Sampling data on abiotic parameters and benthic communities in the northern lagoon of Tunis were obtained seasonally from November 1999 to November 2000. Abiotic parameters studied revealed evident improvement of water quality compared with previous. Indeed, management has re-established a tidal marine influence (Gulf of Tunis), induced a remarkable change in physico-chemical parameters and as a consequence, a regulation of the lagoon environmental quality. A total of 90 species of benthic macroinvertebrates, belonging to seven different taxa were collected in the northern lagoon of Tunis. A comparison of ecological indices indicate significant variations in the spatial and seasonal distribution and structure of the benthic community and reflect changes that might be related to open marine water and climatic influences as well as effects of discharge of the neighbouring city. Generally, the lagoon macrobenthic community appeared to be better structured, richer and more diverse than the one described before sanitation works began. However, significant disturbance of the benthic communities is detected in the south-eastern lagoon zone (C) and is dominated by disturbance indicator species. In contrast, the Station A2 which is sufficiently influenced by marine currents, is dominated by species of marine affinity and indicates an undisturbed zone. Multivariate analysis indicates heterogeneity in the benthic community structure between stations and suggests that the most significant variations of abundance occur in the groups: Anthozoa, Placophora, Cephalopoda, Ascidia and Echinodermata. The results of correspondence analysis also testify to a gradational distribution of benthic species in relation to hydrological and edaphic (organic matter) factors.

The composition and structure of a molluscan assemblage was studied in a deep subtidal eelgrass bed located in southern Spain before and after the eelgrass decline experienced during 2005 and 2006 due to illegal trawling by fishermen. Sampling was undertaken in summer 2004 (with eelgrass) and summer 2007 (without eelgrass) in an extensive eelgrass bed located in Cañuelo Bay (12–14 m depth) and in the same area once the eelgrass bed disappeared. Eelgrass was completely absent in those samples of summer 2007 and an increase of the organic content and mud was registered in the sediment between 2004 and 2007. The density and the richness of molluscan species decreased significantly in summer 2007, especially for epifaunal gastropods associated with the leaf and sediment stratum. Some species disappeared completely in summer 2007 such as the dominant periphyton grazers Jujubinus striatus and Rissoa spp., the egg feeder Mitrella minor and the seagrass feeder Smaragdia viridis as well as the infaunal bivalve Solemya togata. Other species increased their densities such as the carnivores Cylichna crossei or C. cylindracea as well as the bivalve Nucula nitidosa. Some dominant infaunal species, such as Chamelea gallina, Spisula subtruncata or Tellina fabula did not significantly change their densities. The composition and structure of the assemblages in summer 2004 and summer 2007 was significantly different according to the Bray–Curtis similarity index using qualitative and quantitative data and considering the entire assemblage (epifaunal and infaunal species) or only the infaunal species. The registered changes in the molluscan assemblage may have produced cascade effects in higher trophic levels because molluscs generally represent an important food source for some decapods and fish. Urgent conservation measures are needed for protecting the remaining fragmented eelgrass beds of southern Spain from further illegal fisheries activities and other types of human impacts (e.g. sand extraction and coastal infrastructures), because they support the most diverse faunistic communities for eelgrass beds in Europe due to their bathymetry and geographical location.

The life cycle of the South African gnathiid isopod, Gnathia pilosus, was studied using the common east coast tidal pool fish, Scartella emarginata and Antennablennius bifilum as hosts. Laboratory studies observing the feeding ecology of these temporary ectoparasites determined that the second and third unfed larval stages (zuphea larvae 2 and 3) took an average of 3 hours 52 minutes and 4 hours 19 minutes to feed respectively. After feeding, the second stage fed larvae (praniza 2) took 35 days to moult into the third zuphea form. Male and female praniza 3 larvae could be discerned before their final moults into adults which took place approximately 42 and 48 days respectively after their blood meals. Fertilization occurred within 24 hours after the female had completed her moult. It was thus estimated that the complete life cycle from the first larval stage to adult took between 134 to 140 days in water temperatures ranging between 20°C and 25°C. The length for this life cycle is unexpectedly long for gnathiids living in subtropical waters and may indicate that water temperature is not always the main factor in determining the duration of gnathiid life cycles.

The capture of crabs of the genus Callinectes is one of the oldest extractive activities practised by waterside communities, due to the abundance of brachyurans along the Brazilian coast. The present paper aimed to provide basic information on the population biology of C. sapidus and C. danae during the period of December 2003 to November 2004, in Babitonga Bay, Joinville, Santa Catarina. The size of the first maturation of C. danae was estimated as 7.1 cm in total carapace width for females, and as 8.6 cm for males. Fecundity of the 20 females of C. danae with carapace width from 7.0 to 11.0 cm varied from 618,667 to 811,267 eggs. Fecundity of C. sapidus was higher, with a median of 978,000 eggs per female, but carapace widths in this species were also larger, with the highest frequency of females attaining 19.01 cm on average. In both species, a tendency was observed for the egg mass to increase with size of females. The capture per unit of effort presented the lowest values in summer, while the largest values occurred from March, August and November. A total of 80 males and 117 females of C. sapidus were captured in the four collecting areas, with the largest abundances in Area III (45.18%), followed by Areas II, IV and I. The size of the first maturation of C. sapidus was estimated as 10.2 cm for females and as 9.0 cm for males. Fishing effort was in relative equilibrium for adult stock (males = 58.75% and females = 52.99%) and juveniles (males = 41.25% and females = 47.01%). The largest monthly rates of biomass of C. sapidus occurred from April to November, with a peak of capture in August, without significant differences in the participation of males and females.

The Magharees fishery (Brandon and Tralee Bays in south-west Ireland) is 495 km2 in extent, the majority of this area ≤20 m in depth. Since 1981 it has been occupied by a directed spider crab fishery yielding in some years all of the national catch of Maja brachydactyla. Maximum recorded landings were 336 t in 1999 and effort has numbered up to 10,000 pots annually. Increasing fishing capacity and declining opportunities have accentuated fishing effort on spider crab. This paper describes a catch census undertaken in the fishing season of March to August inclusive, 2000–2007 and a mark–recapture experiment, 2005–2007. A method of ageing the adult moult by attributing a chronology to the rate of erosion of the claw on the dactyl is introduced. Males migrated longer distances, moved into the fishery on a wider trajectory and demonstrated greater wear on the claw than females. Recapture rate of males was twice that of females. The conduct of the fishery changed in its 26 years in existence. Landings became more concentrated in the earlier months of the year and the recent summer fishery was characterized by fewer male captures. Larger males were quickly removed and none >140 mm carapace length survived in the fishery longer than one year.

Nursery areas of European sea bass (Dicentrarchus labrax, L.) were investigated from spring 2005 to summer 2006 in areas along the French Mediterranean coast of the Gulf of Lion. Nurseries were identified by the presence of settling individuals of sea bass and young juveniles. These nurseries represent different types of sheltered shallow habitats, both natural such as coastal lagoons, estuaries, and artificial such as marinas. Settlement occurred from April to June during both years. The number of settling individuals varied between sites from just a few individuals to several thousand. In one given site, settlement also varied between 2005 and 2006. The size distribution of sampled individuals revealed that several pulses arrived in each nursery. At this stage, sea bass already exhibited a strong orientation capacity but a limited swimming ability. The magnitude of sea bass settlement in marinas requires better environmental management of such artificial areas.

The diet of blue runner Caranx crysos (Carangidae) in the Gulf of Gabès (Tunisia, Mediterranean) is described from analysis of stomach contents (N = 1668 fish). The majority of samples were obtained from commercial purse seine and gill-net catches. The index of vacuity (%VI) was relatively high (58.7%) and differed significantly across months. Blue runner is an opportunistic predator that consumes mostly pelagic organisms, with benthic prey representing only a small proportion of the diet. The diet was quantified using the frequency of occurrence (%F), numerical abundance (%N), weight (%W) and the index of relative importance (IRI and %IRI) for each prey taxa.

The most important prey categories were teleosts (%IRI = 83.4) and crustaceans (%IRI = 16.6), with molluscs only observed occasionally (%IRI < 0.1). Fish were also the dominant food items in both terms of weight (89.60%) and frequency of occurrence (82.44%). In terms of numerical abundance, crustaceans were the most abundant prey (78.07%). Ontogenetic and seasonal differences in the diet were observed, although there was no difference between the diets of males and females.

The commensal (and possibly mutualistic) symbiosis between the marine chironomid, Halocladius variabilis, and brown algal epiphytes of Fucus vesiculosus and Ascophyllum nodosum is described for the first time from Europe, based on field studies from the White Sea, Russia. While the primary host, Elachista fucicola, and the secondary host, A. nodosum, are the same as in eastern Canada where the symbiosis was first described, White Sea populations have a wider range of primary hosts that include Pylaiella littoralis and Dictyosiphon foeniculaceus. About 64% of E. fucicola thalli on A. nodosum in the low intertidal zone were colonized. Significantly lower frequencies were found on E. fucicola when the latter was epiphytic on F. vesiculosus at the same tidal height or on either secondary host when they were in the subtidal zone. For a given tidal height, or secondary host, frequency of H. variabilis was reduced on P. littoralis and further reduced on D. foeniculaceus. We suggest that subtidal populations are colonized by dispersal of larvae from the intertidal zone on to suitable substrata, and that there is limited potential for these individuals to reach the intertidal zone as adults for reproduction.

Novel predator–prey interactions are becoming increasingly relevant to investigate in the context of current geographical range expansions and biological invasions. This study describes a vigorous attack by a muricid whelk, Thais gradata on a mud-inhabiting mytilid mussel, Musculista senhousia, following new colonization of the mussel in the Brunei estuarine system (Borneo, South-East Asia). This represents only the second reported attack by a gastropod on this globally important invasive mussel species, and the first such attack in its native environment. Whelks migrated from their typical hard surface habitat and barnacle feeding to the sediment, where they aggregated and fed on the mussels. Field data suggest no selection by the whelks of the part of the mussel bed colonized or of the prey size attacked (median shell length = 21 mm). In addition to forming feeding aggregations, the whelks formed non-feeding resting aggregations off the mussel bed (sometimes of more than 80 individuals). These apparently facilitated synchronized mating and consequently the formation of large communal nests of egg capsules (involving approximately 3500 contributing females). During the investigation, the newly-formed mussel colony underwent mass mortality, and the whelks either redistributed on the sediment or returned to feeding on barnacles. The population-level response by the whelks described here maximizes energy transfer from prey resource to whelk propagation. In addition to the whelk's generality of habitat use and feeding behaviour, this is likely to contribute to sustaining populations in a system where prey abundance and distribution is limited by highly variable and extreme physicochemical conditions.

Digenean trematodes are omnipresent in the cockle Cerastoderma edule, a common coastal bivalve of (semi-)sheltered north-eastern Atlantic coasts. They can use their host as a second intermediate host where they remain in a relatively latent stage as metacercariae. Cockle population dynamics and trematode parasite load were monitored for two years in two sites, Arcachon (France) and Merja Zerga (Morocco) for the cockle cohort of 2005. Individual growth was slightly higher at Arcachon than at Merja Zerga (Von Bertalanffy parameters: K = 1.5 yr−1 in both sites but L∞ = 31.2 mm at Merja Zerga against 38.3 mm at Arcachon). Production during cockle life was twice as high at Merja Zerga (48.5 compared to 22.2 gDW.m−2 at Arcachon). Elimination compensated production at Merja Zerga while elimination was low at Arcachon (8.1 gDW.m−2) due to sediment dynamics which concentrated cockles within the sampling area. P/B was similar in both sites (2.4–2.6 yr−1) while E/B was higher at Merja Zerga (2.2 yr−1 versus 1.0 yr−1). Trematode communities were similar in both sites in terms of species and abundance. During the cockle cohort lifespan, there were 3 to 5 events in the parasite abundance survey that suggested parasite-dependent mortality. At Merja Zerga, trematodes metacercariae did not affect P/B (2.4 yr−1) but increased E/B (+14%). At Arcachon, they also had no effect on P/B (2.6 yr−1) but on the contrary increased E/B (+20%). The threshold of metacercariae abundance beyond which cockles are affected was lower for Echinostomatid trematodes at Merja Zerga, suggesting an interaction with other factors such as temperature which is higher at the southern limit of cockle distribution.

Sampling of commercial fisheries bycatch in south-western Australia has yielded a second and different form of hermaphrodite of the Port Jackson shark Heterodontus portusjacksoni. Its total length (706 mm) and weight (2740 g) fall within the range of those of mature males, but below those of mature females. The left clasper was similar to that of normal mature males, whereas the right clasper was far smaller, had a poorly-developed rhipidion groove and lacked a spur. The body cavity possessed a testis on the left, an ovotestis on the right, and contained sperm ducts, oviducal glands and uteri on both sides. As with normal mature males, the testis and the testicular component of the ovotestis contained germ cells in various stages of spermatogenesis, including late stage spermatids. The ovarian component of the ovotestis contained 14 follicles that were larger (5–9 mm diameter) than those of normal females of similar size, which were immature, but far smaller than those of normal mature females. Six of those follicles were atretic. The widths of the left and right oviducal glands and uteri were far greater than those of normal females of similar size, but similar to those of normal mature females. Thus, although gonadal maturation had progressed further in the testis and the testicular component of the ovotestis than in the ovarian component of the ovotestis, the oviducal glands and the uteri of the hermaphrodite were of similar size to those of normal mature females and were far better developed than those of normal females of similar length, which are immature.

Cardiac performance of the Chinese black sleeper (Bostrichthys sinensis) was examined at early stages of development (the heartbeat, blood circulation and newly hatched larval stages) under different hypoxic oxygen concentrations. Exposure of the embryos at 25°C to 0.2 mg/l dissolved oxygen (DO) indicated periodic heartbeat at both the heartbeat stage and the blood circulation stage, but it started sooner after exposure at the blood circulation stage than at the heartbeat stage. With the appearance of the gill slits, the tolerance of the newly hatched larvae to hypoxia was improved. The larvae did not display periodic heartbeat at 0.2 mg/L DO, but periodic heartbeat occurred at 0.1 mg/L DO and 0.02 mg/L DO after 23.3±6.2 minutes and 13.2±3.4 minutes of exposure. With exposure of the embryos to hypoxia, the occurrence of periodic heartbeat of excised embryos was earlier than that of whole egg embryos at both the blood circulation and heartbeat stages. These results indicated that the tolerance of embryos to hypoxia decreased with the progress of embryogenesis and suggested that the perivitelline liquid can protect the embryos by conserving oxygen. In this study, we also found that a breakdance performance (an arrhythmic heart beat) occurred in the newly hatched larvae at 0.02 mg/l DO. The breakdance performance lasted about 10 minutes, and then the heartbeat became normal.

Six new marine species of the testate amoebid genus Paulinella are described using light and electron microscopic observations of material from Canada's Pacific Ocean coastal waters. In order of test (shell) size, from smallest to largest, the following new species are proposed: P. carsoni sp. nov., P. agassizi sp. nov., P. suzukii sp. nov., P. lauterborni sp. nov., P. multipora sp. nov. and P. gigantica sp. nov. Included in this survey are new observations on P. indentata Hannah, Rogerson & Anderson, from Canadian Pacific Ocean locations, but previously known only from Scottish coastal waters, and the common brackish/freshwater species P. chromatophora, from Ontario (Canada). These new discoveries more than double the number of previously known species of Paulinella, a genus significant for its role as a secondary producer in marine benthic ecosystems and for the possible role of its type species (P. chromatophora) as a model system for the endosymbiosis hypothesis of the evolution of chloroplast-bearing organisms.

Sphaerosyllis sandrae sp. nov. (Annelida: Polychaeta: Syllidae) is described as a new species from shallow sandy bottoms off Guanahacabibes Biosphere Reserve (Cuba). Thirteen more syllid species belonging to nine genera (Exogone, Myrianida, Opisthosyllis, Parexogone, Plakosyllis, Salvatoria, Syllides, Sphaerosyllis and Syllis) have been found from algal and sand bottom samples from the same area; four species that belong to the genera Myrianida, Syllides and Parexogone are only identified at the generic level.

Dasybranchetus pacifica, collected in Concepcion Bay, Baja California Sur, Gulf of California, is described as a new species. In addition, the type species of the genus, Dasybranchetus fauveli Monro, 1931, is redescribed based on type material. The new species differs from D. fauveli in the absence of branchiae, the begining of the mid-dorsal lobe from chaetiger 2 instead of chaetiger 9, abdominal segments with well-developed neuropodial lobes, and hooded hooks with a main fang and three rows of subapical teeth in the following arrangement: 4 teeth in the basal line, 3 in the middle line, and 2 in the apical line.

In studies carried out off the north-eastern and south-eastern coast of Brazil, three species of Prosphaerosyllis were found: P. isabellae, which was already recorded for Brazilian waters; P. xarifae, a newly recorded species for the area; and P. brachycephala sp. nov., a new to science species. Prosphaerosyllis brachycephala sp. nov., is characterized by having swollen anterior part of the body, prostomium retractable within the peristomium and anterior segments, short antennae, short peristomial and dorsal cirri, and falcigers with short, unidentate blades throughout. All these species are herein described and compared to the most similar congeners.

Pionosyllis Malmgren, 1867 is revised based on a cladistic analysis of the 41 species considered herein as valid, two newly described species in this paper (Basidiosyllis victoriae and Opisthodonta russelli), 11 species from other genera actually belonging, or related to, Pionosyllis, and 13 syllid species from different subfamilies. The phylogenetic analysis is based on 55 characters; a strict consensus of 1200 equally parsimonious trees (length = 314 steps) was obtained. The clades containing species usually included within Pionosyllis are newly named within the frame of a new Linnean classification of the group (except for one, belonging to another subfamily). The diagnosis of Pionosyllis is emended, and five new genera are proposed: Synmerosyllis, Basidiosyllis, Westheidesyllis, Perkinsyllis and Brevicirrosyllis. Paraehlersia San Martín, 2003, proved to be closely related to Pionosyllis. Seven species are transferred to Opisthodonta Langerhans, 1879, here emended, and three transferred to Nudisyllis Knox & Cameron, 1970 (according to San Martín & Hutchings, 2006). Opisthodonta uraga (Imajima, 1966) comb. nov. and Perkinsyllis longisetosa comb. nov. are redescribed. Pionosyllis compacta Malmgren, 1867, P. stylifera Ehlers, 1913, P. gigantea Moore, 1908, P. enigmatica (Wesenberg-Lund, 1950), and Nudisyllis magnidens (Day, 1953) comb. nov., are redescribed. Pionosyllis marquesensis Monro, 1939 and P. procera Hartman, 1965 likely belong to the Syllinae, thus they are not treated in the taxonomic account.

Three new species of Iberian cheilostomate bryozoans are described from material held in our own collection as well as in the bryozoan collection in the Museo Nacional de Ciencias Naturales, Madrid. Chaperiopsis hirsuta sp. nov., from the Mediterranean, is the second species of this genus in European waters. Metroperiella gay sp. nov. and Schizoporella artabra sp. nov. are described from material collected in Galicia (north-western Spain).

A new genus and two new species of Mollusca Solenogastres belonging to the family Simrothiellidae are described here: Spiomenia pusilla sp. nov. and Adoryherpia serrata gen. et sp. nov., collected from muddy sediment during the expedition DIVA 1 Me48/1 carried out in the Abyssal Angola Basin, at depths from 5100 to 5500 m.