In an experimental study the cyclopoid copepod Corycaeus anglicus Lubbock was found to ingest Artemia nauplii at much higher rates (up to 15 times) in the light than in the dark. Maximal ingestion rates observed in the light represent daily rations of 70% and 66% of the body carbon for males and females respectively. From experimental observations together with studies of the ultrastructure of the photoreceptors it is suggested that Corycaeus can locate prey visually. This is in contrast to the majority of other copepods which use chemoreceptors and mechanoreceptors.

Live specimens of benthic foraminiferal species Rosalina leei were subjected to a combination of temperature (25°C, 30°C and 35°C) and salinity (25‰, 30‰ and 35‰) to assess its differential response to the annual range of seawater temperature and salinity reported at the sampling site. A total of 216 specimens were used for the experiment. Within the range of temperature and salinity, to which R. leei specimens were subjected as part of the present experiment, growth increased with increasing salinity, whereas increase in seawater temperature resulted in retarded growth. Maximum growth was reported in the specimens kept at 25°C temperature and 35‰ salinity while the rest of the specimens maintained in 30‰ and 25‰ saline water, showed comparatively less growth. The specimens kept at 30°C and 35°C temperature and different salinities showed much less growth as compared to the specimens maintained at 25°C temperature. However, none of the R. leei specimens subjected to the present experiment reproduced during the course of the experiment. The absence of reproduction under the present set of temperature and salinity conditions, probably indicates that R. leei reproduces at a very narrow range of temperature and salinity which is different from the temperature and salinity conditions in the present experiment. It is further inferred that under the present set of temperature–salinity conditions, 25°C temperature and 35‰ saline water is most suitable for the growth of R. leei. Results are significant as the responses of benthic foraminifera to different temperatures and salinity are being used for palaeoclimatic reconstruction.

Both the salmon louse Lepeophtheirus salmonis and its close relative Caligus elongatus are ectoparasitic on Salmonidae in salt water in the northern hemisphere. In this study we monitored population dynamics of these parasites on anadromous brown trout, i.e. sea trout, on the Norwegian Skagerrak coast in the winters of 1998–1999 and 1999–2000. The low salinity was expected to reduce sea lice populations as lice do not tolerate sojourns of more than a few weeks, at most, in freshwater. Results confirmed the presence of both parasite species on estuarine sea trout in winter, and showed that the lice populations go through a bottleneck in this period. Prevalences of infection of both parasite species were very different in the two sampling periods, but fell below 10% in March in both winters. Median infection intensity was 1–2 fish−1. Salinity was statistically related to the presence of C. elongatus both winters, and to L. salmonis in 1999–2000. Temperature appeared to be less important for the abundance of lice.

Lepas anatifera L. is generally found on floating objects in tropical and sub-tropical oceanic waters, where sea temperatures exceed 18–200 C.

INTRODUCTION

The shore crab, Carcinus maenas (L.), rapidly clears bacteria from the circulation to the tissues by virtue of the phagocytic and clumping capacity of circulating haemocytes and fixed phagocytic cells (Smith & Ratcliffe, 1978, 1980a, b; White & Ratcliffe, 1982). If re-infection resulting from the re-entry of sequestered micro-organisms into the circulation is to be prevented then the host must eliminate or incapacitate the foreign particles in some way. The migration of laden host cells to the exterior does not appear to be an important means of disposal of segregated non-self material in the Crustacea (Merril, Mongeon & Fisher, 1979; White & Ratcliffe, 1982), so that the ability to resist infection must reside with the cellular killing capacity, perhaps augmented by humoral antibacterial activity. Indeed, our earlier observations on the disappearance of bacteria from C. maenas gills seem to indicate that their loss resulted from the lytic action of host haemocytes (White & Ratcliffe, 1982), as does the elimination of micro-organisms from the hepatopancreas of the crayfish, Parachaeraps bicarinatus (McKay & Jenkin, 1970a).

Recent exploration of the New England and Corner Seamounts revealed four new species of Chrysogorgia, described here using a combination of molecular and morphological data. These four species are characterized by a sinistral spiral, a character that, with one known exception, has only been reported for Pacific species. In addition, two species have a sclerite composition typical of the Pacific (‘squamosae typicae’). This faunal connection between the Atlantic and the Pacific is confirmed by analysis of the mitochondrial msh1 gene. The exceptional preservation of specimens collected with remotely operated vehicles allows us to discuss the effect of growth on some morphological characters.

Molecular biological methods including genomic and proteomic approaches hold a specific promise to provide new insights into the stress physiology of corals. However, to fully exploit the power of these techniques, aquarium setups are required that allow biological assays under tightly controlled laboratory conditions. Here, details are provided about the successful development of a closed coral mesocosm at the National Oceanography Centre, Southampton. The system can be operated without access to natural seawater and allows long-term observations and experimental studies of reef corals. The individual experimental tanks allow the corals to be exposed, for example, to different light and/or temperature conditions without the need to disconnect them from the system.

The feeding ecology of striped dolphin, Stenella coeruleoalba, in the north-western Mediterranean Sea was studied using stable isotope analyses. Carbon and nitrogen stable isotope ratios were measured in skin and muscle tissues of stranded and by-caught dolphins from six geographical areas in the Mediterranean Sea and Atlantic Ocean. Variation in δ15N in relation to dolphin size is attributed to changes in diet. Nursing calves have a higher trophic level than weaned animals and their δ15N values decrease progressively until weaning, estimated to be at a body length of around 155 cm. δ15N values then increased for larger individuals which suggests changes in diet for mature dolphins. Geographical differences in diet were apparent between the Atlantic and the Mediterranean, although no clear differences were apparent between the five Mediterranean areas. Comparisons of the nitrogen isotope ratios of skin and muscle highlighted a higher fractionation in skin compared to the muscle tissue. Values of δ13C also increased with body length although it appears that this is not only driven by trophic level enrichment. δ13C increases before weaning and the difference in trophic level between newly-weaned and mature dolphins was twice as high for carbon as for nitrogen. Ontogenetic changes in carbon isotope composition may therefore be driven by feeding on deep water prey and dolphin movements outside the coastal feeding grounds. Indeed, seasonal variations in δ13C are suspected to be driven by migration within the Mediterranean basin.

The distribution and abundance of benthic megafauna in areas known to be inhabited by dense gorgonian coral assemblages were examined at Northeast Channel, off Nova Scotia, Canada, in August 2001. Using a remotely operated vehicle, 1–5 video transects during each of 1–2 dives at each of four sites (Rips, Middle Canyon, Hell Hole West and Hell Hole East) were conducted. The relationships in the structure of biological assemblages at three spatial scales: within transects (10s of metres); between dive locations (100s of metres); and among sites (10s to 100s of kilometres) were explored. The most abundant epibenthic taxa included the gorgonians Primnoa resedaeformis and Paragorgia arborea, several suspension feeders (Actinauge verrilli, Bolocera tudiae, an unidentified anemone and encrusting sponge, Ophiacantha abyssicola), the deposit feeder Porania pulvillus insignus and the predatory Solaster endeca. The basket star Gorgonocephalus arcticus was present only on colonies of Paragorgia arborea. Despite large variability in abundance and assemblage composition among transects and dive locations, clear patterns were observed among sites. Mean abundance of most cnidarians and echinoderms was greatest at Hell Hole West. No gorgonians were found at Hell Hole East. The encrusting sponge was most abundant at the Rips and least abundant at Hell Hole East. Cluster analysis and multidimensional scaling (MDS) indicated that, when abundance was averaged across transects for each dive, the megafaunal assemblages fall into groups of dives that separated by site. These differences among sites are most likely related to variability in the physical environment. The epibenthic megafaunal assemblages were as diverse in the presence as in the absence of gorgonian corals, at least at the abundances that we observed. However, the apparent low recruitment and abundance, combined with small population size make these assemblages particularly vulnerable to perturbations.

Kingsnorth Power Station, on the River Medway Estuary, Kent, discharges cooling water into a canalcomprising a 4 km creek system. A comprehensive investigation of the sublittoral benthic fauna of the discharge system was undertaken from January 1979 to September 1981. The benthic macrofauna was sampled monthly at five stations along the system and a sixth in the River Medway adjacent to the creek mouth (DC4); salinity, sea-bed temperature, sediment particle size, sediment redox potential, residual chlorine and meiofaunal numbers were measured. The macrofauna is significantly suppressed at sites along the discharge canal, representing a community with half the number of species as at station DC4, comprising dense populations of a few dominant opportunistic species tolerant of thermal stress (e.g.Tubificoides, Cauleriella), and not those characteristic of organic pollution stress communities. The latter are regular summer immigrants in the creek, but persist only in low numbers if at all in the winter (e.g.Polydora ciliata). This suppression is the result of a 10°C temperature front between the heated discharge water and ambient estuarine water, passing over the sea bed with the ebbing and flooding tide four times each day. The residual gradient of mean temperature along the discharge canal causes some changes in the dominance of those species not eliminated by the temperature front. These temperature effects are expected to be localized, mainly in the area of sea-bed impingement of the discharge water; they are predicted to occur at any thermal discharge in tidal waters where the heated effluent contacts the sea bed.

The reproductive cycle of Nassarius (Hinia) reticulatus was investigated in the Ria de Aveiro on the north-west Portuguese coast during 1992 and 1993. A clear seasonal pattern was observed with the beginning of gametogenesis in August followed by ripening of the gonads in January and February and spawning from February to July. The increase of water temperature above 11°C in February 1993 was associated presumably with the release of gametes. Recruitment inside the Ria of juveniles with 6·5 mm mean shell height was detected in February 1993 and these individuals were spawned in the previous year. Males of N. reticulatus exhibited a considerable variation in length of the penis throughout the reproductive cycle. The accuracy of the use of relative penis length (RPL) index for intersite comparisons of imposex is discussed and the magnitude of the error that might be involved when comparisons are made using populations in different phases of the reproductive cycle is evaluated.

In connection with the work of the Plymouth Laboratory it has been the custom of the Marine Biological Association for several years past to extend its operations during the summer months to the various harbours on the coast of Devon and Cornwall, with a view to making a comparative study of the faunas found in the different localities and of correlating, so far as that may be possible, differences in the character of the fauna with differences in the physical conditions prevailing in each. In former years this has been done by making occasional visits, lasting generally for a few days only, in our small steamer, the Busy Bee. It was found, however, that if investigations of this character were to be satisfactorily carried out some arrangement would have to be made for remaining in one locality for longer periods, and working each harbour in turn in more detail. Mr. J. W. Woodall kindly came to our assistance and purchased the hull of an old cruising yacht, which he caused to be fitted as a small floating laboratory and house-boat, and placed at our disposal for use in connection with the researches. This vessel, the Dawn, which can be towed by our own steamer, has been stationed at Salcombe during the present summer and has proved herself to be very well adapted to the work for which she was intended. We have also to thank Mr. Woodall for defraying the expenses of keeping the Dawn at Salcombe.

Despite the ecological relevance of tropical reefs, information on species composition and coverage on sandstone reefs is very scarce. Most studies on reef systems have been conducted for true coral reefs, ecosystems that show calcareous formations with extensive coral cover and diversity. The aim of this study was to analyse the coverage of benthic assemblages in a submerged sandstone reef (22–24 m) in a relatively non-explored region (Tropical South-western Atlantic). In this area, filamentous algae (43.6%) and sponges (19.6%) are the main components of the benthic reef assemblages. Other benthic reef fauna (ascidians, corals and zoanthids) showed lower coverage, although their importance may vary depending on the area. A negative correlation between filamentous algae and slow-growing reef-building organisms (calcareous algae) was observed. High sand coverage (19.6%) over the reef revealed a high rate of silting. A low coral diversity (only two resilient species) was quantified, and most of the coral colonies were small-sized. The results provide a baseline assessment for a poorly known ecosystem with turbid-water benthic communities and higher sea-surface temperatures near the Earth's equator.

A new species of Hymenomonas Stein, Hymenomonas lacuna sp.nov. from San Juan Island, Washington, U.S.A. is described using light and electron microscope techniques. The cells normally occur in non-motile clumps growing on the sides of the culture vessel. Each cell has a body covering composed of a single layer of coccoliths of unusual construction and several layers of circular unmineralized rimless scales. Occasional small elliptical scales are sometimes found.

The general cytology of the cells is discussed with special attention paid to the unusual pyrenoid and the role of the Golgi body in scale and coccolith production.

The relationship of this species to H. roseola Stein is discussed.

Hensen (,1887) drew attention to the possibility of using a pump for quantitative sampling of surface plankton and, since then, a hose-pump method has been widely used for such sampling at desired depths by Juday (1916), Lohmann (1898,1901), and Thorson (1946). A comparative study by Gibbons & Fraser (1937) suggested that such a pump had outstanding advantages over the vertical net, in quantitative work. However, Korringa (1941), working on oyster larvae, suggested that some plankton animals may be able to escape by swimming against the currents which approach the mouth of the suction hose. Brook & Woodward (1956) noticed an apparently rheotactic response shown by plankton organisms in evading water currents.

The quantitative zoogeography of pelagic zooplankton is a subject very much in its infancy. This is due to a number of causes; firstly, the taxonomy of a large number of animal groups has not been finalized and new species are still being regularly discovered. Secondly, many samples, especially from the earlier expeditions, were obtained from broad depth ranges and without accurate depth measurements or the use of opening-closing nets. This latter problem has been overcome by modern sampling devices (e.g. Baker, Clarke & Harris, 1973).

Underlying the thinking of a lot of previous workers has been the hypothesis that the water masses of the various oceans (usually delineated by means of temperature-salinity relationships (Sverdrup, Johnson & Fleming, 1942)) support a distinct fauna. This point of view has been summarized by Johnson & Brinton (1963), Banse (1964) and Beklemishev (1966, 1971). Examples of studies in which the relationship of species distributions to water masses have been studied are Pickford (1946; the cephalopod Vampyroteuthis infernalis), David (1958,1963; chaetognaths), Bieri (1959; Pacific chaetognaths), Brinton (1962; Pacific euphausiids), McGowan (i960; the worm Poebius meseres) and Haffner (1952; the fish genus Chauliodus). In the last case it was suggested that the oxygen content of the water was also an important factor.

The genus Fucus L. is widely distributed through the cool temperate waters of the north Atlantic and north Pacific oceans. The very large number of sub-generic taxa (> 100) previously recognized was reduced by Powell (1963) to only 6 species. In his revision, Powell recognized F. distichus L. emend. Powell as the most variable of these. He classified the intra-specific variation in this species into 4 sub-species: F. distichus distichus, F. distichus anceps (Harv. et Ward ex. Carruthers) Powell, F. distichus evanescens (C.Ag) Powell and F. distichus edentatus (Pyl.) Powell. Because of reports that intermediate forms existed in Iceland (Jonsson, 1903) and the Faeröes (Börgesen, 1902), Powell (1957 a,b) decided to use sub-specific status rather than specific designation for these 4 taxa. However, within North America the 4 sub-species of F. distichus were often assigned specific rank (e.g. Taylor, 1957).

Results of collections with the ring-trawl to obtain evidence on the vertical distribution of plankton animals in daylight at different times of the year and at night are given.

The vertical distribution of Calanus finmarchicus and Cosmelira pilosella is discussed in relation to the distribution of light intensity in the sea.

Results show that light intensity is apparently the external factor of greatest importance in determining the vertical distribution of these plankton animals in this region.

Many more observations at sea correlated with simultaneous records of light intensity at different depths are required, together with laboratory experiments on the effects of various factors on the behaviour of plankton animals kept under different conditions of light intensity.

‘Reefs’ are listed under Annex I of the Habitats Directive as a marine habitat to be protected by the designation of Special Areas of Conservation. Crucially for the implementation of the Directive, the distinction between what is considered as ‘reef’ and what is not is imprecise, particularly in relation to colonies of the tube-building polychaete Sabellaria spinulosa. Guidelines are proposed for the implementation of the Habitats Directive definition to provide a robust and transparent approach for the benefit of both regulators and offshore industry. Specifically, it is suggested that the conservation priority of a S. spinulosa aggregation could be determined using a scoring system based on a series of physical, biological and temporal characteristic reef features, weighted according to the perceived importance of each feature and augmented with a further score indicating the confidence in the feature score. Suggestions are given as to how these characteristics might be measured and scored, along with an example to illustrate the application of the approach.

A marine fungus, Plectospira dubia n.sp., has been found infecting crustacean eggs and small Crustacea in the Plymouth Laboratory. It has the following characteristics: mycelium mostly intra-matrical, coarse, hyphae 50–100µ in diameter. Sporangia irregularly inflated, emptying by efferent hyphae of variable length and frequently of irregular diameter; sometimes proliferous; wall persistent. Zoospores dicystic and dimorphic, but the first swimming stage largely suppressed, the first zoospores mostly encysting within the sporangium after a short period of feeble activity, then swimming in the second stage. The first zoospores pyriform and flagellate (probably biflagellate): in the second motile stage laterally grooved with two laterally inserted flagella. First zoospores about 1oµ long, when encysted 7–8µ in diameter; in the second motile stage 11–12µ long, when encysted 6–7µ. in diameter. Gemmae numerous, spherical, up to 1OOµ. in diameter. Sexual organs so far unknown.