Mass swarming of a basically sessile terebellid polychaete was observed in the free water column off the south-west coast of Madagascar. Specimens are described and tentatively identified as Loimiamedusa (Savigny, 1818). Swimming behaviour is documented and the phenomenon is discussed as a flight reaction to an environmental disturbance event.

Moult cycle of Liocarcinus arcuatus in the Ría de Arousa (Galicia, north-west Spain) was analysed in relation to: (a) temporal changes; (b) spatial variability associated with both different environmental patterns (type of bottom, depth, etc.); (c) sex; and (d) body size. A total of 4275 females and 4103 males of L. arcuatus were caught in three different areas of the Ría de Arousa, selected as being representative of two types of habitat: a beach zone and two mussel raft culture zones (in the inner ría and in the outer area). Five moult stages were established on the basis of the degree of calcification in the exoskeleton. Only a small portion of the population (less than 15% in practically the whole year) were found monthly in one of the early postmoult stages (Stages A and B). Spatial and temporal variability of the moult cycle of L. arcuatus in the Ría de Arousa was found to be significant (P<0·001). There were no important spatial differences in the moult cycle of L. arcuatus females, by contrast, males showed a greater degree of spatial variability.

The Monaco shrimp Lysmata seticaudata is a warm temperate species with strong potential for the marine aquarium industry and knowledge on embryo production and brood loss during incubation is essential for the establishment of proper maturation techniques. Average (±SD) brood size of small (total length (TL) 40–44 mm), medium (TL 48–52 mm) and large (TL 58–62 mm) simultaneous hermaphroditic (SH) phase were 753 (±215), 1351 (±163) and 1810 (±264) newly extruded embryos, respectively, in early reproductive season (ERS); and 745 (±258), 1314 (±191) and 1813 (±219), respectively, in late reproductive season (LRS). Senescence does not seem to occur in the Monaco shrimp, since during both ERS and LRS larger SH shrimp always presented a higher number of embryos and negative allometry was not recorded. No significant differences in brood size were recorded among broods at different embryonic stages of shrimp in the same size-class in both ERS and LRS. Brood losses recorded from embryonic Stage 1 to Stage 4 for small, medium and large shrimp were 14.3%, 11.3% and 8.9%, respectively, for ERS and 10.9%, 14.4% and 12.2%, respectively, for LRS. The mean embryo volume in the same development stage was not significantly different among the small, medium and large shrimp, and between ERS and LRS for shrimp of same size-class. For all shrimp size-classes during both ERS and LRS, mean embryo volume significantly increased from 108.5% to 127.9%, from first to last embryonic stage. The occurrence of sex change does not affect egg production since small females in ERS (before the major period of sex change) and LRS (after the major period of sex change) had similar brood sizes.

A new species of leptostracan (Crustacea: Phyllocarida: Leptostraca) belonging to the genus Nebalia, N. troncosoi sp. nov., is described from specimens collected off the Galician coast (Iberian Peninsula, north-east Atlantic). The new species is relatively common in sandy bottoms. It is characterized by having a long rostrum, an eye with small distal lobes, an antennular flagellum with up to seven articles, the exopod of the second maxilla longer than the first article of the endopod, and acute denticles along the posterior dorsal border of pleonites 6–7.

Biochemical changes during the reproductive cycle of Aristeus antennatus (Crustacea: Decapoda) on the Portuguese south coast were investigated. Proximate chemical composition, lipid classes, fatty acid profiles, glycogen and cholesterol content were determined in the muscle, ovary and hepatopancreas (HP) during a period of one year (October 2000–September 2001). Gonadosomatic index (GSI) increased significantly in June and July and during the maturation process. Hepatosomatic index (HSI) also increased throughout the ovarian maturation. A positive correlation between lipid levels in the ovary and GSI (r=0.53, P<0.05) and HSI (r=0.30, P<0.05) was found. The muscle showed very low lipid levels and higher percentages of polar lipids. Higher proportions of neutral lipids, mainly triacylglycerols, were observed in both ovary and HP. Both ovarian and HP cholesterol increased with maturation. Protein and glycogen content in the muscle, ovary and HP did not vary as a function of ovary maturity stage. From the different tissues analysed, the glycogen is mainly stored in the HP and to a lesser extent in the muscle. In both ovary and HP the major fatty acids were 16:0, 18:1(n-7), 18:1(n-9), 20:5(n-3) and 22:6(n-3), and significant increase in the levels of monounsaturated fatty acids were observed in ovary during sexual maturation, which indicates these compounds as the major sources of energy during embryonic and early larval development.

The parasitic isopod Syscenusinfelix is recorded from the Mediterranean, based on 19 specimens from a depth range of 375–2071 m. The first ovigerous female of the species is also recorded. Patterns of possible parasitism were suggested based on the depth distribution of S. infelix, and their possible host macrourid fish below 900 m depth in the Catalano-Balearic basin.

A new species of the hermit crab genus Pagurus (Crustacea: Anomura: Paguridae) is described from Brazil. This is the first new species described in 30 years, with morphological characteristics of the exilis group.

Stomach contents of 533 jumbo squid, Dosidicus gigas, ranging between 14·5 and 87·5 cm dorsal mantle length were collected on a monthly basis in the central Gulf of California from November 1995 to April 1997. Fish prey were identified by sagittal otoliths, cephalopods by beaks and crustaceans by exoskeletal features. The diet was dominated by Benthosema panamense, an abundant near-shore nyctoepipelagic myctophid that forms dense aggregations. Another myctophid, Triphoturus mexicanus, several micronektonic squid, pelagic red crab and small pelagic fish such as northern anchovy and Pacific sardine played a secondary role. The largest differences in diet were due to spatial and monthly changes, while differences regarding squid size or sex were smaller. Prey size (averaging 5–7 cm) and prey number did not vary with size of jumbo squid. Jumbo squid in the slopes of the Guaymas basin feed on abundant schooling mesopelagic micronekton of annual nature with a quick response to environmental changes, which could partly explain the large annual fluctuations of this commercial resource.

Spatial distribution patterns of two sessile gastropods belonging to Vermetidae, Vermetus triquetrus and Dendropoma petraeum, were studied in June 2001 in north-eastern Sardinia (Mediterranean Sea, Italy). Density of individuals was assessed within quadrats positioned on a shallow (0·1–1 m depth) rocky substrate of different lithological types (limestone and granite), at a hierarchy of spatial scales. Density of D. petraeum is significantly greater on granite than on limestone, while V. triquetrus does not show any differences related to rock type.

The decapodid and first two juvenile stages of the caridean shrimp Campylonotus vagans from the Subantarctic Beagle Channel (Tierra del Fuego, Argentina) are described and illustrated in detail. The complete larval and early juvenile development of this species from rearings under controlled laboratory conditions were analysed. Zoeal morphology in two stages of an abbreviated development was identical to a description from plankton and hatched larvae of a previous work, and therefore we only compare and discuss slight morphological variations in this study. The first juvenile is large and already resembles some features of adults, lacking all ventral rostral and the fourth dorsal rostral spine only which appears in the following stage, and the second pereiopod not yet being as predominant as in adults. Sexual determination is not yet possible up to the described second juvenile stage. The abbreviated larval development in a Subantarctic shrimp species is discussed as an adaptation to low temperatures and pronounced seasonality.

The capture of a specimen of Kentrocapros rosapinto at Vema Seamount in the south-east Atlantic Ocean is reported as the first record of this species in the Atlantic Ocean. This species was previously known only from the western Indian Ocean.

Specimens of the onychoteuthid squid Moroteuthis ingens were collected from four sites in the Southern Ocean: Macquarie Island, the Falkland Islands, the Chatham Rise (New Zealand) and the Campbell Plateau (New Zealand). Spatial variations in diet among these areas were investigated using stomach contents and lipid and fatty acid profiles. Myctophid fish were prominent prey items at all sites, and the diet at New Zealand sites contained temperate myctophid species that were not identified at other sites. The diet at the Falkland Islands differed considerably from other sites due to the large proportion of cephalopod prey that had been consumed by M. ingens. This is likely to be due to the absence of key myctophids, such as Electrona carlsbergi, and the abundance of smaller squid such as Loligo gahi and juvenile M. ingens over the Patagonian Shelf. Stomach contents data could not be used effectively to determine dietary differences between the Chatham Rise and Campbell Plateau, largely due to differences in sample sizes between these sites. Lipid class and fatty acid profiles of the digestive gland indicated that the diet of M. ingens differed significantly between the Chatham Rise and Campbell Plateau, despite the relative proximity of these sites. We conclude from total lipid content that this was due to a reduction in food availability to M. ingens at the Campbell Plateau. The highly productive waters of the Subtropical Front pass over the Chatham Rise, whereas the Campbell Plateau is situated in less productive sub-Antarctic water. Differences in oceanographic conditions are likely to have driven dietary variations between these two sites.

To examine the biological effects of tributyltin (TBT) exposure, the caprellid amphipod, Caprella danilevskii, was exposed to five levels (0, 10, 100, 1000 and 10 000 ng l−1) of TBT during the embryonic stage (five days). Although the female proportion was 36% of the total in the control, the female proportion changed dramatically in the hatched juvenile, i.e. the proportion of females was found to increase to 55·6% at 10 ng l−1, 85·7% at 100 ng l−1, and 81·8% at 1000 ng l−1. All specimens died in 10 000 ng TBTCl l−1 within five days after spawning due to the acute toxic concentration for the species. Reproductive inhibitions such as brood loss and oogenesis inhibition occurred even at 10–100 ng TBTCl l−1 exposures in the short-term period in both parental females and their offspring females. The embryo survival rate in the offspring decreased drastically as the TBT concentrations increased, with the decrease being observed at TBT concentrations as low as 10 ng l−1 (69%) during the five days. In parental females, the survival rate also decreased at more than 100 ng TBTCl l−1, despite movement after five days into seawater with no TBT added. Data suggest that nanogram concentrations of TBT similar to those encountered in coastal waters around the developed countries can directly affect sex proportion, reproduction, and survival in the caprellid.

A new species of the copepod genus Tortanus (Atortus) (Copepoda: Calanoida), T. (A.) insularis, is described from the coastal region of Rodrigues Island, Mauritius, an isolated island in the south-western Indian Ocean. This new species can be assigned to an Indian faunal element, the recticauda species group, in the Indo-West Pacific recticauda species complex. It exhibits the closest relationship to T. (A.) recticauda recorded from the southern Red Sea and Arabian Gulf, rather than the closer distributed T. (A.) capensis, recorded from off South Africa.

Temporal variations in copper, iron and zinc levels in the periwinkle, Littorina littorea, were investigated to determine whether levels were affected by the sex of the organisms and/or by the presence of two species of trematode parasite. Significant monthly changes in concentrations of all these metals were found, with levels varying according to periwinkle sex and parasite infection. Periwinkles infected by either Cryptocotyle lingua or Renicola roscovita had reduced copper and iron concentrations compared to same-sex uninfected periwinkles, although infected periwinkles generally contained higher concentrations of zinc. Periwinkles infected by the more invasive C. lingua rediae had lower copper concentrations than those infected by R. roscovita sporocysts. These results clearly indicate that in areas of high parasite prevalence L. littorea is not an ideal metal-biomonitor.

Portunus pelagicus (Crustacea: Portunidae) was collected monthly for a minimum of two years from two marine embayments (Cockburn Sound and Koombana Bay) and two estuaries (Peel-Harvey and Leschenault) that are located between 32° and 33°S on the lower west coast of Australia. A birth date of 1 December, derived from estimates of the peak time of spawning, was used to determine the average age of crabs in the main size cohort(s) in carapace width–frequency histograms for each month in each water body. The resultant carapace width-at-age data for each sex in Cockburn Sound and the Peel-Harvey Estuary, in which recruitment occurs at an early age, were then described using a seasonal von Bertalanffy growth curve. The results demonstrated that the growth rates of P. pelagicus differed significantly neither between females and males nor between crabs in the two water bodies and that growth was highly seasonal, with little or no increase in size occurring during the cold winter and early spring months. They also showed that relatively few P. pelagicus live beyond 18 months and indicate that, as a result of legal restrictions against retaining ovigerous crabs and the poor quality of recently-moulted females, fishing mortality is far lower amongst female than male crabs. The fact that the carapace widths attained by P. pelagicus at the end of its first year of life in Cockburn Sound (105 mm) and the Peel-Harvey Estuary (109 mm) were very similar to those in the Leschenault Estuary (105 mm) and Koombana Bay (107 mm) into which that estuary discharges emphasizes that the growth of P. pelagicus in each of these systems was similar. Data are also presented which strongly indicate that the second moult undergone by mature females is accompanied by an increase in the relative size of the abdominal flap.

The phylogenetic relationships within the family Spongicolidae were examined based on a cladistic analysis of 38 adult morphological characters with reference to two outgroup species of the family Stenopodidae. The strict consensus tree identified Microprosthema as the most basal genus, followed by Paraspongicola, Spongicola and the remaining genera. The Spongicoloides represents the most derived genus among spongicolids. The genera Spongicola, Spongicoloides and Spongiocaris should be redefined, because they formed paraphyletic clades. The cladogram indicates that symbiosis with the hexactinellid sponges is coincident with the loss of gills, exopods on maxillipeds 2 and 3, and with the loss of spination on carapace, pereopods, abdomen, tail fan etc. These losses in the spongicolids are thought to be secondarily derived in relation to their sponge-associated habitat.

Feeding, as estimated by egestion rate, in coastal epibenthic mud snails Hydrobia ulvae living continually submerged in lagoon-like conditions varies significantly with time of day. Both in the field and in the laboratory, egestion rate is maximal around mid-day and minimal at twilight. This variation, here ranging in magnitude from mean lows of some nine faecal pellets h−1 to highs of 34 h−1, is consonant with likely rhythms of availability and productivity of their microphytobenthic food.

The influence of estuarine zonation in a coastal lagoon on the population variability of exploited penaeid shrimps Farfantepenaeus aztecus, F. brasiliensis, F. duorarum and F. notialis (Crustacea: Decapoda) at the ‘Ría Celestún’ Biosphere Reserve, Mexico, was evaluated. Monthly samples of shrimp and environmental factors were taken throughout 1997 and 1998 in three zones (seaward, middle, inner) of Celestún lagoon. Salinity and aquatic vegetation biomass exhibited a clear spatial heterogeneity of habitat. A total of 20,757 shrimps were collected mainly at the seaward zone, which registered the highest salinity and aquatic vegetation biomass. This revealed the critical contribution of the seaward zone as the most suitable habitat for shrimp populations, mainly for recruits. Results support the implementation of spatially-explicit management strategies, such as the closure of the seaward zone for fishing activities. The significant relationship between the recruits and the subsequent abundance of shrimp in the lagoon also support this operational measure.

This study presents electron microscopy (SEM, TEM) observations on the putative settlement receptors of the fourth antennulary segments. The TEM data from all nine setae are from the outer dendritic segment. Eight of them have morphological characteristics, indicating bimodal sensory properties while one seta (sE) is presumed to be a unimodal mechanoreceptor. We suggest that setae A and B are stimulated by the water flow, seta D is olfactory, seta E detects the topography of the substratum by touch, and the subterminal setae are touch chemoreceptors. No function is suggested for seta C.