Using vertical profile data from the upwelling system off northern Chile, the slopes of dissolved oxygen/nutrient concentration regressions have been analysed, in conjunction with a value of 1·4 for the molar ratio of net community oxygen production to nitrate-driven carbon dioxide assimilation, to investigate the stoichiometric inter-relationships between photosynthetic oxygen production and carbon dioxide and nutrient consumption. There was little interseasonal variation in ΔCO2/ΔDIN (nitrate+nitrite) molar ratios, ranging from 10·3 to 11·6 in the near-shore zone of active upwelling and 6·7 to 9·0 in mid-water, between 25 and 50 m depth offshore. Although the former range exceeded the value expected from Redfield-Richards stoichiometry (6·6) by more than 50%, it was in line with published ratios for phytoplankton blooms in coastal and oceanic waters. Mean ΔDIN/ΔPO4 ratios were similar for the near-shore stations and the mid-water, ranging respectively from 7·0 to 10·7 and 8·4 to 11·5, these subRedfield-Richards values mirroring the ratios of the nutrient concentrations in the water and probably implying ‘luxury’ consumption of phosphate. Seasonal variations in the ΔO2/ΔPO4 ratios for the near-shore zone are shown to be consistent with the view that, in the austral spring and summer when upwelling is strongest in the area, the main source of the water coming to the surface is the Peru-Chile Undercurrent, whereas in the autumn, it could be of subantarctic origin.

Whilst evaluating the use of RoxAnn® for benthic biotope mapping it was noted that over certain visually similar sediments differences were observed in the acoustic signature. To assess this phenomenon a number of physical parameters were determined (mean sediment grain size, sediment sorting, sediment organic carbon content and the percentage of sand, silt and clay present in the substratum) from within a survey area in the North Minch. Investigation of the epifaunal and burrowing megainfaunal communities was also carried out using towed underwater television (TV) techniques. Generalized linear modelling showed that changes in Nephrops norvegicus burrow density could account for 94·7% of the variability in the RoxAnn® E1 signal. The model, however, appeared to be improved when both the percentage of silt present and the sorting of the sediment were also taken into account, with 984% of the variance in El being explained. Although improving the original model, the addition of these extra variables was, however, considered insignificant in terms of the variability accounted for by N. norvegicus density alone. The findings of this study are discussed in relation to possible shellfish management.

The free-living benthic copepods and nematodes in samples of decaying leaves and sediment, from a Rhizophora apiculata-dominated mangrove forest bordering the Sungai Merbok Estuary in north-western peninsular Malaysia, were identified to putative species. Analyses of community structure of these taxa revealed that both are concentrated within the surface layers of the sediment; communities associated with decomposing leaves are distinct from those associated with the sediment surface; and variation between physically similar sites within the forest is relatively small. It is suggested that the meiofaunal communities in tropical soft sediment mangrove estuaries respond primarily to salinity and exposure gradients as in temperate non-vegetated estuaries. Copepod communities of the Merbok mangrove system appear to be much more diverse than those in estuarine and saltmarsh habitats in other climatic regions, and detailed faunal analysis suggests that there is a high degree of species endemism, particularly in genera which are only found on decaying plant material.

Trichosphaerium sieboldi is a marine amoeba with a cosmopolitan distribution. The ability of three strains, from different geographical regions, to digest a range of macroalgae was investigated. Prior to these experiments, methods were developed for the axenic cultivation of T. sieboldi. Algae included Fucus vesiculosus, F. spiralis, Laminaria digitata, L. saccharina, Mastocarpus stellatus, Palmaria palmata, Porhyra sp., and Ulva sp. All were degraded with equivalent ease; typically 50% of the tissue biomass was removed within seven days. The wall of this amoeba was studied to obtain clues on how a protist could be digesting macroalgal tissue. The fibrous nature of the outer cell wall presumably allows the wall to part and remesh during consumption of large particles. It is suggested that during digestion of macroalgae, the wall is parted to enable digestive enzymes to be localized along the surface of the seaweed wall, effectively forming an ‘enzyme pocket’. Trichosphaerium has both polysaccharidases and glycosidases, notably glucosidase, cellobiosidase, mannosidase and fucosidase. These enzymes work in concert to facilitate the breakdown of the complex polysaccharides found across the range of seaweeds used. These studies suggest that T. sieboldi could be a primary invader of seaweeds in the field. They also suggest that some protistan groups may be important in the degradation and recycling of algal material in coastal waters.

The first data substantiating the occurrence of diarrhetic shellfish poisoning (DSP) in the central region of the Adriatic Sea (Kaštela Bay) in the summer of 1995 is presented. Toxicity was investigated using bio-assay and HPLC-FD analysis. Analysis of samples displaying toxicity, in addition to small concentrations of okadaic acid (OA), suggested the presence of an unknown derivatized compound at high concentration. A long term survey of the phytoplankton community has been conducted. The origin of mussel toxicity was traced to Dinophysis sacculus, a suspected toxic species.

Seasonal dynamics of bacterial and heterotrophic nanoflagellate (HNF) species assemblages were analysed in Kaštela Bay (middle Adriatic Sea). Dominant patterns identified were: (1) during summer and autumn bacterial abundance was mainly controlled by HNF grazing (top-down), whereas HNF abundance was controlled by bacterial abundance (bottom-up); (2) during winter and spring the coupling between bacteria and HNF was very weak, and bacterial abundance was mainly controlled by resources supply (bottom-up), whereas HNF abundance was controlled by micro-zooplankton grazing (top-down); (3) throughout the year, both bacterial and HNF species assemblages alternated with two periods of stable abundance, first with high and second with low values; (4) top-down effect was dominant in bacterial switching from stable abundance with high values to stable abundance with low values, whereas bottom-up model dominated in inverse process; and vice versa for HNF.

Eight marine oligotrichous ciliates including one new genus, two new combinations, and five new species collected from the Yellow Sea, north-eastern China, are morphologically and biometrically investigated based on observations of living specimens and permanent preparations after protargol impregnation: Strombidium tintinnodes; Novistrombidium testaceum gen. nov., comb. nov. (formerly Strombidium testaceum); Tontonia turbinata sp. nov.; Pelagostrobilidium simile sp. nov.; Rimostrombidium orientale sp. nov.; Strombidinopsis elongata sp. nov.; Strombidinopsis elegans sp. nov., and Strombidinopsis minima comb. nov. (formerly Strobilidium minimum). Four junior synonyms are considered: Strombidium oculatum; S. obliquum; S. hadai and Strombidinopsis cheshiri. A comparison with other known members within Strombidiidae resulted in the establishment of a new genus, Novistrombidium gen. nov. It is similar to Strombidium but characterized by the conspicuously opened girdle kinety with a large gap on its ventral side, through which the ventral kinety extends.

A new species of poecilosclerid sponge from methane seeps on the Louisiana Slope, Gulf of Mexico, USA is described. This thickly encrusting sponge grows around vestimentiferan tubes and has a very patchy distribution. The skeletal structure and the spicule set match those characterizing the genus Ectyomyxilla. The new species, Ectyomyxilla methanophila sp. nov., is distinguished from the remaining species in the genus by the structure of its ectosomal skeleton, where small acanthostyles are never present, and by its choanosomal skeleton, which is barely reticulate and has echinated main tracts. The small size of the choanocyte chambers suggests occurrence of nutritional benefits derived from association with chemoautotrophic symbiotic bacteria. However, the presence of oscules, ostioles, aquiferous canals and choanocyte chambers indicates that this sponge also relies partly on filtration for its nutrition. This is the first record of the genus Ectyomyxilla in the northern hemisphere, and the first non-carnivorous demosponge known to exploit methane-rich marine environments.

All the currently known species of Guitarra with spiny isochelae have been reviewed by SEM: Guitarra fimbriata, Guitarra indica, Guitarra bipocillifea, Guitarra abbotti and Guitarra laplani. A new species from Namibia;Guitarra flamenca, is described, which is characterized by bipocilla-like spiny isochelae similar to those of Tetrapocillon atlanticus, placochelae in two different morphological categories and very robust megascleres. After a revision through SEM of the specimen of Guitarra fimbriata var. indica, it clearly belongs to Guitarra flamenca sp. nov. The morphological variability of the placochelae and the spiny isochelae across the Guitarra-species has been analysed and the main parameters useful to differentiate species are highlighted.

In the common intertidal sea anemone Actinia equina (Cnidaria: Actiniaria) the morphological plasticity and lack of hard parts has caused considerable debate as to what constitutes a species. Over the last several years genetic studies have indicated that this ‘species’ consists of various separate gene-pools which appear to function as cryptic biological species. Conventional taxonomy has often concentrated on the use of a cnidome, the type, structure and number of nematocysts ('stinging’ cells). However, the usefulness of nematocysts to distinguish among various morphs of A. equina and other anthozoan species has recently been questioned. Here we describe the first detailed study of nematocyst differences between two well characterized genetically differentiated morphs with different coloured pedal discs. Measurements were taken from each type of nematocyst in five different tissues. Contrary to expectations, clear and significant nematocyst differences were found between Actinia with red or pink pedal discs and others with green to grey pedal discs. These findings support previous electrophoretic studies and suggest that quantitative descriptions of the cnidome may accurately identify separate species within other genera of Anthozoa.

A new deep-water Actiniaria species, Isanthus homolophilus sp. nov. is described from the French Polynesia. Morphological and ecological differences between the new species and the other known species of the genus Isanthus are discussed. The distinct morphological characteristics that distinguish I. homolophilus, are the presence of a tentaculated columnar margin, the tentacle number (84–96), and its cnida biometry. A further ecological characteristic is the distinct symbiotic relationship that the anemone exhibits towards the decapod Hypsophiys inflata.

During the biological researches of the ‘Service Mixte de Contrôle Biologique’ (SMCB) in French Polynesia (1986–1990) at depths ranging from 100 to 1120 m, a symbiotic association between a deep-water homolid crab, Hypsophrys inflata Guinot & Richer de Forges, 1981 and a sea anemone of the genus Isanthus (Actiniaria: Isanthidae) was collected. Even though this association was described by Guinot et al. (1995) and Chintiroglou et al. (1996), no concise description of the anemone is given. Thus, the goal of the present study was to provide a detailed description of the new anemone species and compare it with other species of the Isanthidae Carlgren, 1938 family.

The methodology followed in our investigation was that of Doumenc & Foubert (1984) and Doumenc et al. (1985). Nematocyst nomenclature used was as proposed by England (1991). Abbreviations: MNHN (Museum National d'Histoire Naturelle Paris).

Results are presented of a comparative study on seasonal variations in population density, population structure and reproductive bionomics of two species of offshore benthic oedicerotid amphipod, Westwoodilla caecula (from 35 m depth) and Monoculodes packardi (from 190 m) in Loch Fyne (Scotland). Observations on live coloration and behaviour of these species in laboratory aquaria are also included. Male W. caecula were, on average, smaller than females. In M. packardi (atypically among Oedicerotidae) the reverse was true. Population densities of both species, calculated from sledge net tows (1-mm mesh), fluctuated erratically over one year (1992). Ovigerous W, caecula were recorded virtually year-round, but were commonest from midsummer to early autumn. Ovigerous M. packardi were noted in spring and early autumn. Monoculodes packardi had a semi-annual life cycle, but the pattern for W. caecula was less clear. The two generations of M. packardi grew at broadly similar rates, presumably associated with the damped seasonal fluctuations in physical environmental factors at 190 m. Female W. caecula possibly moult eight or nine times, and may produce three successive broods in a lifetime (M. packardi may only produce two). A positive correlation was found between fecundity (stage I eggs) and body length in W. caecula but, although a similar trend was apparent in the data for M. packardi, relevant data were too few for significance to be achieved. Ovoid eggs increased in volume by ×2 from stage I-IV in W. caecula, or ×1·5 from stage I–III in M. packardi. Brood sizes were much smaller in W. caecula than in M. packardi, although apparent brood mortality was higher in the latter. There was no significant relationship between the proportion of ovigerous females in the populations of either species and seasonal variation in physical environmental factors considered (temperature, salinity, daylength).

The distribution of Lepeophtheirus salmonis larvae in Killary Harbour was investigated by taking plankton tows from a number of stations on a regular basis during the spring/summer period in 1995 and 1996. Current patterns, ovigerous lice loads on the resident fish and water temperature and salinity were also recorded during the study. Larvae were only found consistently at a station close to a salmon farm at the mouth of the harbour. In the inner harbour, close to the mouths of two rivers, larvae were recovered in sporadic time blocks. Highest densities of larvae were found at the beginning of the study in both years in the inner harbour with a subsequent decrease in the following months. The distribution, density and origin of the larvae are discussed in relation to the prevailing current patterns in the harbour, the ovigerous lice loads on the resident fish and the requirements of the larvae to locate a new host and complete the life cycle.

During the Joint Chilean–German–Italian Magellan ‘Victor Hensen’ Campaign in 1994 an epibenthic sledge (EBS) was used to catch the epibenthic and benthic-boundary-layer macrofauna.

Eighteen EBS samples were taken at 12 locations on a transect through the Beagle Channel. The aims of the study were to describe the epibenthic molluscan species, to quantify their abundances and to describe their distribution. In total 35,087 specimens were collected, yielding 107,223 ind 1000 nr−2. Bivalvia were most abundant 78,615 individuals (52 spp.) followed by Gastropoda (17,289, 52spp.), Aplacophora (4745, 9 spp.), Polyplacophora (4665) and Scaphopoda (1909,5 spp.). The molluscan abundance of the hauls were strikingly different, between 3 and 37,927 ind 1000 m−2 haul. Only stations off the eastern entrance showed high abundances, which was represented at all depths and sediments. Elsewhere the abundances were low. Species richness was highest in shallow water (< 100 m) with 69 species and decreased with depth. But at the deepest station 37 species were found.

Lagoonal mud snails have been shown to suffer approximately 50% mortality between hatching and adulthood. Experiments were conducted in the laboratory to assess the role of predators on the survival of juvenile Hydrobia neglecta (Mollusca: Gastropoda). Adult snails were collected from a lagoon in the Reedland Marshes system at Dunwich, Suffolk, and their eggs hatched in the laboratory, providing a population of juvenile snails which could be presented as a food source. The vessels, kept at environmental regimes close to that of the natural environment, were seeded with juvenile snails at field density. Predator preference was established by exposing the juvenile snails to combinations of potential predators found in the lagoon. One experiment also gave predators a choice of various juvenile snail sizes and other prey species. Juvenile snails remaining alive after the four week exposure to predators were removed, counted and measured. In the absence of other prey, the opisthobranch snail Retusa obtusa preferentially consumed 50% of the available juvenile H. neglecta over a four week period and the nemertean Lineus ruber up to 90%, making them the major contributors to juvenile H. neglecta mortality. The infaunal anemone Nematostella vectensis, did not have a significant impact on snail survival in the experiments but was observed (incidentally) in a separate non-experimental situation engulfing juvenile H. neglecta. The stickleback Gasterosteus aculeatus and the lagoonal prawn Palaemonetes varians, did not contribute directly to the observed mortality of juvenile mud snails, but were found to consume other predators, producing a system of prey preferences in the food chain. Understanding the role of predation contributes to the understanding of ecological processes occurring in rare lagoonal systems.

Three specimens of the giant squid Architeuthis were by-caught in demersal trawls to the west of Ireland, between April and June 1995. All three specimens were mature males, of mantle length 975–1084 mm. Although some intraspecific variation in fin, beak and gill were noticed, all three specimens were tentatively assigned to the species A. dux. The three specimens had food remains in their stomachs and food items identified included Micromesistius poutassou, Trachurus trachurus, Nephrops norvegicus and Eledone cirrhosa. Age estimates were made by counting putative daily growth increments in ground statoliths, and ranged from 294–122 d, giving percentage daily growth rates of 2·96–4·25% indicating a short life cycle and extremely rapid growth.

Octopuses (Eledone cirrhosa (Octopoda: Cephalopoda)) held in an aquarium were subjected to varying conditions of feeding and starvation to evaluate putative indices of feeding and growth. Specific growth rate (%d−1) was linearly related to feeding rate (% of the body mass d−1) in animals with a mean body mass of 250 g at 15°C. Maximum growth rates varied between > 2% d−1 (body weights < 300 g) to < 1% d−1 (body weights ≤ 900 g) but specific growth rates were not related to body weight. Growth rates became negative (weight loss) after one week without food.

The digestive gland index (DGI) was significantly correlated with short and long-term feeding and specific growth rates, and with body weight. Muscle RNA concentration was linearly correlated with growth rate during the previous 1–3 weeks but not with feeding rate. RNA:protein ratios were not different between mid-arm and mantle sample sites but arm tip values were significantly higher. RNA:protein ratio was related to body weight only in feeding animals. It is concluded that DGI is an index of feeding rate and that RNA:protein ratio can be used as an index of recent (~ 4 weeks) growth rate.

A new South African species of the genus Chaperiopsis is described from material deposited in the Muséum National d'Histoire Naturelle, Paris. Chaperiopsis stephensoni is redescribed and figured from the original material.

The genus Chaperiopsis Uttley, 1949 is widely distributed in the southern hemisphere. Numerous species of this genus have been described in different works; notable amongst these are the works of Busk (1854, 1884), Kluge (1914), Uttley (1949), Gordon (1984), Hayward & Thorpe (1988), Reverter Gil & Fernández Pulpeiro (1995) and Hayward (1995). Some previous records of Chaperiopsis spp. from South Africa are included in the works of Jullien (1881), Busk (1884), O'Donoghue & De Watteville (1935), O'Donoghue (1957) and Hayward & Cook (1983).

Growth in ophiuroids is highly variable, and with increasing size and age of an ophiuroid specimen more and more of the innermost growth rings on the vertebral ossicles become overgrown and hence invisible. Two approaches to estimate individual age of slow growing brittle stars using the high Antarctic species Ophionotus victoriae are compared. One method interprets natural growth ring readings as size-increment data, whereas the second method compensates for growth ring overgrowth by means of an iterative corrective approach. Preconditions as well as advantages and disadvantages of both methods are discussed.

This study sheds light on the evolution of aquatic and terrestrial feeding modes in vertebrates, using two aquatic turtles as models. The estuarine aquatic diamondback turtle Malademys terrapin has a feeding mechanism that is similar to the basic feeding mechanism of terrestrial tetrapods (jaw gape cycles incorporate slow opening, fast opening, fast closing and slow closing phases). Strikes upon prey also involve neck extension and cycles of the forelimbs. Malademys terrapin modulate their feeding behaviour and jaw action in relation to the nature of the prey item. Mussels are approached by walking on the substratum, and limb cycles are of small amplitude during the strike. Crabs, whether encountered in mid-water or on the substratum, are approached by swimming, and the strikes partly produced by vigorous upstrokes of the forelimbs, that occur simultaneously with neck extension. Crabs are dangerous prey, and the turtles often strike with the gape already at maximum, minimizing the time needed to bite a limb or other part of the crab. The tongue is not involved in food capture, but has a major role in food manipulation and transport prior to swallowing. Although transport cycles are similar to ingestion cycles, ingestion and transport are easily separable in the species. Malademys terrapin exhibit great distension of the throat during the strike, but this does not appear to generate adequate suction to aid capture of hard-shelled prey; it is suggested that throat distension reduces pressures in front of the advancing snout, thus preventing pressure waves displacing or alerting prey. The pelagic marine turtle Dermodielys coriacea, which specializes in gelatinous prey, relies heavily on suction for ingestion, which overlaps considerably with transport.