Study of type and other material using scanning electron microscopy has permitted the recognition of three new species and one new genus of Arctic and boreal calloporid anascans. Originally described from the Gulf of St Lawrence, Callopora whiteavesi is reassigned to Flustrellaria, a calloporid genus not previously reported extant. Material from north-east Greenland misidentified as C. whiteavesi is described as C. weslawski sp. nov. The new genus Septentriopora is introduced for calloporids lacking pore chambers, with a distolateral pair of small interzooidal avicularia that face proximally or proximolaterally, and a reduced ovicell. The type species of Septentriopora, Tegella nigrans, has frequently been misidentified. Many of the supposed records of this species belong to two other species, described here as Septentriopora karasi sp. nov. and S. denisenkoae sp. nov. The apparent ovicell in S. karasi is particularly unusual, being vestigial and kenozooid-like in morphology.

Using flow cytometry, two distinct populations of virus-like particles (VLP) and heterotrophic bacteria were defined within the 12 cm water layer immediately overlying healthy, diseased and dead acroporid corals. Bacterial abundances were similar in overlying water for all coral types, however, VLP were 30% higher above diseased corals than healthy or dead corals. Mean virus to bacteria ratios (VBR) were up to 30% higher above diseased corals than above healthy or dead coral or in distant water. Concomitant with increasing VLP concentrations within 5 cm of coral surfaces, VBR distributions were generally highest above healthy and diseased coral and depressed above dead coral. These results suggest fundamental shifts in the VLP and bacterial community in water associated with diseased corals.

Two types of alvinocaridid shrimp postlarvae were taken at plume depth over the Kairei and Edmond hydrothermal vent fields in the south-west Indian Ocean. These postlarvae were superficially indistinguishable from similar postlarvae taken previously over hydrothermal vents in the Atlantic. The micronekton invertebrate taxa in the water column over the Kairei and Edmond sites were similar to those in the Atlantic. The most frequently taken deep-water fish at Kairei was an unidentified cyemid snipe eel, whereas in the Atlantic its place was taken by Gonostoma bathyphilum and species of the melamphaeid Scopeloberyx. Previous sampling over East Pacific Rise hydrothermal sites at 13°N failed to take any alvinocaridid postlarvae, but the ostracod Gigantocypris agassizi was a major component of the micronekton.

The influence of food concentrations (0.5, 1 and 2×105 cells ml−1) and temperatures (20 and 30°C) on the survival, development, organic carbon and nitrogen content of Balanus albicostatus larvae was evaluated. The effect of food concentration on the subsequent ageing and metamorphosis of cypris larva was also determined. At lower food concentration and temperature, naupliar development duration was prolonged and the rate of metamorphosis of nauplius to cyprid was low. The rearing food concentration affected organic carbon and nitrogen content of the nauplii, which was also reflected in non-feeding cyprids. A decrease in the carbon content was observed with cyprid ageing at 5°C. Metamorphosis was higher in 8-d aged cyprids when compared to 2-d aged cyprids, and was positively influenced by the natural biofilm.

The composition and spatial distribution of the mollusc fauna on the subtidal soft bottoms of the Ría de Aldán (Galicia, north-western Spain) were studied by means of quantitative sampling and multivariate analyses. The faunal distribution was mainly conditioned by a sedimentary gradient that was defined by a decreasing grain size from the mouth towards the inner margins of the ría. Several assemblages were determined which could be defined according to the classic terms of ‘community’ and ‘facies’. A ‘Venus fasciata community’ and a ‘facies of Goodallia triangularis–Pisione parapari’ are present in coarser sandy sediments of the outer ría area. The communities characterized by ‘Venus gallina’ and ‘Tellina fabula–Tellina tenuis’ were found in the fine sand bottoms at the centre and margins of the ría. The shallower and muddier sediments in the inner ría showed a mix of typical species from the ‘Abra alba’ and the ‘Venus gallina’ communities, and in the Río Aldán's mouth could be distinguished a facies of a protected zone.

Orchomenella crenata is recorded for the first time from the Irish Sea. Some authors have previously questioned the validity of this taxon due to its morphological similarity with Orchomenella nana and have placed it in the synonymy of O. nana. The question of its validity is resolved by the re-description and comparison of both species.

Lipid and fatty acid composition in Gammarus aequicauda from Mar Piccolo (Ionian Sea, southern Italy) were studied during the spring months. Simultaneously, samples of the macroalgae Chaetomorpha linum were also collected from the same area. During these months Chaetomorpha linum was the main food source of Gammarus aequicauda. The main lipid classes were phospholipids (PL) and triacylglycerols (TG) both in Gammarus aequicauda and in Chaetomorpha linum with similar concentrations. But PL was the main lipid class in Gammarus aequicauda and TG in Chaetomorpha linum. On average unsaturated fatty acids represent the preponderant part in both G. aequicauda and C. linum. Gammarus aequicauda had a higher level in monounsaturated fatty acids (MUFA), on the contrary polyunsaturated fatty acids (PUFA) were the dominant unsaturated fatty acids in C. linum. Both were characterized by high levels of 18:0, 18:1(n-9), 20:5(n-3) and 20:4(n-6), in particular C. linum had a high proportion of 14:0 and the ratio of 18:1n 9/18:1n 7 was high.

Plasmids and phages influence bacterial phenotype and may serve as vectors for transferring genes between bacteria. In the present study, we examined 130 marine bacterioplankton isolates for the presence of plasmids and prophages. Samples were obtained in spring, summer and autumn in the Baltic Sea proper. Plasmids and inducible prophages were found in 19% and 28% of the isolates, respectively. During spring, plasmids and prophages were 41–55% and 30% more common compared to the summer and autumn measurements and prevalence varied up to five-fold between bacterial phylogenetic groups, with the highest plasmid prevalence found in Bacteriodetes (41%), and lysogeny being common in α-, β-, and γ-Proteobacteria (32–50%). Plasmid genome sizes ranged from 1.5–15 kb with most in the 2.1–4.0 kb size-range. No plasmids showed identity to the broad-host-range incompatibility groups N and P. Phage genomes ranged in size from 8–87 kb, with 57% being 35–45 kb in size. Strain typing of phages with similar genome sizes by means of DP-RAPD (degenerated primer randomly amplified polymorphic DNA) showed that all were different (except two that were not resolved). In PFGE (pulsed-field gel electrophoresis) 34% of the lysates produced multiple bands. Transmission electron microscopy suggested that these originated from several phage morphotypes indicating that polylysogeny is common. The widespread distribution of small cryptic plasmids as well as of lysogeny and polylysogeny in Baltic Sea bacterioplankton may have important implications for bacterial phenotype and for lateral gene transfer; hence, the ecological significance of these vectors in marine environments requires further study.

Kingiella chilenica, a brooder mollusc, inhabiting soft bottoms of estuarine tidal flats of southern Chile, is well suited to study larval recruitment. It is a tiny semelparous clam with an annual cycle, and whose recruits must survive an inhospitable winter season prior to growing and reaching reproductive maturity in the following summer season. The population dynamics of this clam was studied through periodic sampling over two successive years to follow fluctuations in its' abundance. Obtained data on embryo production and recruit survival over both periods shows that population abundance varied widely between the two years of study. A high level on recruit survival through the winter of the first year resulted in high numbers of adults in the corresponding summer reproductive season. An inverse situation occurred in the second year, with lower recuit survival and, consequently, fewer reproducing adults. However, the lower abundance of adults in the second year was compensated by their having a higher survival rate over the reproductive season as compared with adults of the previous year. Independently of the abundance of the adults, the number of embryos incubated per female was very similar between both periods. Consequently, we suggest that the net contribution of juveniles produced by females per unit substrate was similar between the annual cycles studied. As predicted for a semelparous species (high reproductive effort), the maximization of the reproductive contribution was clearly reflected by a drop in adult somatic weight, particularly in incubating females. Previous data on abundance for this population suggested inter-annual differences of a high magnitude, with periods (e.g. 1986–1988) with abundances reaching 2–6× that presently reported. Probably, stable environmental conditions (e.g. 1986–1988) promote high abundance and survival of reproducers allowing a large contribution of recruits, which in turn show high degrees of survival through the adult phase. The years reported here (2003–2005), however, represent a period of population decline to lower, perhaps minimum, levels.

Two new species of free-living marine nematodes of the genus Elzalia, Elzalia gerlachi sp. nov. and Elzalia striatitenuis sp. nov. from the Yellow Sea, China, are described and illustrated. Elzalia gerlachi sp. nov. is characterized by relatively large body length (1540–1740 μm in males; 1510–1780 μm in females), spicules 135–160 μm (3.33–3.90 anal body diameter) and complex gubernaculum. Elzalia striatitenuis sp. nov. is characterized by rather small body size (560–660 μm in males; 570–630 μm in females), short cephalic setae 2.5 μm long (21.4–31.3% of head diameter), spicules 65–85 μm (4.06–4.67 anal body diameter) and relatively simple gubernaculum. The two new species can be distinguished from other species of the genus by length and structure of spicules and gubernaculum. Pictorial and tabular keys to the genus are given.

The development of sex-specific characters is described for the deep sea North Atlantic/Arctic shrimp genus Bythocaris. A number of species were examined in the collections of Russian institutions including B. biruli, B. curvirostris, B. irene, B. leucopis and B. payeri. The pattern of size-specific variation in the masculine characters, i.e. the development of the modified appendix interna on the endopodite of the first pleopod and the appendix masculina do not indicate the presence of sex change (protandric hermaphroditism) in the life history.

Aspects of the feeding behaviour of Ergalatax contractus (Muricidae) were studied. Field experiments demonstrated that large numbers of individuals of this species, comprising ∼90% of a suite of gastropod scavengers, were attracted to baited traps in the subtidal sands of Lobster Bay, Cape d'Aguilar Marine Reserve, Hong Kong. Laboratory experiments identified the effective chemo-detection distances of E. contractus as 60 cm in still and >80 cm in flowing water, respectively. The average times to arrival at bait in still and flowing water were 92.3 and 69.0 min, respectively, but were significantly less for individuals experiencing a longer period of starvation. The mean time taken for E. contractus to consume a meal was 70.6 min.

Comparisons were made between Ergalatax contractus and Nassarius nodifer, representative of a suite of sympatric scavenging nassariids in Lobster Bay. The nassariid arrived significantly faster at bait in both still (30.2 min) and flowing water (20.8 min) than E. contractus and fed faster (25.7 min), as is typical of representatives of the Nassariidae. Although the two species partition carrion resources temporally, manipulation experiments provided evidence for inter-specific competition between them. That is, although E. contractus possesses the morphological and behavioural characteristics of a predator, its opportunistic scavenging abilities have led to its success and numerical superiority on the shallow subtidal sands of Lobster Bay. The dominance of E. contractus in Lobster Bay, and elsewhere in Hong Kong, is unusual. Here, the normally predatory E. contractus, far outnumbers all other scavengers, possibly because of an enhanced, largely allochthonous, supply of food which it is able to exploit by virtue of its previously identified opportunistic habit of scavenging the leftovers of other predators. The presence of inter-specific competition between E. contractus and a sympatric suite of nassariids enhances, not impedes, carrion exploitation.

The response of the shore crab Gaetice depressus to predation risk stimuli of either the octopus Octopus vulgaris or crushed conspecifics was examined at two different time phases in the activity rhythm (active and inactive period) by laboratory experiments. When octopus chemical stimuli were introduced to the experimental aquarium, the crab activity decreased in the active period (night) but not in the inactive period (daytime). When the chemical stimuli of crushed G. depressus were introduced, the activity of the crabs increased in the inactive period although the stimuli decreased the activity in the active period. This indicates that G. depressus adjust their anti-predator response according to a combination of the type of predation risk and also the activity rhythm.

The statoliths of 14 species (193 right statoliths from subadult to adult individuals), belonging to five Cephalopoda families (Sepiidae, Loliginidae, Enoploteuthidae, Ommastrephidae and Octopodidae) were analysed using morphometric methods based on landmarks (geometric morphometry). The aim of the current study is to determine the discriminating power of statolith shape analysis in species identification of Mediterranean cephalopods. Discriminant analyses of the partial warps were able to fully identify (100% discrimination) the species of all families, except Octopodidae which showed some misclassification (correctly classified about 68–90%). These results were also shown by relative warp analysis. Octopodidae statoliths were studied for the first time using geometric landmark-based methods. Greatest differences in statolith shape between Octopodidae species, were in the area that unites the statolith dome with the flat wing. Landmark analysis applied to statoliths can be a useful taxonomic tool in the identification of closely related species.

Off central Chile, around 33.5°S, the freshwater discharge of the River Maipo generates a small- to intermediate-size plume, which moves up to the north driven by the daily sea breeze and with localized effects on a costal zone of about 10–15 km. The influence of this river plume motion on abundance patterns of larval barnacles was studied in a ∼12 km long transect, including 2–3 stations inside the river plume, one station on the visible turbidity front, and two stations outside the plume. Shipboard campaigns were conducted in January (summer), August (winter), and October 2003 (spring). On each occasion, conductivity–temperature–depth casts, bottom track acoustic Doppler current profiler current measurements, size-fractioned chlorophyll concentration, and stratified plankton sampling were conducted. A significantly higher abundance of barnacle nauplii was found at the river plume front than at the plume or outside the plume. Abundance was highest in the upper 10 m of the water column, where most nauplius larvae were found. The river plume appeared as a surface layer of less saline water moving north of the river mouth, with a buoyant frontal structure progressing at speeds of 5 to 20 cm s−1. Although no peak in chlorophyll was observed at the buoyant front, the highest concentration of effective prey size for feeding nauplii (chlorophyl-a <5 and 5–20 μm) was generally associated with less saline plume waters. Thus, the accumulation of barnacle larvae at the front may facilitate foraging, potentially increasing larval growth and energy reserves. Our results suggest that the spatial structure and temporal dynamics of river plumes should be considered by benthic ecologists as transport mechanisms that potentially affect larval delivery and settlement of barnacles on rocky shores.

This study examined the relationship between viral infection and the richness, diversity and composition of bacterial assemblages in the water column. Viruses were enriched by ultrafiltration, added to water column incubation experiments at 15 locations in the North Atlantic, North Pacific, Gulf of Mexico and Southern California. In a separate experiment, viruses were removed from bacterioplankton by diafiltration at the San Pedro Ocean Time Series Station. Bacterial assemblage composition was observed using a high throughput and sensitive molecular fingerprinting analysis, automated rRNA intergenic spacer analysis (ARISA). Diazotrophs were used as a model functional group to represent rare organisms hypothesized to benefit from viral activity, and their richness and diversity was determined by terminal restriction fragment length polymorphism of a nitrogenase gene fragment (nifH). The enrichment and removal experiments demonstrated mixed impacts of viral pressure upon bacterial communities, and we observed significant effects of viruses on several microbial parameters in all but two experiments. However, there was no consistent response of viral enrichment on total bacterial and diazotroph assemblages at stations with similar environmental conditions, suggesting that untested variables, small spatial scale factors, or stochastic processes influence the outcome of viral activities. Across all experiments, the relative abundance of the more common operational taxonomic units (OTUs) in fingerprints were not significantly impacted compared to the abundance of rare OTUs. These data indicate that viruses may have significant influence upon community structure of bacterioplankton; however, effects were not consistent between sampling locations nor water masses.

Viruses are hypothesized to cause enhanced diversity in bacterial communities by regulating the outcome of intertaxon competition. However, concomitant documentation of viral and bacterial assemblage composition in oligotrophic waters are rare, particularly in situ over time, and there is almost no information on the temporal variability in virioplankton assemblage composition in oligotrophic water masses. Assemblage composition of viruses (via pulsed-field gel electrophoresis, PFGE) and bacteria (via automated rRNA intergenic spacer analysis, ARISA) was compared during surface lagrangian drifter deployments in the oligotrophic Gulf of Mexico during summer 2001, 2002, and 2003. In vertical profile, viruses and bacteria both had maximum abundances in surface waters, which decreased with depth; however, the richness of their assemblages was not significantly different between depths, suggesting independence of biomass and diversity. Viral assemblages changed rapidly (0.17–0.32 Jaccard index d−1), which was similar to the rate of change in bacterial assemblages reported in surface waters. Patterns of viral and bacterial assemblage composition were significantly related (P<0.001, r=0.58 between node ranks), and both assemblages clustered primarily by year and then by depth. These cultivation-independent observations demonstrate relationships between viral and bacterial assemblages, which are dynamic in patches of open ocean water. Even at the relatively low phylogenetic resolution of the ARISA and PFGE methods, the results support the idea that viruses may influence the species composition of host assemblages.

Zoeal, megalopal and first crab stages of Pagurus nigrofascia are described and illustrated from laboratory reared specimens. Larvae were reared at temperatures 6°C, 12°C, 18°C, and 25°C. Survival rates of larvae were considerably higher at 12°C and 18°C, but were low at 6°C and 25°C. Larvae and postlarvae of P. nigrofascia can be distinguished from seven morphologically similar species based on adult or larval morphological features. Zoeal stages of this species are distinguished by, for example, setal formulae of maxillule, maxilla and maxilliped 1. The megalopal stage can be identified by the telsonal process, the number of articles of the flagellum of antenna and setal formula on the scaphognathite of the maxilla. Morphological features of P. nigrofascia larvae are similar to those of P. ochotensis, P. kennerlyi and P. pectinatus.

The influence of size and density of the blue mussel, Mytilus edulis and the common barnacle, Semibalanus balanoides on the foraging behaviour of the sea urchin Psammechinus miliaris was examined in laboratory studies. Urchins of two size-classes offered six size-categories of barnacles exhibited a constant preference for the smallest category ([les ]7.5 mm plate length). Ingestion rates were independent of the size–frequency distribution of mussels presented to large urchins of 38–46 mm test diameter, which showed a preference for small–medium sizes (>13.4–17.8 mm shell length). Large urchins ingested a maximum of six mussels a day and increased their consumption in a density dependent manner until reaching a plateau once more than ten mussels were offered. In most cases, the rate of successful attacks decreased with mussel size.

Pairwise comparison experiments to determine the ingestion rate of fronds of the algae Laminaria saccharina showed that P. miliaris had no preference for old fronds with or without epifauna, but young fronds of the algae were frequently rejected. These results highlight the omnivorous nature and semi-selective behaviour of this urchin and demonstrate the potential for it to have an important role in structuring algal and epifaunal communities.

Ostrea edulis was extremely rare in the wild in Strangford Lough from the early 1900s until renewed spatfall was observed at a number of sites in the 1990s. A monitoring programme was undertaken to investigate the presence and distribution of planktonic oyster larvae at nine sites around the lough between June and September in 1997 and 1998 as a precursor to studies of spatfall patterns. Larval densities at sites in the northern basin of the lough were significantly higher than those in the southern basin where larvae were lacking or in low numbers. Densities and sizes of oyster larvae showed significant temporal variation suggesting pulsed larval release. Larval densities also showed significant spatial variation with higher densities at sites closer to commercial stocks pointing to these as the main source of oyster larvae. This hypothesis was supported during a larval flux study over a complete tidal cycle which indicated a 90% net tidal movement of O. edulis larvae from the entrance of the bay where commercial stocks were held to the main body of the lough. Thus the maintenance of dense commercial stocks of flat oysters may provide the key to the redevelopment of native oyster beds in Strangford Lough and elsewhere by providing an initial broodstock nucleus from which larvae can be exported.