The development of male characters, notably a penis and a vas deferens, on the female (the phenomenon of ‘imposex’) of the dog-whelk, Nucella lapillus, is described. Three stages are recognized: an ‘early’ stage involving the formation of a vas deferens and a small penis, an ‘intermediate’ stage characterized by the enlargement of the female penis to a size approaching that of the male and a ‘late’ stage during which the female opening (vulva) is occluded by overgrowth of vas deferens tissue. This blockage of the pallial oviduct prevents the release of egg capsules and renders the female sterile. The extent and cause of such reproductive failure is evident from the high incidence of females containing aborted capsules in declining populations close to sources of tributyltin (TBT) contamination. These same populations comprise fewer females than expected and it would appear that the accumulation of aborted capsules within the pallial oviduct eventually causes the premature death of the female.

The stomach contents of 221 sperm whales were examined at the Icelandic whaling station between 1977 and 1981. Evidence of at least eight species of fish and 22 species of cephalopod was found, together with an assortment of foreign bodies including rock fragments and fishing nets. Fish remains were found in 87% and cephalopods in 68% of the sperm whale stomachs in this area, but quantification of dietary input is complicated by differential rates of digestion and variation in the retention of indigestible remains in the stomach. Prey species are benthic or pelagic in habit and are caught by the whale in waters from 400 m to at least 1200 m in depth. One fish, the lumpsucker Cyclopterus lumpus, forms a major part of the diet. Ninety-four per cent of cephalopods are oceanic and neutrally buoyant and 84 % of these are ammoniacal. Cranchiids contribute 57% by number and an estimated 25% of the weight, and histioteuthids 26% by number and 38 % of the weight of cephalopods eaten. Three species offish and two of cephalopod have not been previously recorded in sperm whale diets. Comparison with an earlier study shows that the diet is essentially stable over a 14-year period.

Surveys of the plankton at a depth of 10 m in the western English Channel have been carried out at monthly intervals from 1958 onwards using Continuous Plankton Recorders to provide data on annual fluctuations in abundance of the plankton. Interpretation of these results has been attempted by empirical associations with environmental factors (salinity, sea-surface temperature, radiation, atmospheric pressure patterns, wind speed and current strength). Principal component analysis has been used to extract the main patterns of change and correlation analysis for assessing the relationship between the plankton and the environmental factors. There are complex relationships between the plankton and all environmental factors, supporting previous conclusions that the long-term changes are mediated through interaction between the plankton and the climate. Spectral analysis showed long-term trends and shorter cycles of six and three to four years in both the biological and physical elements, indicating that changes in the western Channel are responding to changes in climate over a much wider area

The mysid fauna of the Rockall Trough consists of more than 35 species partitioned between the pelagic water column and the bentho-pelagic environment. The pelagic mysids are dominated by Eucopia grimaldii, E. unguiculata and Boreomysis microps. The benthopelagic mysids, in a transect from 400 to 2900 m depth, are divided into four faunal associations. Pseudomma affine dominates the 400–800 m depth range; the impinging bathypelagic Gnathophausia zoea and the benthopelagic Boreomysis widens dominate the 800–1300 m range;Michthyops parva and Paramblyops rostrata are co-dominants in the 1400–2300 m range; while Amblyopsoides ohlinii dominates the 2170–2965 m range. The benthopelagic mysid fauna is most diverse at depths below 1400 m. It is dominated by species whose geographical distribution is restricted to the North Atlantic, in contrast to the pelagic mysid fauna, which is dominated by cosmopolitan species. Notes on the breeding season, biology and population structure of several species are given.

Based on analysis of videotape records, species of the genus Argyropelecus are capable of swimming diagonally downwards at considerable speeds without altering their body postures. Morphological evidence strongly suggests that they are able to swim diagonally upwards in a similar way. Their distinctive hatchetlike profile presents a streamlined airfoil in both diagonal and horizontal movements, even though the body is not tilted. Modifications of the caudal musculature probably enable all hatchetfishes (including members of the other two genera, Polyipnus and Sternoptyx) to use the tail for propulsion for both diagonal and horizontal movements. The dorsal fin probably aids in diagonally downward movements and the pelvic and anal fins in diagonally upward movements, whilst the pectoral fins serve as stabilizers for these movements, and as an axis of rotation for striking at prey. The seemingly ungainly shape of the hatchetfish is the result of achieving a streamlined, fish-like shape for horizontal and diagonal movements without tilting of the body, presumably in order to maintain an effective camouflage in midwater.

This paper describes the incidence and pathology of a copepod parasite (Sarcotaces sp.) in two species of deep-sea bottom-living fish. The fish Lepidion eques (Moridae) and Coelorynchus occa (Macrouridae) are common on the continental slope to the west of the British Isles at depths from about 400 to 1300 m and 700 and 2000 m respectively.

In both species the parasite was located beneath the skin. In L. eques it was found primarily on the head, whereas in C. occa it was present on the mid to lower flank, often close to the anal vent. Excision of the parasite from the host tissue showed it to consist of a pyriform sac filled with inky black fluid. Detailed histological investigations revealed the parasite wall to be a highly complex structure. Within the gut fluid shown to be of haematogenous origin, numerous copepod nauplii were often observed.

A large-volume pump system (2.8 m3 min-1) for sampling fish larvae under open-sea conditions is described. Comparative efficiency trials by day and night showed that the pump was generally as efficient, or in some cases more efficient, in capturing larvae than vertically hauled 200 μm WP2 nets, though there was some evidence of visual avoidance by particular larval size classes during daylight. The pump system is particularly appropriate for investigating fine-scale vertical aggregations (1–10 m3) of larval fish in relation to the distribution of their food organisms.

INTRODUCTION

Studies of the distribution of larval fish and their food organisms in relation to physical structure in the water column require sampling techniques capable of resolving fine-scale temporal and spatial distributions. As an alternative to conventional nets, large-volume pumps, sampling at rates in excess of 1 m3 min-1; provide such a capability. Major benefits of using large pumps in addition to temporal and spatial resolution are that a wide range of sizes of plankton including larval fish can be sampled simultaneously in relation to physical and chemical properties of the water column; there is reliable control of the volume of sample filtered and problems of clogging of towed nets are avoided; long series of sequential samples can be taken in studies of small-scale distribution; and instrumentation with in situ CTD and fluorometers at the intake enables real-time control of sampling in relation to physical structure.

General engineering considerations for using such pumps have been reviewed in detail by Miller & Judkins (1981), and a particular area of application has been in power-plant entrainment studies in shallow fresh water (Portner & Rhode, 1977; Bowles & Merriner, 1978; Gale & Mohr, 1978; Ney & Schumacher, 1978; Elder et al. 1979; Leithiser, Ehrlich & Thum, 1979; Cada & Loar, 1982).

A survey of the ecology of the octopus Eledone cirrhosa in Scottish waters is compiled from structured interviews with fishermen, records of occurrence in traps (for lobster and crab), and a research vessel survey. This species is widespread and common throughout the inshore waters covered by fishing activity (shoreline- 140 m) on bottom types ranging through rock, stones, sand and mud. It is caught in all months of the year but is especially common inshore in the summer (July-September) and further offshore on trawling grounds in October-December. The octopus is a normal and regular predator of large Crustacea (Hotnarus, Nephrops, Cancer) caught in commercial traps but gut contents yield little identifiable dietary remains.

Serological methods for prey identification have been applied to the gut contents of a field sample of 100 Eledone cirrhosa from the Moray Firth and 7 from the Sound of Jura. Protein extracts from the crop were electrophoresed (Laurell rockets) into antisera raised against potential crustacean prey species, Cancer pagurus, Carcinus maenas, Crangon crangon, Liocarcinus spp. and Nephrops norvegicus. The strengths of the resulting reactions were evaluated on the basis of peak height, staining density and the number of homocentric peaks of immune precipitates. Sixty-two of the 100 Moray Firth animals gave a positive reaction to one or more of the antisera and the most critical assessment of the results ranked the incidence of the prey as Liocarcinus (15) > Nephrops (10) > Cancer (8) > Crangon (2) > Carcinus (0), a total of 35 reactions from 28 animals. Absence of a reaction in the 38 animals from which appreciable sample volumes were also obtained indicates that alternative prey had been consumed. Of the 7 Sound of Jura animals, 4 gave a positive reaction to Nephrops alone. A total of only 24 animals gave any indication of diet by visual recognition of remains. The value and difficulties of the methodology are discussed.

Populations of the spirorbid Pileolaria berkeleyana ( = P. rosepigmentata) are recorded in harbours at Plymouth, Falmouth and Portsmouth and of three similarly abundant serpulids, Filogranula calyculata and Metavermilia multicristata at Abereiddy and Vermiliopsis striaticeps at Falmouth. Ship-borne introductions may well have occurred but the Abereiddy serpulids have more probably come from undiscovered populations nearby, in areas too rocky and deep for easy sampling.

INTRODUCTION

Three apparently exotic species of tubeworms, a spirorbid and two serpulids, have been established for at least five years in aquarium tanks at the Portsmouth Polytechnic Marine Laboratory. The tanks receive a continuous flow of unfiltered sea water, which is pumped from Langstone Harbour via a header tank, with little if any change in temperature. They contain many slate slabs from a flooded quarry (at Abereiddy, in South Wales), which had been opened to the sea in 1932 and is used as a harbour for small boats. The most recent transfer of slates to Portsmouth was in 1972. The slates were brought in because they bore populations of a native spirorbid (Thorp, 1975), but the associated fauna was not closely studied at that time because a general account of Abereiddy quarry and its fauna was being prepared by Hiscock & Hoare (1975).

The exotic serpulids occurred particularly on the undersides of the slates, but had not been noted by Hiscock & Hoare, nor in any other British fauna list. They also occurred on the underside of a disused heater/cooler plate supporting the slates in one of the tanks, which indicated that they had been breeding in that tank.

Prokaryote organisms have been found in the gills of six species of Thyasiridae, collected in the north-east Atlantic region, from depths of 15 to 1250 m. The fine structure of the gill epithelia and the symbiotic Gram-negative bacteria is described. The bacteria occur extracellularly, between a thin cuticle and the apical membrane of the host cell. This differs from the intracellular position of bacterial symbionts in two lucinid species, Lucinoma borealis and Myrtea spinifera, and many other bivalves already known to harbour symbionts in their gills. Four species of Thyasiridae and Diplodonta rotundata, a member of the closely related family Ungulinidae, were found to lack gill symbionts.

The bivalves Thyasiraflexuosa and T. sarsi have enlarged gills which contain numerous prokaryotes. Gills from freshly collected animals contain high concentrations of elemental sulphur. Homogenates of gill tissue show activity for ribulosebisphosphate carboxylase, adenylylsulphate reductase, sulphate adenylyltransferase and sulphate adenylyltransferase (ADP), indicating that the prokaryotes are sulphur-oxidizing autotrophs. Both species can burrow to depths of 8 cm below the sediment surface and use their vermiform feet to construct channels penetrating deeper into the sediment. T.flexuosa and T. sarsi are scarce in sediments with high hydrogen sulphide concentrations and are not found in sediments where the sulphide zone is below their burrowing depth.

Four species of Idotea and Gammarus locusta were associated with drifting seaweed. In all species and throughout the year juveniles predominated. Peak numbers occurred in summer when most seaweed was collected, but /. emarginata and /. baltica were common also in spring and autumn. All species also occurred freely swimming at the surface. No diel vertical migration was detected.

Drifting alga provides only a temporary and unstable habitat for associated species but is important as a medium for habitat expansion and as a refuge from predators for actively dispersing juveniles.

Breeding activity in all species peaked during the summer but continued at a low level for most of the year.

A minor spawning event by laboratory-held specimens of the septibranch bivalve Cardiomyapectinata yielded approximately 40 developing embryos. Their early ontogeny was observed from the early gastrula stage of development until the developing shell had completely enclosed the embryos and had attained 90% of the prodissoconch size observed on juvenile shells. Available evidence indicates that this species undergoes a non-planktotrophic, direct pre-juvenile development. Support for this view includes the enclosure of the developing embryo in a negatively buoyant, adhesive capsule until an advanced stage of development; poorly developed velar ciliation and lack of prodissoconch II formation. Although incomplete, this, the first study on septibranch pre-juvenile development, reveals that C. pectinata embryos form an external calcified shell in a manner homologous to the lamellibranch bivalves, and develop a velum modified for yolk storage, while lacking the epithelial test or pericalymma characteristic of protobranch bivalves. These data indicate that cuspidariid septibranchs are phylogenetically closer to the lamellibranchs than to the protobranch bivalves.

The larval shell morphology of 14 species of neogastropod from the Rockall Trough, N.E. Atlantic has been examined using scanning electron microscopy. Mode of development has been interpreted from protoconch size and morphological features, from the ratio of protoconch diameter to number of larval whorls and by comparisons with confamilial or congeneric shallow-water neogastropods in which development is known. Eight species have non-planktotrophic and 6 have planktotrophic development. Food availability and feeding strategy are important factors in the development of the two different reproductive strategies in the deep sea.