Vertical and horizontal hauls were taken at approximately fortnightly intervals from April 1969 to April 1970 at L 3 (lat. 40° 17.7′ N, long. 4° 11.2′ W) and L 4 (lat. 50° 15′ N, long. 4° 12.5 W). Thirty-two species of prosobranch veliger were present at L 35 these larvae were not as numerous at L 4 and only 26 species were recorded. The number of species was highest in the summer: the number of veligers was highest in February. After mid October both the number of species and the abundance of veligers decreased rapidly and remained low until early February. Veligers of some species occurred later at L 3 and L 4 than in more inshore waters and these were probably individuals carried beyond tidal influences which would normally lead to settlement on the shore. They included Lacuna vincta, Littorina littorea and L. neritoides.

Veligers of all ages were found at all depths. At their time of greatest abundance veligers of many species occurred maximally at 5 or 10 m, with a variable decrease towards greater depths and a sudden one towards the surface. This distribution later changed giving a proportionally greater number at greater depth. When numbers were low the larvae scattered through the water column with little or no indication of a preferred depth. An examination of the age composition of veligers of rissoids, Natica alderi, Nassarius reticulatus and Philbertia linearis from certain catches showed that the surface accumulation at the time of abundance was composed of a high percentage of young veligers: in an ageing population there was a higher percentage of larvae, especially the older ones, at greater depths, except for Nassarius reticulatus which consistently showed maximal numbers above 10 m until the larvae became scarce.

The study area for this work includes all the southern edge of the Bay of Biscay, from the north-west Iberian Peninsula to the southern half of the French shelf. The principal aim of this article is to provide a complete overview of the physical oceanography of the area, mainly in its mesoscale aspects, of which there are few published studies, and the implications for early fish life history stages. The results showed the existence of two space and temporal scales for most of the physical processes that occur in the Bay of Biscay, a macroscale for seasonal time periods and a meso and submesoscale for the periods between seasons. The importance of local phenomena, such as upwelling or the variability of the Poleward Current, was observed. The interaction of both scales on these physical processes is discussed and the need for sampling at the submesoscale level to determine the distribution of ichthyoplankton is considered. Moreover, the mesoscale physical oceanography study is essential to improve the knowledge of interactions between strategies and environmental conditions that result in a significant mortality reduction in fish early stages.

The echinoderm skeleton is interesting because its material is so different from that of other invertebrates. It is full of interconnecting cavities, and each piece of skeleton seems to be made of a single crystal of rather impure calcite (Nichols & Currey, 1968). An obvious question for a biologist is whether echinoderm skeleton is in some way better mechanically than other, more conventional, skeletal materials.

Larvae of vent shrimp from the Mid-Atlantic Ridge are known to disperse widely from the adult habitat. Experimental analysis of the temperature/pressure tolerance of the first zoeal stage of Mirocaris fortunata from the Lucky Strike vent field suggest that the upper limit of vertical distribution is determined by temperature. Conversely, the lower limit is controlled by the maximum pressure tolerance of the larvae.

Generation of ion electrochemical potential differences by primary active transport can involve energy inputs from light, from exergonic redox reactions and from exergonic ATP hydrolysis. These electrochemical potential differences are important for homoeostasis, for signalling, and for energizing nutrient influx. The three main ions involved are H+, Na+ (efflux) and Cl− (influx). In prokaryotes, fluxes of all three of these ions are energized by ion-pumping rhodopsins, with one archaeal rhodopsin pumping H+into the cells; among eukaryotes there is also an H+ influx rhodopsin in Acetabularia and (probably) H+ efflux in diatoms. Bacteriochlorophyll-based photoreactions export H+ from the cytosol in some anoxygenic photosynthetic bacteria, but chlorophyll-based photoreactions in marine cyanobacteria do not lead to export of H+. Exergonic redox reactions export H+ and Na+ in photosynthetic bacteria, and possibly H+ in eukaryotic algae. P-type H+- and/or Na+-ATPases occur in almost all of the photosynthetic marine organisms examined. P-type H+-efflux ATPases occur in charophycean marine algae and flowering plants whereas P-type Na+-ATPases predominate in other marine green algae and non-green algae, possibly with H+-ATPases in some cases. An F-type Cl−-ATPase is known to occur in Acetabularia. Some assignments, on the basis of genomic evidence, of P-type ATPases to H+ or Na+ as the pumped ion are inconclusive.

The influence of temperature on larval survival and development was studied in the edible crab, Cancer pagurus, from a population off the island of Helgoland, North Sea. In rearing experiments conducted at six different temperatures (6°, 10°, 14°, 15°, 18° and 24°C), zoeal development was only completed at 14° and 15°C. Instar duration of the Zoea I was negatively correlated with temperature. A model relating larval body mass to temperature and developmental time suggests that successful larval development is possible within a narrow temperature range (14° ± 3°C) only. This temperature optimum coincides with the highest citrate synthase activity found at 14°C. A comparison for intraspecific variability among freshly hatched zoeae from different females (CW 13–17 cm, N = 8) revealed that both body mass and elemental composition varied significantly. Initial larval dry weight ranged from 12.1 to 17.9 μg/individual, the carbon content from 4.6 to 5.8 μg/individual, nitrogen from 1.1 to 1.3 μg/individual, and the C:N ratio from 4.1 to 4.4. A narrow larval temperature tolerance range of C. pagurus as well as the indication of intraspecific variability in female energy allocation into eggs may indicate a potential vulnerability of this species to climate change. Large-scale studies on the ecological and physiological resilience potential of this commercially fished predator are needed.

Within the Chromophyta (sensu Christensen, 1962) a number of genera having benthic phases in which the vegetative cells are embedded in masses of thick, sometimes stratified mucilage, have been described from both marine and freshwater habitats. Examples include Gloeochrysis Pasch. (Pascher, 1925), Geochrysis Pasch. (Pascher, 1931), Sarcinochrysis Geitl. (Geitler, 1930), Chrysotila Anand (Anand, 1937) and Ruttnera Geitl. (Geitler, 1942). In many cases the vegetative stages are so similar morphologically as to be almost indistinguishable, especially in the juvenile condition in which the cells are often arranged in regular blocks (the ‘Sarcinochrysis’ condition) and under such circumstances it is difficult to ascertain their true systematic relationships.

The antifouling performance of the dogfish Scyliorhinus canicula (L.) (Elasmobranchii: Squaliformes) eggcase-embryo combination was studied under experimental conditions, in conjunction with an analysis of fouling on wild cases. The cases were shown to develop an external heterogeneous microbial biofilm, and an internal heterogeneous microbial biofilm (when the case opens) composed primarily of cocci and bacilli. Macrofouling was limited on egg-cases (unless kept under high light intensities). Macrofouling ranged from <5% (recently laid cases) to 42% (>300 days exposure). This is a better performance than many commercial antifouling treatments. There was no evidence that the embryo was involved in the antifouling process. A priori, three hypotheses are suggested that might explain the antifouling mechanism of the dogfish eggcase-embryo combination: (1) the yolk/albumin/embryo emit antifouling chemicals; (2) a bacterial culture develops that prevents further fouling; (3) the case with/without an embryo has antifouling properties. The results presented here support the third hypothesis.

We describe the phytoplankton community and biomass during a summer coccolithophorid bloom sampled over the Patagonian shelf (48.5°S–50.5°S). Those phytoplankton species can contribute to the flux of calcium carbonate out of surface waters. Results from both microscope and high-performance liquid chromatography (HPLC) analysis are shown to complement information on the phytoplankton community. From CHEMTAX analysis of HPLC data, the most important organisms and groups identified were the coccolithophorid Emiliania huxleyi, the haptophyte Phaeocystis antarctica, dinoflagellates, diatoms, cryptophytes, prasinophytes and cyanobacteria. Phytoplankton microscope counts were converted into phytoplankton group-specific biovolume estimates. Although some microscope-identified taxa could not be determined by CHEMTAX, e.g. the autotrophic ciliate Myrionecta rubra, cluster analyses from both techniques showed similar results for the main groups. Both Emiliania huxleyi cell concentration and biomass, and the pigment 19′-hexanoyloxyfucoxanthin were the most important biological features during the sampling period. At surface, nitrate was moderately high (0.2–4.2 µM) in coccolithophorid-dominated samples, whereas phosphate (<0.33 µM) and silicate (<1.35 µM) concentrations were low. Among the environmental factors low Si:N ratios were mainly associated with the dominance of E. huxleyi. Competition and probably differential grazing could also promote a coccolithophorid outgrowth over other photoautotrophs during the summer season in the Patagonian shelf.

Biebl (1939a, b) has found that algae from various ecological groups show marked differences in their resistance to changes in the temperature of the surrounding sea water. He regards this temperature effect as an important factor influencing the distribution of different intertidal algae and points out that a change of only 2° C may prove critical with certain species. One of us (A.D.B.) has studied the resistance of sporelings of various common inter-tidal red algae to changes in environmental temperature and has obtained results similar to those of Biebl.

The 'anchor-dredge' is a lightly built one-sided instrument designed to catch deep-burrowing animals. The depth to which it digs is dependent on the pull of the warp and not on the weight of the dredge.

From a trawler, it is best to work the dredge from the forward gallows, and give it a 'tug' as the ship is moving astern.

Comparative tests and direct underwater observations have shown that the anchor-dredge samples the in-fauna more efficiently than do either large rectangular and oval dredges, or the conical dredge.

A description and plan is given of a larger model, designed for use from a 6o-ft. or 90-ft. ship.

The present study examines the feeding habits of Alepocephalus rostratus, the only species of the family Alepocephalidae in the Mediterranean Sea and the second most important fish species, in terms of biomass, inhabiting the deep slope of the Catalan Sea. Samples were obtained at depths between 1000–2250 m. Diet was analysed for two different size-classes (immature and mature specimens) at three different bathymetric strata during two different seasons. The feeding habits of A. rostratus included a narrow range of mobile macroplanktonic organisms (e.g. Pyrosoma atlanticum and Chelophyes appendiculata) and some material of benthic origin. Pyrosoma atlanticum was the preferred prey item in spring at 1000–1425 m, being very scarce in summer at the same depth as a consequence of its scarcity in the environment during this season. There were some ontogenic differences in the diet of A. rostratus at 1425–2250 m. Adults ingested more and larger prey than juvenile specimens. The scarcity of resources below 1200–1400 m fostered a more diversified diet, as well as passive predation of sedimented material.

In continuation of the scheme commenced last year for making a detailed survey of the marine fauna in the estuaries on the Devon and Cornish coasts, an examination has been undertaken during the present summer (1901) of the Exe estuary. For this purpose the floating laboratory bot Dawn, which has been generously placed at our disposal and maintained by Mr. J. W. Woodall, was towed to Exmouth and moored in the dock there, where she remained from July to September.

Six methods for estimating the numbers of nanoplankton organisms in sea water have been compared. Of these, centrifugation of a living sample, followed by counts of the numbers of organisms in the concentrate, appears to be the most satisfactory method from all points of view. The method is rapid, simple to operate, and gives a result which is strictly comparable with results from counts made under dark-ground illumination of unconcentrated samples, and from counts after concentrating with niters. By this method the organisms counted can usually be assigned to the class and order to which they belong, even if their systematic position cannot be determined more definitely.

The use of species-pure cultures is a necessary adjunct to the direct examination of sea-water samples when studying the distribution, abundance, and annual fluctuations of nanoplankton, as so little is known of the systematics of these organisms.

INTRODUCTION

The deep-sea eel, Synaphobranchus kaupi, is widely distributed on the continental slopes of the North Atlantic (Saldanha & Bauchot, 1986; Haedrich & Merrett, 1988). It was a dominant fish species in epibenthic sledge and semi-balloon otter trawl (OTSB) hauls on the West African slope (Merrett & Marshall, 1981; Merrett & Domanski, 1985). Also in the eastern North Atlantic, it was the most abundant species on the slopes of the Porcupine Sea Bight off south-west Ireland (Merrett et al., 1991; Priede et al., 1994). In the western North Atlantic, it was the dominant species on the middle and lower slopes of the Middle Atlantic States of the USA and on the upper slopes of the Grand Banks off Newfoundland (Sedberry & Musick, 1978; Houston & Haedrich, 1986).

In this study, we analyse spatial patterns of macrobenthic communities of the Río de la Plata system, and assess the species turnover or beta diversity and its relationship with environmental gradients. Macrobenthic samples and physico-chemical parameters were collected from 20 sampling sites along a transect of 560 km, including the freshwater (FW), estuarine (ES) and marine (MA) sectors. Three main assemblages corresponding to the above mentioned sectors were defined with multivariate analysis (cluster, MDS). In total 134 taxa were recorded, 81 in MA, 33 in FW and 38 in ES, represented mainly by polychaete, mollusc and crustacean species. Depth, salinity and %clay showed the strongest correlation with the observed faunal patterns (ρw=0.62; BIO-ENV analysis). Beta diversity varied between dominant taxonomic groups and was positively correlated with changes in salinity. The high variability in the composition of assemblages was reflected in beta diversity, reaching its highest values at the boundaries between the defined sectors. This study suggests that beta diversity represents a useful tool to define ecological boundaries for benthic communities in the Río de la Plata.

Estimations of the brooding and larval developmental periods of the callianassid ghost shrimp, Callianassa japonicu Ortmann (Decapoda: Thalassinidea), under field conditions, were made on an intertidal sandflat in western Kyushu, Japan, during the breeding seasons (June-October) of 1992–1994. Females bearing eyed embryos were able to deposit a further batch of eggs 1–5 d after releasing larvae, and it is concluded that such egg deposition was preceded immediately by mating. Based on rearing experiments carried out in the field, the brooding period was found to occupy between 13 and 22 d during June to October, at pore water temperatures of 20.5-27.5°C and salinities of 33.0–34–5‰, a shorter period than those reported for seven other callianassid species. Based on temporal changes in the densities of larvae released by females and newly-settled juveniles on the sandflat, time-lags between the release and settlement events suggested the period of planktonic development with six zoeal stages and the 1st post-larval stage to range from 20 to 25 d during mid-June to mid-August, at water temperatures of 18.5-24.5°C and salinities of 32.0–35.0‰. This is the second shortest larval period among those reported for seven other callianassid species that have five or six zoeal stages.

Although the practice of recreational feeding of fish by tourists is widespread within marine protected areas (MPAs), the ecological consequences of this activity have received little attention. This research aimed to investigate the influence of artificial feeding on reef fish communities of two Brazilian MPAs. Visual censuses were performed in areas not visited by tourists, in order to characterize the natural community structure of each reef system. In the Maracajaú reefs, the effect of artificial feeding was assessed below a moored floating dock found in the area. Stationary visual censuses were carried out before, during and after the fish feeding activity. In the Maragogi reefs, areas with presence and absence of tourism visitation were established. Transect methodology was employed in each of these areas. On both MPAs, fish feeding was a formal activity and occurred on a daily basis during the course of this study. Within the MPAs, 88 species belonging to 40 families were recorded. In Maracajaú, fish, shrimps and squids were provided by the tourists on the floating dock, which favoured mobile invertebrate feeders, whereas in Maragogi, animal ration and human food were used, causing aggregations of omnivores. Differences were observed in terms of abundance between before and after feeding in Maracajaú and between the control and impacted areas of Maragogi. The data are consistent with fish feeding leading to attraction of determined species, causing an increase in their abundance, also indicating that both the type of food and the extension of activity area are important factors determining the effects on fish communities.

A new species, Diopatra marocensis, is described from the fine sand Abra alba community, Sidi Boulbra, south Moroccan Atlantic coast. The new species is a member of the D. cuprea complex and is characterized by having crescentic nuchal grooves, short ceratophores, a short branchiate region, four pairs of modified parapodia with bidentate pseudocompound hooks, pectinate setae with 11–20 teeth, limbate setae with conspicuously serrated shelf, and subacicular hooks from setiger 13–15. Eggs of Diopatra marocensis sp. nov. are deposited in the parental tube, where they undergo direct development and remain until the young consist of 32–34 setigers.

A clear preference for the actinian anemones Actinia equina, Anemonia sulcata and Anthopleura elegantissima was demonstrated, while the acontian anemones and Corynactis viridis ranked low in the order of preference. The significance of acontia as defensive structures in anemones is discussed briefly. No differences in food preference were found between eolids collected from Plymouth and Millport; and British Aeolidia behaved in the same way towards Californian anemones as did Californian Aeolidia.

The eolids varied in their tendency to bite different species of anemone, but the performance of each individual eolid was similar in different experiments. It is possible that the individual variations may account for conflicting reports in the literature.