During a survey of the marine meiobenthos in a predominantly muddy area, 40 km south of Venice (northern Adriatic Sea, Italy), 11 species of gastrotrichs were recorded. Gastrotrichs were found in 11 out of the 16 investigated stations, with densities (mean ± standard deviation) ranging from 0.6 ± 0.5 to 97.7 ± 71.2 ind./10 cm2. The community was dominated by Musellifer profundus, which made up 24.5% of the entire gastrotrich assemblage and reached in a single station the abundance peak of 18.3 ind./10 cm2. The finding bears relevance to the biogeography and ecology of several species. The presence of numerous specimens of the rare M. profundus allowed new insights into the arrangement and functioning of the hermaphroditic sexual apparatus in this phylogenetically important genus, for which such data are scanty. The new information will certainly be useful in evolutionary studies aimed at reconstructing the phylogenetic relationships within Gastrotricha, while offering at the same time additional morphological traits to be used in reliable species identification. Although only three species of Musellifer have been described so far, there are several others awaiting a formal affiliation, a task that will benefit from this new information.

The occurrence of pinnotherid crab Arcotheres tivelae in the bivalve mollusc Amiantis umbonella was investigated for one year on the Bandar Abbas coast (Persian Gulf, Iran). Specimens of A. umbonella were collected monthly from two transects from April 2007 to March 2008 and were investigated for presence of the Arcotheres tivelae. Infestation frequency of A. tivelae was 9.18% in a sample of 893 clams. From a total of 89 specimens of crabs, only eight were male. They were observed in late February and early March, all of them but one in association with female crabs. There was no significant difference between the sexes of the infested clams that pea crabs choose as a host. The mean carapace width of the crab A. tivelae was 7.7 ± 1.7 mm and the mean length of the Amiantis umbonella was 39.84 ± 8.93 mm. Clams in the mid and low tidal zones were more infested. There was no significant relationship between clam length–crab width (R2 = 0.28). The mean fecundity of crabs was 2517 ± 864 eggs. Infection caused a reduction of flesh weight of clams. There was no significant correlation between the frequency of crabs' occurrence and the temporal variability of water temperature, salinity, dissolved oxygen and pH in different months. This study provides the first report of the distribution of pea crabs A. tivelae in A. umbonella, a new clam host record in Iran.

Size at morphological sexual maturity, sex-ratio, and the seasonal variation in abundance of the shrimp Artemesia longinaris Bate, 1888 were assessed off Pinheira Beach, Palhoça, Santa Catarina southern Brazil. Shrimp were collected monthly from November 2003 through to October 2004, in two areas that are customarily used by local traditional fishermen (27°52′–27°51′S and 48°33′–48°29′W). Of the total of 1099 specimens measured, 23.93% were males and 76.07% females. Mean size at first maturity (LM50) was estimated as 56.38 mm total length (TL) for males, and 70.34 mm TL for females. Females were significantly larger than males. Abundance of juveniles varied seasonally. A high predominance of juveniles in the areas sampled occurred in winter for both sexes, and in spring for females. In the summer and autumn, we observed a decrease in juveniles in both areas, mainly, area II. We suggest that the differential migration pattern of sexes during the reproductive cycle was the principal reason for the larger catch of females. The classical paradigm of continuous reproduction at lower latitude, with increased seasonality of the breeding period at higher latitudes, seems to apply to this species.

Over a 52-month period beginning in May 2004 and concluding in August/September 2008, and coinciding with the period over which tributyltin was banned as a ship anti-foulant globally, a population of the dogwhelk, Nucella lapillus on the south-eastern coast of England, was studied for changes in population size and structure, reproduction and feeding behaviour. During the study period, the size of the N. lapillus population grew from ~25 individuals to >500, i.e. a 20-fold increase, and recovery from imposex was total. Significant changes in feeding behaviour were also reported. For example, peaks in N. lapillus predation were recorded over the winter months, but as population size increased, this temporal seasonality was masked due to the growing numbers of juveniles feeding on smaller and smaller individuals of Mytilus galloprovincialis (as opposed to barnacles) as the study progressed. Similarly, with freedom from imposex, the numbers of failed drilling attempts declined and numbers of prey with more than one drill hole increased as the incidence of kleptoparasitism increased. Predated M. galloprovincialis were also increasingly attacked in the antero- and postero-dorsal quadrants of their shells as the study progressed. Contrary to expectations, only a slightly positive relationship between predator and prey sizes was recorded overall however, suggesting that beyond a shell height of ~13 mm, when the transition from barnacle to mussel feeding occurs, M. galloprovincialis individuals of virtually any size are preyed upon by N. lapillus.

Morphogenetic events during the division of the marine ciliate, Euplotes vannus (Müller, 1786) Diesing, 1850 were investigated using protargol impregnation: (1) the opisthe's oral primordium develops de novo in a subsurface pouch above the marginal cirri; (2) the cirral anlagen for the frontal, ventral and transverse cirri in both dividers develop separately on the surface epi-apokinetally, cirrus I/1 and marginal anlagen for daughter cells are formed de novo separately; (3) the dorsal kinety anlagen occur in a non-typical primary pattern within the parental structures at mid-body, of which the 3 right-most ones produce the 3 caudal cirri for the proter; and (4) the opisthe acquires 2 caudal cirri from the end of the right-most 2 kineties. Based on the data available, the reasons for the variation in the number of caudal cirri in E. vannus are discussed.

Several Synalpheus species have been reported as hosts of bopyrid parasites; however, the impact of infestation on egg production is still unknown. Therefore, the present work studied reproductive aspects and the effect of parasitism on fecundity of the alpheid shrimp Synalpheus yano from Bocas del Toro, Caribbean coast of Panama. Un-infested females (N = 84) ranging from 3.7 to 9.6 mm carapace length, produced between 5 and 246 eggs (average: 98±64.6), and egg number increased significantly with female size. The eggs were relatively large (0.6–1.3 mm in diameter), but within the range of other Synalpheus species, and egg size did not differ significantly between un-infested and infested females. Despite these large eggs, the morphological characteristics of hatching larvae indicate a planktotrophic development. During the incubation period, the egg volume increased from 0.100 to 0.218 mm3, representing an overall increase of 118%. A total of 18 females (16% of all ovigerous individuals) were infested, and the occurrence of parasitic infestation was more pronounced in larger females. Infested females ranging from 4.6 to 9.4 mm carapace length, produced between 22 and 166 eggs (average: 81±44.4). Egg-bearing females infested by parasitic bopyrids carried on average 41% fewer eggs than similar-sized females without parasites. The co-occurrence of parasites and developing eggs, however, indicates that the bopyrid parasite does not necessarily castrate its host. Therefore, we encourage more comparative intraspecific studies on egg production in infested and un-infested females to assess the impact of infestation on fecundity in caridean shrimp.

The main objective of this study was to describe the reproductive cycle of the sea urchin Paracentrotus lividus on the Cantabrian coast (north of Spain), and assess its relationship with environmental factors. To achieve this, samples were taken monthly from three localities during 17 months in two different habitats. At least 15 individuals from each location and habitat were collected during each sampling occasion and used for assessments of gonad index and histological sections. The water temperature and the chlorophyll concentration were also measured. The breeding season of P. lividus in Cantabria started in March and continued until September with one or two main spawning periods per year (depending on year and population), the first one in the beginning of spring and the second one in the summer. The most important differences in the gonad cycle were observed among localities, and the smallest among habitats. Temperature, photoperiod and nutritive stage are important factors controlling the gonad cycle. The beginning of spawning in the Cantabrian populations coincides with the spring phytoplankton bloom and the rise in temperature, which may act as environmental triggers.

Amiantis umbonella is distributed throughout the coast of the northern Persian Gulf. This study of 893 clams provides data on reproduction, growth and production for the period April 2007 to March 2008 from two transects along the Bandar Abbas coast. Histological preparations showed six stages of gametogenic development: resting stage (Stage 0), early active (Stage I), late active (Stage II), ripe (Stage III), partially spawned (Stage IV) and spent (Stage V). The specimens were gonochoric and showed synchronized spawning. The reproductive cycle commenced in September and finished in March with one major spawning event in January which correlated with lower sea temperature. Von Bertalanffy growth parameters for the sample were asymptotic length (L∞) = 58–62 mm, growth constant (k) = 0.28–0.29 yr−1 and length zero (t0) = –0.48 –0.47. The mean annual clam abundance, mean biomass and production were 10 individuals. m−2, 5.7 g shell free dry weight (SFDW) m−2 and 0.495 g SFDW m−2 yr−1, respectively.

The reproductive biology of the bathyal hermaphrodite Bathypterois mediterraneus is described based on 348 specimens caught during experimental trawl surveys carried out between 800 and 1600 m depth off the south-eastern Sardinian Sea (central-western Mediterranean). Based on macroscopic and histological gonad analysis and monthly variation of GSI, the female component of the tripodfish shows a reproductive season from March to May. The male component shows, instead, a longer spawning period probably guaranteeing continuous spermatogenesis at any time of year. The oocyte size–frequency distributions in mature component indicated that the species exhibits a synchronous-group and monocyclic ovary characterized by deposition in a single batch of eggs per year (total spawner). The species has a late size at first maturity (L50) of 119 mm standard length (SL); the smallest mature specimen was 110 mm SL.

The populations of Buccinanops monilifer (Gastropoda: Nassariidae) from two different sites, Mar del Plata (Buenos Aires province) and a close non-polluted locality (Mar Chiquita), are compared in their imposex indices and reproductive parameters. In Mar del Plata, a beach nourishment (sand filling) remobilized sediment from the harbour area during 1999; our results show high imposex percentage and an increase in relative penis size index during and after this beach filling event, in contrast with the Mar Chiquita population that showed nil values during this study. Comparisons of reproductive parameters between both populations showed significantly higher frequency of spawning females and number of egg capsules per female in Mar Chiquita, while female size and number of eggs per capsule did not differ. Females from Mar del Plata that did not succeed in spawning showed higher imposex values than spawning ones. Sex-ratio was not significantly different from 1:1 in any of the sites (although male-biased in Mar del Plata and the opposite in Mar Chiquita). We found no malformations or abnormalities during intracapsular development in the imposexed population. Alternatively, we found evidence that suggests that B. monilifer intracapsular development includes the occurrence of intracapsular embryonic cannibalism of other smaller embryos, which was not previously known in this genus, and that complements adelphophagy (feeding on nurse eggs feeding).

Stenopodidae comprises about 28 species in tropical and subtropical waters around the world, but only two of them in the South Atlantic Ocean (SAO)—Stenopus scutellatus and S. hispidus. Larvae of S. scutellatus were never registered in SAO and those of S. hispidus remain poorly researched. The present study fully describes first to seventh zoea of S. hispidus collected in the plankton of SAO, adjacent to Brazil. In addition, eight larvae of S. scutellatus and two larvae of non-identified Stenopodidea from the same area were also described.

In addition to the spicules typically produced by sponges, about twenty hypercalcified species belonging to both classes Demospongiae and Calcispongiae secrete a massive basal calcareous skeleton composed of calcite or aragonite. Skeletal growth rates and growth mechanisms are still poorly known in those hypercalcified Calcispongiae. In situ calcein staining experimentation on the Mediterranean calcisponge Petrobiona massiliana revealed a mean annual growth rate of the massive skeleton of 236 µm/y (±90). Scanning electron microscopy (SEM) revealed that some spicules are entrapped within the massive skeleton (a solid mass forming apical crests with multidirectional growth axes) during its formation. Whole actines were observed within the massive skeleton of fractured specimens, indicating that they do not dissolve after entrapping. Calcein incorporation bands seen through epifluorescence microscopy and SEM morphological observations of the skeletal surface revealed cone shaped protuberances corresponding to active growth areas. A spatially discontinuous growth was highlighted, but the annual growth rates were similar at the tip of crests and at the bottom of depressions separating them. The skeleton of P. massiliana is composed of magnesium calcite with strontium as the main trace element. Significant differences in skeletal chemistry of specimens collected in different Mediterranean locations revealed a possible temperature dependence of Mg/Ca. Although such temperature signature exists in the massive skeleton of P. massiliana, its use as an accurate environmental recorder is limited by several factors including multidirectional and spatially discontinuous growth.

Age, growth and cost of reproduction were examined for the small near-shore loliginid squid Loliolus noctiluca in Tasmanian waters, near the southern limit of its distribution. The effects of several factors on hatch size were also evaluated by comparing the statolith natal ring size (NR) from individuals collected in different locations, seasons and years. The life cycle of L. noctiluca was less than six months. July-hatched females grew faster than their May-hatched counterparts, indicating a faster growth in winter-hatched compared with autumn-hatched individuals. There was considerable variation in NRs as function of location, season, year and sex, with females displaying NRs considerably larger than males in any location and year. Immature and maturing females displayed poorer body condition than mature counterparts, suggesting that gonad growth does not affect the mantle or fin growth. A good condition was maintained also in spent individuals indicating that L. noctiluca continued to invest in somatic organs throughout the spawning period. A reproductive strategy closer to ‘multiple spawning’, than to ‘single spawning’ was proposed for this species. Loliolus noctiluca was used as a model to explore the possible effects of climate change on near-shore loliginid populations.

The diatom, Phaeodactylum tricornutum is a common inhabitant of inshore waters and can exist in different morphotypes that are thought to be adapted for survival in different habitats. Despite this diatom being widely used for physiological and genetic studies of microalgae, little is known about biochemical or physiological differences between the cell morphotypes. The present study was aimed at comparing differences in the antibacterial properties of the fusiform and oval morphotypes, the dominant cell types found in laboratory cultures of most strains of P. tricornutum. In cultures differing in proportions of fusiform and oval cells, there is a significant and positive correlation between the proportion of cells in the fusiform morphotype and the antibacterial activity of cell extracts. Extracts prepared from cultures enriched for fusiform cells (~76%) show greater antibacterial activity against the Gram-positive bacterium, Staphylococcus aureus, than those prepared from pure (100%) oval cultures. Thus fusiform cells contain greater antibacterial activity per cell compared to the ovals. Gas–liquid chromatographic analyses of the extracts reveal that those from enriched fusiform populations contain significantly greater levels of the free fatty acids, eicosapentaenoic acid (EPA), hexadecatrienoic acid (HTA) and palmitoleic acid (PA) than the pure oval cell cultures. These free fatty acids from P. tricornutum have been previously shown by us to have potent antibacterial activity against S. aureus. Free fatty acids, released from damaged microalgal cells, defend the microalgal population against grazing predators but, here, we suggest that these free fatty acids could also act against pathogenic bacteria in the vicinity of the algae. As cell extracts from the fusiform cells contain greater quantities of these fatty acids, fusiform cells may have greater potential than the ovals for this type of protection.

The family Thorectidae includes 23 valid genera and 130 species, characterized by the presence of laminated fibres and diplodal choanocytye chambers. Currently the genus Thorecta comprises approximately 20 valid species, distributed mainly in the Indo-Pacific. We describe here a new species of Thorecta that is the only valid species of the genus described in the Atlantic Ocean so far. Samples were collected by trawling on board of the RV ‘Astro Garoupa’ in Potiguar Basin, on the northern coast of Rio Grande do Norte State, north-eastern Brazil. Thorecta atlantica sp. nov. is greyish-brown to dark brownish-grey and presents a distinctive globular or clavulate shape, with 1–2 large apical oscules that open to deep atria. It was found between 61 and 160 m depth. A literature survey suggests that many species referred to Thorecta should be relocated to different genera due to absence of diagnostic characters, and that the genus Thorecta should group only 11 species: T. carteri, T. marginalis, T. prima, T. lata, T. farlovi, T. meandrina, T. polygona, T. reticulata, T. tuberculata, T. vasiformis and T. atlantica sp. nov. The tortuous history of the genus is an example of the damage that poorly-described species can cause to classification. Detailed descriptions of fresh material, well illustrated by photographs and including as many characters as possible, are essential tools for the clarification of the systematics of Thorecta in the future.

Two species of Scolelepis were found off the Venezuelan coast, one of these is a new record for this region, and the other is a species new to science: Scolelepis (Scolelepis) lighti Delgado-Blas, 2006, and Scolelepis (S.) andradei sp. nov., respectively. Scolelepis (Scolelepis) lighti was previously known only from the Gulf of Mexico and Florida, but the Venezuelan specimens closely match the original description. Scolelepis (S.) andradei is distinguished by the fusion of the anterior and posterior branchiae to the notopodial lamellae, bidentate notopodial hooded hooks starting from setigers 23–29, and the absence of notopodial hooks.

Four species of the genus Haplosyllis from Indonesia are herein described and illustrated. In Haplosyllis aciculata sp. nov. and Haplosyllis ingensicola sp. nov. the longest midbody cirri exceed body width and posterior parapodia have a single broad, strongly curved acicula, while in Haplosyllis tenhovei sp. nov. and Haplosyllis nicoleae sp. nov. cirri are shorter than body width, and the two or more aciculae are straight or curved. The available information on the ecology and host species is provided.

A new species of the palaemonid shrimp genus Periclimenes, P. cannaphilus, is described from upper bathyal hydrothermal vents of the Bonin-Mariana Arc in the north-western Pacific at depths of 392–456 m. A symbiotic relationship between the new shrimp species and a siboglinid tube worm Lamellibrachia satsuma is suggested by their simultaenuous collection and further observations in situ. Similarities in the morphology and symbiotic association suggest that the new species is closely related to P. thermohydrophilus, also associated with L. satsuma in shallow hydrothermal vent fields in Kagoshima Bay, southern Japan, but differences in the rostral shape, the position of the epigastric tooth on the carapace, and the development of the hepatic tooth on the carapace morphologically differentiate the two species. Phylogenetic analysis based on sequences of the mitochondrial DNA COI gene supports the recognition of two clades corresponding to these two taxa.

Despite the increase in the number of deep-sea studies, little is known about the hadal molluscs. For Brazil, only a few studies have treated the Septibranchia. This contribution is part of an effort to increase the knowledge of this group off the Brazilian coast, although it is focused only on the Campos Basin (22°S), State of Rio de Janeiro. Four species of the family Verticordiidae are recognized here. For Spinosipella tinga Simone & Cunha, 2008, the known depth distribution is extended to 1050 m. For Verticordia woodii Smith, 1885, previously reported from Brazil, the known distribution is extended southwards to the Campos Basin. Verticordia quadrata Smith, 1885, is reported from Brazil for the first time. A previously unknown species, Verticordia ouricuri sp. nov., is described. The presence of small spines, typically with a hexagonal column and a stellate structure at their distal end emerges as an additional taxonomic character for the verticordiids.

Since 1993 Cerithiella danielsseni (Friele, 1877) has been regarded as a variety of C. metula (Lovén, 1846). An argument is made for reinstating C. danielsseni as a valid taxon inhabiting below-zero waters on the slope around the Nordic Seas. This conclusion is based on lack of overlap in shell morphology between specimens found below and above the ecotone where the thermocline meets the slope. Just above the ecotone and also in the Barents Sea north of ~72°N, the shelf species C. metula occurs, but with morphology slightly modified from that of the ‘typical’ form.