The relationships between the standing stocks of deposit-feeding benthic invertebrates and benthic chlorophyll-a, phaeopigment and total combustible organic matter were investigated at a series of coastal lagoons and in the type of intertidal soft-sediment sites from which the lagoons originated. Across all the sites, in Norfolk, UK, an inverse relationship occurred between (a) the amounts of chlorophyll-a and of other potential food materials and (b) the degree of coverage by water. The biomass of consumers also decreased with increased water coverage, so that the lagoons supported less biomass than the adjacent high-level intertidal sites. Further, the deposit-feeder biomass supported by unit food decreased with extent of water coverage.

There was no evidence of any relationship between deposit-feeder and food biomass within any single site, in spite of the study period being selected to be that in which there was maximum likelihood of competition for microphytobenthic food. Whilst chlorophyll concentrations may set the maximum achievable level of consumer biomass at these sites, including in the deeper lagoons setting very low potential maximum population densities, the seasonal abundance patterns of the deposit feeders appear to be determined by other factor(s).

The abundance and latitudinal and vertical (0-100 m) distribution of planktonic Foraminifera was investigated on the basis of 38 samples collected in November 1994 in the southwestern Atlantic Ocean (34-60°S, along 51-56°W). Mean foraminiferal densities were 1.5 ind. l−1 (range: 0.15.9 ind. l−1), with highest concentrations in subsurface waters (20-50 m). Couplings between the distribution of chlorophyll a and foraminiferal abundances were very loose. Distribution patterns of the 15 species recorded allowed 6 distinct areas to be defined along the transect surveyed. From north to south these are: Subtropical (dominated by Globigerinoides ruber and G. trilobus), Cold intrusion (Globigerinita uvula), Transitional-Subtropical and Transitional (Globigerina bulloides, Globigerina quinqueloba), Subantarctic (G. quinqueloba), and Antarctic (Neogloboquadrina pachyderma, left coiling). Close comparisons with the yields of a similar data set collected in November 1993 show very good agreement. Foraminiferal thermic régimes were also similar in 1993 and in 1994, but for some species significant differences with previous data were detected. While the southwards extensions of the ranges of warm water species are fairly well circumscribed by the Brazil current-influenced waters, several foraminifers widely used as indicators and palaeoindicators of cool waters (in particular Globigerina bulloides, Globigerina quinqueloba and Globigerinita uvula) were recorded in very significant numbers at temperatures as high as 20-24°C. The implication of these findings for hydrological, ecological, and palaeoecological interpretations is discussed.

The identification of magelonids with mucronate chaetae on chaetiger 9 has long been confused. Until 1977 all corresponding European specimens were erroneously referred to Magelona papillicornis; a Brazilian species. Since then, but without any detailed study, the name M. mirabilis (originally given to a species from Scotland) has been widely employed. However, in recent years, it has become clear that two morphologically similar species coexist in European waters. Magelona mirabilis is redescribed and a neotype designated, and M. johnstoni sp. nov. is formally distinguished. Following re-examination of the other five species present in the region, a dichotomous key and a synoptic table of characters is provided for all seven European species.

An earlier study of metals in the polychaete Owenia fusiformis showed that individuals within intertidal populations were remarkably variable in terms of whole-body concentrations of zinc and copper. Four populations have now been studied, two in south Cornwall (Fal Estuary and Par Sands) and one each in east Devon (Torre Abbey Sands) and north Brittany (Grève de St Michel). Investigations of the distributions of zinc and copper within the body have demonstrated that consistently zinc is concentrated in the middle body whilst copper increases to a maximum posteriorly. Zinc is accumulated in the mid-gut cells in the form of numerous spherules, 1–2 μm in diameter: X-ray microanalysis shows these to be largely composed of zinc phosphate but containing also magnesium, calcium and iron, together with sulphur and chlorine. Viewed under the microscope the spherules are greenish due to a pigment identified by high performance liquid chromatography absorption scanning as a pheophorbide-like chlorophyll-degradation product. In contrast, copper is widely distributed throughout the body and much is deposited as small granules, 0.2–0.3 μm in diameter, in laminar groupings in hypodermal and peri-intestinal tissues. The identity of the green pigment responsible for the characteristic body colour of O. fusiformis has not been specifically determined but it appears to have a copper basis since dark-green tissues have a significantly higher copper content than those with a light-green colour. The possible role of chlorophyll degradation products in zinc and copper uptake is discussed.

A new species of terebellid polychaete, Lanice arakani sp. nov., is described from two specimens collected in deep water at seamounts of the west Pacific by the submersible `JAGO', and comparisons are made with the established species of the genus. Special reference is given to the morphology of the worm's sediment tube and in situ observations.

Serpuloidea were collected by diving within 45 m depth, by indirect sampling in deeper waters (50 and 81 m), and among the fouling settled on oceanographic instruments at various depths (10, 50, 80 and 83 m depth). A total of 33 species or subspecific taxa was found: 25 Serpulidae and eight Spirorbidae. All the species collected are already known for the western Mediterranean and have Atlantic–Mediterranean or worldwide distribution. Several of these, however, may be species-complexes hiding species with restricted geographic ranges. No Lessepsian migrants were found. The number of species found at vent sites was significantly higher than that found at non-vent sites, although no vent-obligate species were recognized. Hydrothermal vents might influence serpuloidean richness through four main mechanisms: (i) increasing food sources to these filter-feeders, due to the chemiosynthetic production by vent microbiota; (ii) enhancing the development of biogenic carbonate mounds, which provide habitats for encrusting and cryptic species; (iii) inducing advective mechanisms that concentrate larval stages in the vicinity of vents and thus favouring recruitment; (iv) creating, through the periodic emission of toxic fluids, a regime of `intermediate disturbance' that allows a larger number of species to coexist.

The cumacean Cumopsis goodsir (Crustacea: Peracarida) was sampled monthly in 1991–1992 in the surf zone of Creixell Beach (north-western Mediterranean), to describe its life history and secondary production. In this unstable coastal soft-bottom area, C. goodsir is one of the dominant species of the subtidal community. The annual mean density of this population was 8.5 ind 5 m−2 and the corresponding mean biomass was 0.19 mg 5 m−2. The overall sex-ratio was statistically in favour of females (F:M=2.1). Brooding females were collected regularly during the whole year and their mean fecundity was estimated at 19.3 ind per marsupium. The demographic analysis of samples suggested that C. goodsir is a trivoltine species. The potential longevity of individuals is less than one year and differs between generations. Using the sizefrequency method, its annual production was estimated at 1.44 mg ash free dry weight 5 m−2 year−1 with a corresponding annual ratio of 7.79.

During the austral spring (December 1996), numerical abundance of copepod species (Crustacea: Copepoda) was estimated from 53 sampling stations scattered over the coastal waters off Mejillones Peninsula, northern Chile. Samples were obtained from two depth strata; 0-50 m and 50-200 m depth. Oceanographic data over the three-day cruise indicated that coastal upwelling was actively occurring during the survey.

A total of 19 species was identified, of which four of them, Paracalanus parvus, Oncaea conifera, Oithona similis and Calanus chilensis, accounted for more than 80% of the whole copepod assemblage in terms of numerical abundance. Using the K-means exploratory analysis the 53 locations were grouped into two clusters: an upwelling type and a non-upwelling type. The former characterized by locations nearshore, with low temperature (<17°C) and high chorophyll-a (>13.4 mg m−3), while the latter had warmer waters (>18°C) and low chlorophyll-a (<4.8 mg m−3). Chlorophyll-a (chl-a), distance to shoreline and temperature at 10 m depth (T10) were all significant variables ( P<0.05) for clustering analysis. There was a strong negative correlation between T10 and chl-a ( P<0.01). The same clustering technique, based on species abundance, suggested the presence of a unique cluster, whose composition was dominated by P. parvus, O. similis, Acartia tonsa and Centropages brachiatus. Stepwise multiple regression showed that these species were also strongly correlated to chl-a and T10. Together these analyses suggest that water mass circulation during upwelling is the driving force for structuring spatial patterns of copepod distribution. In addition, a vertical distribution parameter suggested that copepods, independently of time of the day, tended to remain in a large proportion in near surface waters, possibly constrained by a shallow oxygen minimum layer. This implies that advection during active upwelling may cause large fractions of populations being transported offshore, allowing zooplankton export to more oceanic waters. Rapid turnover rates of copepods growing continuously year-round, may act as a mechanism to compensate population losses during persistent coastal upwelling.

This study quantifies the prevalence, abundance, and spatial distribution of epibiotic molluscs on six common neogastropod species in sandy bottoms, Hexaplex nigritus, Chicoreus regius, C. erythrostomus, C. brassica, Vasum caestus and Pleuropoca princeps. A total of 1478 epibiont specimens belonging to 74 mollusc species were examined. The most of epibiotic species were typical of hard-bottoms, but a few species were typical of soft-bottoms. The results indicate H. nigritus is significantly more fouled than the other five species. This can be due to a greater availability of small hollows and a strongly ornamented shell in this species. The spatial distribution of epibionts on the neogastropod shells varied significantly among the different areas into which the shell was subdivided for this study. Fifteen sedentary epibiotic species dominated on all host shells. The costs and benefits of epibiosis are reviewed and the epibiont/host relationship appears to be principally beneficial to epibionts, without a clear benefit for hosts.

The taxonomy of Magellanic and Antarctic cadlinids has been for many years in extreme disorder, and the species were not reliably identifiable. Recent collections in Chile and Argentina, mainly by SCUBA, and re-examination of type material provided data for a comprehensive revision. The present study gives new morphological information on all southern species, both by scanning electron microscope examinations of cuticular structures and detailed microanatomical investigation of the genitalia. The high Antarctic Cadlina affinis does not possess an aberrant androdiaulic genital system but, as all other doridoidean nudibranchs, a triaulic system with a separate vagina and nidamental duct. The vaginal duct is short and leaves the vagina distally, distinguishing this species from other known cadlinids. The genitalia of the holotype of C. kerguelensis from Kerguelen Island have been re-examined. In contrast to previous assumptions, it is not conspecific with cadlinids from South Georgia and the Magellanic region because of clear differences in the genital system. The south-western Atlantic C. magellanica is redescribed and considered to be conspecific with the holotype of C. falklandica from the Falklands. A specimen previously assigned to C. falklandica from South Georgia, however, differs from other southern cadlinids due to genital features and is redescribed as C. georgiensis sp. nov. The Argentinian species C. laevigata and C. berghi, cannot be clearly distinguished from C. sparsa, of which a lectotype has been designated and, therefore, are regarded as junior synonyms. Five Cadlina species from the Southern Ocean are regarded to be valid, and their biogeography is briefly discussed.

The bed-forming brittlestars Ophiothrix fragilis, Ophiocomina nigra and Amphiura chiajei from Oban Bay, Scotland were studied using methods previously employed to study chemoautotrophic symbioses. Ophiothrix fragilis and A. chiajei both contain symbiotic bacteria (SCB) while Ophiocomina nigra is non-symbiotic. Samples were taken of Ophiothrix fragilis at approximately two-week intervals for one year. Symbiotic bacteria numbers were determined by direct counting of homogenates of the arms of 50 individual brittlestars. Water samples were analysed for chlorophyll content. Stable isotope ratios for carbon and nitrogen were determined for each homogenate sample. Regular SCB counts were made on the infaunal brittlestar A. chiajei. Homogenate samples of Ophiothrix fragilis, A. chiajei and the non-symbiotic Ophiocomina nigra were analysed to produce fatty acid profiles for each species. Symbiotic bacteria count varied by up to one order of magnitude in both Ophiothrix fragilis and A. chiajei with no evidence of seasonality in this variation. Symbiotic bacteria number was inversely correlated with δ15N but no relationship was established with δ13C. 16:1ω7 and 18:1.ω7 fatty acids were used as putative bacterial markers. Both symbiotic species had higher percentages of 16:1ω7 than the non-symbiotic Ophiocomina nigra. However, only Ophiothrix fragilis appeared to receive appreciable quantities of 18:1ω7 from its SCB. The SCB are heterotrophic and may contribute to the nitrogen budget of the host. The two symbiotic species studied here derive the bulk of their nutrition from conventional feeding but SCB make significant, additional contributions.

A new holothurian species Chiridota hydrothermica (Apodida: Chiridotidae) is described, restricted to hydrothermal vent habitats. The new species is known from the west Pacific (Manus and North Fiji Basins) and the South East Pacific Rise, between 17 and 21°S. The unusual large, lobe-like tentacles of this holothurian, uncommon in the family Chiridotidae, could be an adaptation to facilitate shifts between suspension- and deposit-feeding in the hydrothermal environment. A brief review of all known records of holothurians and other echinoderms at hydrothermal vents is given.

Lancelets of the genus Branchiostoma (amphioxus) are widespread and locally abundant filter-feeding animals in shallow coastal waters of the south-eastern US (up to 5000 ind/m2) and in temperate and tropical seas worldwide (up to 9000 ind/m2). Lancelets are consumed by bottom-dwelling fish and humans. As part of a larger project to aquaculture lancelets, an experiment was conducted to determine the range of diameters of suspended particles filtered and ingested by the Florida lancelet, Branchiostoma floridae (Chordata: Cephalochordata). After a period of starvation, animals were exposed to a suspension of tracer particles of seven different diameters (range 90–0.062 μm) and the protein, ferritin (0.012 μm) and their faeces were examined subsequently for the presence or absence of tracer. Particles ranging from 90–0.062 μm, but not ferritin, were filtered and ingested. Many of the 90 μm diameter particles, however, were excluded from entering the body by the oral cirri. Under experimental conditions, B. floridae filters and ingests particles in the range of ∼100–0.062 μm (microplankton to colloidal particles). This result suggests that the lancelet diet, like that of appendicularians, includes microbial as well as phytoplankton production.

A study was carried out on the morphology (size and shape) of the saccular otolith (sagitta) by means of image analysis on three species of the genus Merluccius (M. gayi, M. hubbsi and M. merluccius). By digitization of the sagittae, morphometry and outline (Fourier harmonic) as form descriptor measurements were obtained, that were subsequently analysed by means of multivariant methods, allowing the intraspecific variability to be quantified. The differences in the intraspecific sagittal otolith variability confirmed spatial differences of predicted groups. The results were associated with environmental and population aspects. The use of combined morphometric measurements for the whole otolith and its corresponding sulcus acusticus were very appropriate for determining the origin of the analysed otoliths. Using both principal components analysis and discriminant analyses, a clear geographical differentiation was obtained for Merluccius gayi (from Chile and Peru) and M. merluccius (from the Atlantic and Mediterranean). In both species, the discriminant analysis predicted that all the sagittae could be correctly assigned within each of the groups studied. However, it was a little less effective at differentiating between the two groups of M. hubbsi (from the San Matias Gulf on the Patagonian Shelf and Argentinian–Uruguayan Common Fishing Zone). As a result, the morphometric analysis of the sagittae otoliths acted as a clear diagnostic tool to differentiate individuals from different geographical distribution areas.

The concentration of phytoplankton chlorophyll-a (chl-a) and primary production within the euphotic zone (at depths corresponding to 100, 30, 10 and 2% light) were measured in the oceanic region of the Oyashio Water, the north-western Pacific, in spring of 1993, 1994 and 1995. The chl-a concentrations ranged from 0.15 to 6.98 mg m−3 and the range of chl-a standing stock integrated from the surface to the 2% light depth was between 4 and 43 mg m−2. The daily primary production integrated from the surface to the 2 and 0.2% light depths was estimated to be between 94 and 1695 mg C m−2 d−1 and between 114 and 2046 mg C m−2 d−1, respectively. Phytoplankton bloom was noticed when the depths of the euphotic zone and the upper mixed layer were similar. The maximum chl-a concentration and daily primary production in the upper 0.2% light depth were comparable to those reported previously in the spring bloom in the coastal, offshore and oceanic regions of the Oyashio Water, and in the summer bloom of the Western Subarctic Gyre in the North Pacific. The magnitude of daily primary production in the phytoplankton bloom in the western subarctic North Pacific (the Oyashio Water and the Western Subarctic Gyre) was comparable with those in the eastern subarctic North Pacific and the subarctic North Atlantic. The magnitude of chl-a in the phytoplankton bloom in the western subarctic North Pacific was higher than those in the other subarctic regions. Varied contribution of large diatoms to the phytoplankton biomass, caused by different iron and silicate conditions was hypothesized to be a leading factor for variation in magnitude of the phytoplankton biomass.

Nitzschia alba (Bacillariophyceae), a colourless (apochlorotic) pennate diatom, was found on the surface of seaweeds collected from the Clyde Sea area between August and December, 1994. This is the first record of N. alba in UK waters. Nitzschia was found to replicate much more rapidly than heterotrophic protists of similar size. At 20°C, cells divided in just 6.9 h and even at 5°C the generation time was only 38.2 h. The ecological importance of these diatoms has been overlooked by microbial ecologists despite the high productivity of coastal ecosystems and recent work that has shown that Nitzschia can utilize seaweed phycocolloids and invade damaged seaweed tissue.

Multivariate analysis of qualitative and quantitative data from algal communities, collected at three coastal areas of the Aegean Sea in the upper infralittoral zone, has been carried out using the PRIMER software. The aim was to detect groups of species reflecting differences in environmental conditions. A multidimensional scaling of the results demonstrated the presence of three different groups of Cystoseira species, corresponding to different hydrodynamic conditions.

Plant size and aspects of the reproductive potential of monotypic and polytypic populations of Fucus spiralis and Fucus spiralis forma nanus were compared. The two formae were distinct, but the differences between them were less pronounced where they co-occurred, suggesting the possibility of a level of inter-forma gene flow. Fucus spiralis f. nanus plants pay a potential reproductive cost in that they produce smaller eggs than F. spiralis, but the two formae appear to have similar levels of total reproductive output (eggs per unit of receptacle tissue).

The fragmentation process in Hydractinia pruvoti (Motz-Kossovska, 1905) which live on shells inhabited by hermit crabs is activated by the intensity of water movement that induces a rapid and abundant production of propagules by transversal fission. Being produced by all kinds of polyps in the polymorphic colony, fragments are very different from each other both in shape and size. After their liberation, fragments first settle on the bottom, then dedifferentiate and produce a network of hydrorhizae from which new polyps arise.

The life history of the hydrozoan, Hybocodon prolifer, was observed. The polyp from the actinula larva forms the stolon soon after metamorphosis. The stolon is dormant during the warm seawater season. The polyp does not produce the medusa. In early winter the stolon starts to form the polyp, and the polyp produces the medusae. Subsequently the polyp forms the stolon. Experimentally the stolon can be induced to form the polyp at any time during aestivation by treatment with low temperature seawater. Neither the polyp from the actinula nor that from the aestivating stolon forms the next polyp. In this case the hydrozoan is solitary. When the polyp forms the stolon with branches, a polyp is formed from each branch after aestivation. In this case the hydrozoan is colonial. If the stolon piece is divided into several pieces, a polyp is formed from each piece. When the contents of the stolon are extruded, the extruded cells form a cellular mass in several hours, and undergo morphogenesis to form a polyp, as does an intact stolon. The stolon is covered by a thick perisarc, and the endodermal cells contain large quantities of yolk-like granules. A few nematoblasts are found dispersed among the endodermal cells.