The post-larval shell and hinge development of the bivalves Abra alba (Wood), Tellina fabula Gmelin and Donax vittatus (da Costa) from the recently metamorphosed size to a juvenile size of 1·2–1·4 mm shell length has been examined using scanning electron microscopy. Early post-larval development in the stages up to 1·0–1·2 mm size can involve considerable morphogenetic change and requires careful description with photographic developmental series. The form of the pediveliger larva is present in the early post-larval shell and confirms the identity of the larvae of A. alba and T. fabula. The veliger and pediveliger larvae of A. alba are described. The similar larval form of the tellinacean bivalves is modified by differential margin growth early in post-larval development. Comparison of these bivalves with allied species reveals that the post-larvae are distinguishable at even the smallest sizes by the shell and hinge form. The metamorphic size of A. alba ranges from 0·26 to 0·31 mm, of T. fabula from 0·25 to 0·28 mm and of D. vittatus from 0·25 to 0·35 mm. The bivalve post-larvae were collected from the shallow sublittoral of Oxwich Bay, Bristol Channel, U.K., and the larvae from the overlying waters, during the years 1980–2.

The genus Epizoanthus Gray is represented in the north-east Atlantic by three species, all of which live commensally with pagurid crabs. The shallowest-living of the three, Epizoanthus incrustatus (Duben and Koren) occurs with Anapagurus laevis (Bell) within the depth range 20–200 m (Manuel, 1981). Epizoanthus paguriphilus Verrill and Epizoanthus abyssorum Verrill are associated with Parapagurus pilosimanus (Smith), the former within the depth range 600–1550 m and the latter at 3500–4350 m.

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.

Two forms of the genus Mytilus, M. edulis L. and M. galloprovincialis Lmk inhabit the rocky shores of Devon and Cornwall (Hepper, 1957). According to Gosling (1984), controversy has existed since 1860 as to whether M. galloprovincialis is a separate species or a subspecies of M. edulis. In a review of the systematic status of M. galloprovincialis, Gosling (1984) analysed the criteria used to identify and classify this form of Mytilus. Gosling did not reach any firm conclusion on the systematic status of these mytilids, but did suggest that the evidence favoured placing M. galloprovincialis as a variety, ecotype or even subspecies of M. edulis.

The maritime basin of the Ranee occupies one of the largest rias of northern Brittany (France) and since 1967, has been the location of a tidal power station. At a high tide height of 13.5 m above chart datum the basin occupies an area of 22 km2 within which Retière (1979) recognized a maritime part of about 17 km2 in extent, where bottom salinities range from 30 to 35‰, an estuarine part with salinities between 20-30‰,, of about 4 km2 and an inner estuary of limited area (1.5 km2) and reduced salinities (less than 20‰).

The capelin of lodde, Mallotus villosus Müller is a salmonoid teleost of great commercial importance, being caught in large quantities by Norway, Iceland, the U.S.S.R. and Canada. The species has a circumpolar distribution, is limited to high northern latitudes, and has been the subject of two major review articles (Templeman, 1948; Jangaard, 1974).

Most Norwegian capelin spawn sublittorally in the Barents Sea, but a population living in a long fjord near Tromsö in northern Norway (Balsfjord) spawns, like the Newfoundland capelin (Jeffers, 1931, Ph.D. Thesis, University of Toronto), between the tidemarks, their sticky eggs adhering to gravel, stones and weed. The capelin from Balsfjord appear to be separate from the Barents Sea stocks, and are now believed to remain within the fjord throughout their life history (Friis-Sörensen, 1983, unpublished Cand. real, thesis, University of Tromsö).

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.

The lumpsucker or lumpfish, Cyclopterus lumpus L. (Cyclopteridae, Scorpaeniformes), is a cottoid teleost, and, like other fish in its family, exhibits many characteristics of a coastal, bottom-dwelling fish. It is globiform, has no swimbladder, possesses a large abdominal sucker (formed from the pelvic fins), and lays demersal eggs which are brooded by the male parent for many weeks (Fulton, 1907; Cox & Anderson, 1922; Yesipov, 1937; Zhitenev, 1970; Mochek, 1973). The species spends the breeding season in shallow water, where both sexes may be seen attached to the rocks by their suckers. Early researchers (Couch, 1863; Day, 1880–4; Smitt, 1892) believed that the adults retreated to rocky bottoms in deep water after breeding. However, later workers (Cox & Anderson, 1922; Saemundsson, 1926, 1949; Andriyashev, 1954; Bagge, 1964; Blacker, 1983; Daborn & Gregory, 1983) have demonstrated that the lumpsucker spends much of its larval and adult life living epipelagically and in mid water in coastal and oceanic areas upon macrozooplankton (e.g. ctenophores, mysids). The term ‘semi-pelagic’ seems the most appropriate label for its mode of life.

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.

The current nomenclature for cells in the hepatopancreas of decapods is based on the classification of Jacobs (1928) and Hirsch & Jacobs (1928). They described the E-(embryonic), F-(fibrillar), B-(blister-like) and R-(resorptive or absorptive) cells. More recently the M-(midget) cell has been described (Al-Mohanna, Nott & Lane, 1984).

Accounts of the structure of these cells are reviewed by Gibson & Barker (1979) and the B-cells most closely resemble those described and illustrated in this paper for the period 24 h after feeding.

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 small species of Pogonophora that are widely distributed in sediments along the Continental Slope and in the Norwegian fjords (Webb, 1965; Southward & Southward, 1967; Southward, 1971,1979) carry Gram-negative bacteria in the posterior part of the body (Southward, 1982). In this they resemble the giant pogonophores (Vestimentifera) that live around hydrothermal vents in the Pacific ocean floor (Cavanaugh et al. 1981; Cavanaugh, 1983). The bacteria in both groups are autotrophic (Felbeck, 1981; Southward et al. 1981), capable of synthesizing organic matter from carbon dioxide. The bacteria in Riftia and other vent pogonophores appear to obtain energy by oxidation of reduced sulphur compounds (Felbeck, 1981; Felbeck, Childress & Somero, 1981). Hydrothermal vent waters may contain as much as 6 nut dissolved sulphide (Edmond et al. 1982; Edmond & Von Damm, 1983), which is diluted to about 200-300 μM near the giant pogonophores, whose blood can transport sulphide without affecting the affinity of its haemoglobin for oxygen (Arp & Childress, 1983; Powell & Somero, 1983; Childress, Arp & Fisher, 1984).

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish, Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crab Carcinus maenas losses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobster Homarus gammarus (formerly H. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.

Presence of O-group bass, Dicentrarchus labrax (L.), has been recorded for a number of estuaries and tidal backwaters in the south of the United Kingdom, including the tidal Thames (Wheeler, 1979), the outer Thames at Southend (Murie, 1903), the Medway (Van den Broek, 1979), Langstone Harbour (Reay, 1973), the Dart (Dando & Demir, 1985), and the Tamar (Hartley, 1940). The author has found them, additionally, in Chichester Harbour and in the Cuckmere (Sussex), Teign and Tavy estuaries. Correspondents have reported them from the estuaries of the Blackwater (Cox), Crouch (Wiggins), Lynher (Gee) and Fal (Melhuish); also from the Fleet backwater in Dorset (Fear). It may be inferred that all estuaries and tidal backwaters on the south and south-east coasts of the U.K. constitute bass nurseries, in some degree.*

Variability in the distribution and abundance of the plankton of the western English Channel has been investigated in relation to the hydrography of the region by surveys using the Continuous Plankton Recorder (CPR) (Hardy, 1939) and the Undulating Oceanographic Recorder (UOR) (Aiken, 1981a). Previous surveys in the western English Channel have been restricted in area or in time. Harvey et al. (1935), Holligan & Harbour (1977) and Maddock, Boalch & Harbour (1981) have studied the seasonal succession of the plankton at point stations near Plymouth, with analysis of patterns of seasonal succession and phyto-zooplankton relationships; Boalch, Harbour & Butler (1978) measured primary production at three stations across the western English Channel over a period of eleven years (1964–74); Pingree et al. (1976) have shown that the development of populations of phytoplankton are influenced by the establishment and development of the seasonal thermocline and also frontal regions, both of which are determined largely by tidal streaming.

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.