The seasonality of sexual reproduction was studied in two Prochloron-bearing ascidians, Trididemnum cyclops and Lissoclinum bistratum, on a subtropical coral reef off Okinawajima Island, Japan. These colonial ascidians had testes and/or eggs/embryos from spring to summer. Embryos with tails occurred in summer. Whereas many photosymbiotic didemnids are thought to be sexually mature throughout the year in the tropics, sexual reproduction of the same species in subtropical waters may be limited to spring and summer. The subtropical winter may be too cold for gonad formation. A histological study of sexually mature colonies showed no Prochloron cells attached to ascidian larvae in the pre-hatch stage.

Population structure of the important commercial brown shrimp, Crangon crangon, was investigated in samples from five UK sites using a multidisciplinary approach based on morphometrics, allozyme electrophoresis and amplified fragment length polymorphism (AFLP). Multivariate analysis of the morphometric data revealed variation in the tail shape of C. crangon from Wansbeck (north-east England), which was found to have longer inner uropod and telson lengths in comparison with all other sites. Linear discriminant analysis was also able to place 86% of the Wansbeck individuals in the correct group. Crangon crangon were screened at two allozyme loci (Gpi and Pgm) revealing higher levels of polymorphism at both loci than previously reported. Allozyme allele frequencies showed evidence of population subdivision between east and west coast UK sites (FST=0.011). Data from three AFLP loci (Cra47, Cra56 and Cra70) confirmed population differentiation (FST=0.083) and combined allozyme and AFLP genetic data identified C. crangon from Wansbeck as different from all other sites. Random genetic drift and selection in populations with restricted gene flow are likely to be the main causes of the differentiation observed. The results do not support an earlier report of six distinct populations based solely on morphometric analysis.

The parasitic copepod, Splanchnotrophus willemi, is recorded infecting the nudibranch Ancula gibbosa for the first time in the UK. Seven out of twenty Ancula gibbosa sampled from Mumbles, Swansea, UK, were found to be infected with S. willemi. Light microscopy was used to investigate the effects of S. willemi on its host. In six hosts the internal damage caused was minimal. However, in one host the damage was extensive resulting in the disintegration of the digestive and reproductive viscera. One other A. gibbosa not parasitized, exhibited similar damage and it was postulated that this animal may have survived infection. In all cases of infection there was never more than one male or one female S. willemi present.

Morphological study of the podia of the suspension feeding Amphiura filiformis and the deposit feeding Amphiura chiajei revealed sensory–secretory complexes in the podial epidermis, consisting of four cells, two secretory and two sensory. Large mucus cells were found in association, but not exclusively, with the sensory–secretory complexes. In A. filiformis, mucus cells stained positively for both acid and neutral mucopolysaccharides, while, in A. chiajei, these cells stained only for acid mucopolysaccharides. The surfaces of the arm podia in A. chiajei were relatively smooth, while the arm podia of A. filiformis bear papillae. The sensory–secretory complexes open through numerous paired pores, with each pair having an intervening cilium. Pores were restricted to the podial tip in A. chiajei, while in A. filiformis they are concentrated on the podial tip and on the papillae. Amphiura chiajei shows very little differentiation of the podia along the length of the arm. In A. filiformis, the distal podia have papillae throughout their entire length, with pores being found on the head region and the papillar tips. Here, the papillae are oriented in such a way (i.e. facing inward towards the ventral arm plate) as to increase the area of the filtering surface of the podium, serviced by the sticky secretions from the sensory–secretory complexes. The proximal podia are relatively simple in structure and are thought to function more in the transportation of mucus wrapped particles to the mouth rather than in their capture. The difference in structure of the podia and chemical composition of podial secretory cells are taken to reflect the difference in feeding styles of the two species.

Two new species of dorid nudibranchs of the genus Tambja are described from the Indo-Pacific and the temperate waters of the western Atlantic. Tambja haidari sp. nov. is only known from the type locality in Senegal. This species has dark blue ground colour with yellow bands and sky-blue spots, which become real tubercles along the tail. The internal features are typical of species of the genus, with rachidian teeth that lack denticles and with a prostate slightly differentiated from the rest of the vas deferens. Tambja blacki sp. nov., from Papua New Guinea and eastern Australia, has yellow-green or green colour with black blotches. There are two large blotches on the head continuing from the inner side of the base of the rhinophores towards the rear. The notal margin is elevated and joins behind the gill in a well-developed hump. The reproductive system of this species is very characteristic because it has some features more typical of species of Nembrotha than of Tambja (i.e. vaginal gland absent, prostate spread over the bursa copulatrix and wide and elongate vagina). These descriptions bring the number of species of Tambja found around the world to 31.

Burrow wall sediment (BWS) and chamber debris (CD) of Pestarella tyrrhena burrows were isolated and compared to surrounding sediments differentiated into surface sediment (SS), deep ambient sediment (DAS) and embedded ambient organic debris (EAD). The focus was on the meiofauna community along with granulometric characteristics including organic content (OC) and bacterial abundances.

Clear trends were found for all parameters: the shrimp significantly increased OC within its burrow and affected grain size distributions. The oxidized burrow walls were highly consolidated, consisted of poorly sorted sediment enriched with silt and clay, and contained small particles of macrophyte debris, while coarse inorganic and organic particles >500 μm were concentrated in the CD. Bacterial abundances (epifluorescence microscopy direct counts, SYBR Gold staining) were positively correlated with OC and were significantly higher in BWS than in SS or DAS. Nematode numbers were elevated three-fold and foraminiferal densities by two orders of magnitude in BWS versus non-burrow sediments. Among the anoxic sediments (DAS, EAD, CD) meiofauna densities in CD were highest. Nematode community analysis (PCA, CANOCO) revealed considerable differences between BWS and SS. The BWS harboured more taxa and was dominated by deposit feeders, while in SS epistrate feeders prevailed.

These effects on different levels demonstrate the ability of P. tyrrhena to create a specific microenvironment within the burrow. The burrow walls were most influenced by the shrimp's activity, which corresponds to their nutritional role.

The morphology and infraciliature of an endoparasitic ciliate, Boveria labialis, isolated from respiratory trees of the sea cucumber, Apostichopus japonicus, were investigated using living observation and silver impregnation methods. Based on the present and previous studies, an improved diagnosis is supplied: marine Boveria, size in vivo about 30–100×15–30 μm, body slender and flask-shaped, with a protruding lobe measuring 5–15 μm in length; one ovoid macronucleus and one micronucleus; single contractile vacuole positioned in posterior 1¼ of body length; 17–26 somatic kineties; paroral membrane and membranelle 2 forming a double anticlockwise spiral of nearly two turns.

Three species of Distaplia from the Mediterranean are described: D. bermudensis is a species introduced from the western Atlantic Ocean, which principally differs from the native D. magnilarva in having hermaphroditic zooids. The new species D. lucillae differs from the preceding ones in the structure of its stomach wall which is regularly plicated both externally and internally. Distaplia lucillae has colonies with hermaphroditic, but only male ripe, zooids and exclusively female colonies; this is a condition closely related to D. magnilarva though different. A key to European Distaplia is provided.

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

During a study on the parasite assemblages of two endemic catshark species, the dark shyshark (Haploblepharus pictus) and the puffadder shyshark (Haploblepharus edwardsii), from the west and south coasts of South Africa, a trypanosome new to science was observed in the blood of all sharks examined. This trypanosome species, Trypanosoma haploblephari sp. nov., is characterized by its large size, particularly its width, the shape and orientation of the cell nucleus, and its geographical location. Trypanosoma haploblephari is the first species of elasmobranch trypanosome to be described from southern Africa and represents the first description of a blood parasite from South African sharks.

A new species of Ophiomisidium is described and regards about reproduction are presented. It is the first species in the genus to posses, apparently, a brooding development. Very few specimens of species of Ophiomisidium have previously been collected, but over 3000 specimens of the new species were collected on the continental shelf and slope (60–810 m depth) off southern Brazil. They were obtained during the REVIZEE Programme, the first extensive surveys to examine Brazilian ophiuroids from depths greater than 200 m.

A new species of Thyasiridae, ‘Leptaxinus’ indusarium sp. nov. is described from the Indus margin, off Pakistan. The generic affinity is tentative and possible alternatives are discussed. It occurs between 800 m and 1000 m water depth in a low oxygen environment, where it is relatively abundant. The ecological setting is described and data suggest that this species is not chemosymbiotic.

Coney (Cephalopholis fulva) otoliths were collected from 1997 to 1999 off the central coast of Brazil. Analysis of the edges of otoliths sections suggests that one translucent and one opaque zone are formed once a year. Coney age and size-ranges were 2–25 years and 172–428 mm total length (TL) respectively. The von Bertalanffy growth equation was TLt=316(1−e−0.138(t+5.301)). The maximum age observed in this study is well above that previously reported for coney.

The two zoeal and megalopal stages of Porcellana cancrisocialis are described and illustrated from laboratory-reared larvae. At an average temperature of 25°C, Zoea I of P. cancrisocialis lasted seven days before moulting to Zoea II which, in turn, lasted eight days to reach the megalopa. Larval features of P. cancrisocialis are compared with those of other species of Porcellana. Porcellana cancrisocialis exhibits similar but distinguishable features from those observed in Porcellana sigsbeiana and Porcellana platycheles. This species resembles P. sigsbeiana more than P. platycheles in the setation and aesthetasc pattern of Zoea I and II, but the relationships of these three species are not clear.

We report on results of a trawl survey during 2003–2004 to assess the abundance of demersal fish resources in the Persian Gulf and Oman Sea. Samples were taken at a total of 316 trawl stations selected following a stratified random procedure. Catch rates (catch per unit area, CPUA) and total biomass were estimated. Total demersal fish biomass was estimated to be approximately 73,000 tonnes in Persian Gulf waters and approximately 39,000 tonnes in the Oman Sea. The lowest CPUA was recorded in the west of the study area (stratum A, approximately 1700 kg/n.m.2) and the highest in the east (stratum Q, 13943.4 kg/n.m.2), although density of commercially important species was higher in the central area (stratum K). Catch rate and biomass varied significantly in relation to seabed depth. Commercially important demersal species made up around 60% of the estimated total biomass. The most abundant species groups were rays, catfish, grunts, nemipterids and carangids. Several important species (e.g. silver pomfret, croakers and sharks) appear to have declined since the late 1970s while others, such as rays and catfish, have increased.

The mussel Perumytilus purpuratus is distributed from Ecuador to the Strait of Magellan on the Pacific coast; and also extends along the Atlantic coast up to La Lobería, Argentina. The species forms dense three-dimensional matrices which constitute a microhabitat for a wide variety of organisms. Here we test the hypothesis that factors determining habitat structural complexity and environmental heterogeneity of Perumytilus matrices have significant effects on the associated macrofaunal community. In total we found 92 invertebrate taxa in P. purpuratus matrices. The number of layers (stratification) in the matrix had a significant effect on evenness: the greater the stratification, the lower the evenness index. Sediment retention by matrices in sheltered sectors had a significant effect on evenness: greater sediment retention resulted in lower evenness. Sediment retention also determined significant differences in macrofaunal assemblages. In matrices without sediment retention, mussel layering and the presence of algae on the shells of P. purpuratus determined significant macrofaunal differences. As a dominant competitor, P. purpuratus plays a major role in intertidal rocky shores where it is present, structuring communities and determining local biodiversity.

The present work describes the complete larval development of Mithraculus sculptus (two zoeal stages, the megalopa) and the first crab instar from laboratory cultured material. The larval morphology is compared with other descriptions currently available for the Mithrax–Mithraculus complex: Mithraculus coryphe, M. forceps, Mithrax hispidus, M. pleuracanthus, M. spinosissimus and M. verrucosus. Although the different species of the Mithrax–Mithraculus complex display uniform morphological characters, the first zoeal stage of M. sculptus differs from other species in the setal meristics of the carapace and the number of aesthetascs of the antennule. The second zoeal stage differs in the number of aesthetascs of the antennule and the number of setae in the distal margin of the coxal endite of the maxillule. The megalopa of M. sculptus can be distinguished by the presence of 3–4 aesthetascs and a simple seta in the distal segment of the antennule. The morphological differences between the larvae from the genus Mithrax and Mithraculus are insufficient to support the separation of the two genera using adult morphology. Future studies should address in detail setal meristics.

Etmopterus spinax is one of the most abundant predators of the upper continental slope off the Algarve (southern Portugal), where it is captured in large quantities in deep-water fisheries. The feeding habits of E. spinax off the Algarve were investigated through the analysis of stomach contents of 376 individuals. Prey composition was described and maturity, sex and size related variations in the diet analysed. The overall diet of E. spinax suggested a fairly generalized benthopelagic foraging behaviour primarily tuned to pelagic macroplankton/microneckton, teleost fish and cephalopods. Sex and maturity related differences in the diet were not significant. Two main ontogenic diet shifts were observed at about 17 and 28 cm total length. Small and medium sized immature sharks had a diet dominated by eurybathic crustaceans, chiefly Meganyctiphanes norvegica and Pasiphaea sivado. Larger individuals consumed more teleosts and cephalopods, in part associated with scavenging as a new feeding strategy. With increasing shark size the diet diversified both in terms of resources exploited and prey size.

A new hake species, Merluccius tasmanicus sp. nov., is described from New Zealand waters and another species, Merluccius australis is redescribed. Merluccius tasmanicus sp. nov. differs from all other congeneric species in the following combination of characters: upper profile of the head slowly concave; lateral line slowly concave in the caudal region; body depth 4.9–5.9 times in standard length (SL); orbital diameter 6.1–7.1 times in head length, 2.1–2.2 times in snout length and 1.6–1.9 times in interorbital width; second dorsal fin rays, 42–43; anal fin rays, 42–44; lateral line scales ∼164. Merluccius australis is redescribed to clarify the identity of this species. Merluccius australis differs from all other congeneric species in the following combination of characters: upper profile of the head straight; lateral line straight in the caudal region; body depth 6.6–7.1 times in SL; orbital diameter 4.5–5.4 times in head length, 1.2–1.7 times in snout length and 1.0–1.3 times in interorbital width; second dorsal fin rays, 40–43; anal fin rays, 40–43; lateral line scales, more than 155. Merluccius tasmanicus sp. nov. is found in New Zealand and Patagonian waters and occasionally in Japanese waters; Merluccius australis is reported in both New Zealand and Patagonian waters.

Calliopaea bellula, a sacoglossan opisthobranch, was recently found in the Ria Formosa, a coastal lagoon in southern Portugal feeding upon eggs of the cephalaspidean opisthobranch Haminoea orbignyana, the second most abundant gastropod inhabiting the sea grass habitats in the lagoon. The feeding behaviour of C. bellula is described together with photographic images of this process. Egg-masses of other common opisthobranch species collected in the Ria Formosa were also offered, but they were always rejected. This is the first known case of predation on eggs of H. orbignyana.