously been recorded at sites north of Africa.

Up to 10% of the cockles in the studied size-groups were first intermediate hosts to castrating parasites (Gymnophallus choledochus, Labratrema minimus and Monorchis parvus). Among trematodes having metacercariae in cockles (second intermediate host) Meiogymnophallus minutus was the most widespread as it was observed in all cockles from all the examined habitats in the lagoon and it occurred in record high intensities. Different sub-communities of the trematode fauna using cockles as second intermediate host could be identified (subtidal vs intertidal associations).

The richness and species composition of the macroparasite community in cockles from Morocco are discussed in relation to patterns seen in cockles from other sites along their geographical range. Migratory fish and waterbirds (final hosts) are generally responsible for the large scale spread (latitudinal spread) of trematodes. However, the distributional patterns of involved intermediate hosts in the life-cycles of the different trematode species in cockles are determining the richness and species composition patterns seen in cockles at shallow water sites along the east Atlantic shoreline.

Individual identification using Hi8 video images was tested on the population of estuarine dolphins, Sotalia guianensis that inhabit the Cananéia estuary, south-eastern Brazil. Between June 2001 and August 2002, 25 different dolphins were identified by nicks on the dorsal fin (80%) and by the association of cuts and scratches on the dorsal fin and the body's dorsal region (20%). The existent marks were used to create an identification key to ease the matching between dolphins. The animals were present on 100% of the sampled days, and some of them were repeatedly registered at the same sector in the area, suggesting that although they occupy an extensive area, they use it in an intended way. When compared to researches that used photographs to identify cetaceans, the video images showed some loss of information, nevertheless the analysis could be done without impairment of results, therefore this method proved to be efficient.

Deep-sea organisms are generally considered to be restricted to the great ocean depths, unable to enter shallower habitats except perhaps at the isothermic polar latitudes, due to physiological constraints, or more intense biotic interactions. Wood-boring bivalves of Xylophaga, however, are here shown to be exceptional. A clade, formally recognized by Turner in 2002, united by the derived characters of a complex mesoplax and a truncated excurrent siphon, papillose incurrent siphon with a longitudinal dorsal trough bordered by lappets, and often carrying white or glass-like granules, occurs at significantly shallower and warmer depths than do other species of the genus. Here, description of the new species X. multichela from 106 m depth off the Pacific coast of Guatemala illustrates the characters that unite the clade. Because wood-boring bivalves face intense competition and high levels of predation at depths of 2200 to 3250 m, they may not perceive biotic interactions at shallower depths to be dramatically more intense. In addition, members of this group are hypothesized to tolerate reduced oxygen availability, a requisite if animals are to occur in warm waters.

A total of 104 Semirossia patagonica were collected all over the Patagonian shelf between the depths of 47 and 295 m. Mature female size varied from 10 to 35 mm ML, mature male size was 16–32 mm. Potential fecundity ranged between 527–766 eggs in pre-spawning females, ripe egg size was 3.4–5.0 mm. The oviduct capacity probably was no more than 30 eggs. The maximum number of spermatophores in males was 229. Males transfer 2–19 spermatophores to females during copulation. The ovulation pattern is asynchronous, individual spawning is continuous. Reproduction occurs all year round. Semirossia patagonica is a south-west Atlantic ecological sibling of north-east Atlantic bobtail squids Sepiola spp. and Sepietta spp.