Numerous studies have shown that only a small percentage of the organic carbon produced by photosynthesis in the upper layers of the oceans reaches the underlying sediments (see review by Angel, 1984). During intense phytoplankton blooms, plant cells could account for most of the organic carbon contributed to sediments in certain shallow inshore areas (Smetacek, 1980). Examination of the sediments from open ocean environments, however, indicates that the main contribution of organic carbon to these is in the form of faecal material released by zooplankton, for example salps (Iseki, 1981) and larger species of copepod (Schrader, 1971; Krause, 1981).

On the night of 4–5 August 1984 an unusual fish was captured in a trammel net set in Elbery Cove, Torquay, South Devon, by Mr W. Blackmore. Its captor realizing it was an unusual species forwarded it to Mr A. D. (Tony) Mattacola for identification. Tony Mattacola recognized it as a member of the genus Seriola, and using the works of Berry & Burch (1979) and Randall (1968) tentatively identified it as Seriola rivoliana Valenciennes, 1833, a species which had never hitherto been recognized in northern European seas. The identification of the specimen was confirmed when the specimen was sent to the author at the British Museum (Natural History); register number 1984.10.22.1.

Colonization of the littoral zone presents many problems to both sessile and relatively sessile invertebrates. These may be especially acute for inhabitants of the upper reaches of this zone, since suitable niches are usually sparsely distributed there, and are often ephemeral in nature. Consequently, both intraand inter-specific competition for space is likely to be particularly intense.

The widely distributed and abundant, beadlet anemone, Actinia equina L., in common with a number of other littoral anthozoans, is apparently capable of both asexual (apomixis or somatic embryogenesis; Polteva, 1963; Gashout & Ormond, 1979; Orr, Thorpe & Carter, 1982) and sexual (Carter & Thorp, 1979) reproduction. The former results in the production of young, which are brooded within the coelenteron and which appear most suited to local dispersal, whilst the latter, if it occurs, is assumed to involve either ovipary or larvipary followed by a planktonic phase. Study of this species therefore affords an opportunity to investigate the dynamics of colonization and dispersal in an heterogeneous environment, in relation to flexibility in reproductive tactics.

Although intraspecific aggression in the anemone, Actinia equina L. has been behaviourally well characterized in laboratory-based studies (Bonnin, 1964; Brace & Pavey, 1978; Brace, Pavey & Quicke, 1979), both its incidence and functional role on the shore have remained obscure. Since A. equina broods young, which are produced asexually (Carter & Thorp, 1979; Gashout & Ormond, 1979; Orr, Thorpe & Carter, 1982) and which appear best suited to local dispersal, we have previously postulated that aggression is likely to be primarily directed towards maintaining ‘territorial’ space for settling syngeneic offspring (Quicke & Brace, 1983; Brace & Quicke, 1985). As such, this postulated role is functionally analogous to that provided by aggression in the clonally reproducing anemone, Anthopleura elegantissima Brandt, in which it serves to maintain the integrity of clonal boundaries (Francis, 1973, 1976), thereby presumably also facilitating the competitive expansion of those boundaries. Work by Ayre (1983) on the Australian anemone, Actinia tenebrosa Farquhar appears to support this contention, for both local settlement and genotypic clustering were detected within aggregations.

Brander & Dickson (1984) observed that fish production in the Irish Sea is low compared with fish production in the North Sea. They identified the lower number of recruiting fish as being the main reason for this difference. They presented circumstantial evidence suggesting that the low recruitment of fish is in turn linked to the shorter and later production cycle in the Irish Sea but the nature of this link is not understood. An example of the way that fish populations are affected by timing of events in the plankton production cycle is provided by the annual fat cycle of herring. Many workers have shown conclusively that the fat content of the herring is intimately connected with feeding and the time of spawning (e.g. Milroy, 1907; Johnstone, 1915; Bruce, 1924; Hansen, 1955).

Krapp-Schickel (1975) described three closely related species of Leucothoe Leach, which together make up a Leucothoe lilljeborgi species complex (L. lilljeborgi Boeck, L. incisa Robertson, L. occulta Krapp-Schickel) in European waters. Of these, the two species L. lilljeborgi and L. incisa have caused considerable problems to taxonomists. As pointed out by Lincoln (1979), ‘There has been a lot of confusion over the identification of lilljeborgi and incisa and it would be advisable to treat earlier records with caution.’ Despite Lincoln's (1979) work, however, the problem persists, several workers (P. G. Moore & J. M. C. Holmes, personal communications) having noted forms apparently intermediate between these two species.

In order to clarify the situation, we have examined material from localities in Ireland and Britain. It is clear that the existence of apparent ‘intermediates’ is due to unfortunate choice of key characters by Lincoln, one of which requires phase contrast microscopy for correct determination. In his key to species of Leucothoe (1979, p. 172) he separates the two species by the anterodistal margin of coxa 4 being either angular (lilljeborgi) or rounded (incisa) and by the inner margin of the gnathopod 1 carpal process being either toothed (incisa) or smooth (lilljeborgi) (although in the description of L. lilljeborgi (p. 176) this process is described as weakly crenulate). Thus specimens with toothed gnathopod 1 carpal process and angular coxa 4 anterodistal margin, appear to be intermediate. It is apparent from our studies, that both L. lilljeborgi and L. incisa have a toothed gnathopod 1 carpal process, but that the structure of the teeth is quite different as revealed by phase contrast microscopy.

The regulation of major ions in aquatic Crustacea has been extensively studied, and it is hardly surprising that ever-present ionic constituents of sea water such as sodium, potassium, chloride, calcium and magnesium have been incorporated into highly efficient regulatory mechanisms. On the other hand, we know little of the mechanisms governing the uptake and regulation of trace elements, despite the fact that metals such as zinc and copper may be important constituents of enzymes and blood pigment.

In a study of the life-cycle of the hexabothriid monogenean Rajonchocotyle emarginata by Wiskin (1970), attempts to obtain newly hatched larvae were unsuccessful, and it was decided to make a new attempt to culture eggs and hatch larvae, at the same time investigating the effects of those factors found in other monogeneans to influence hatching, such as host mucus (see Kearn, 1974), shadows (see Kearn, 1982) and mechanical disturbance (see Bovet, 1967). The success of these renewed attempts to hatch the eggs of R. emarginata provided an opportunity to study the behaviour of the free-swimming oncomiracidium and attempts were made to relate hatching phenomena and larval behaviour to the behaviour of the host.

The feeding habits and host specificities of the Pycnogonida are poorly known. These usually small, cryptically coloured animals are difficult to observe alive and are mostly collected fortuitously in gross samples taken from trawls and dredges. Any association between the pycnogonids and their food is disrupted in the trawl. Further, the possibility that some of the pycnogonids may have been captured in the water column rather than on the bottom cannot be ascertained from trawl and dredge samples. King (1973) lists only twelve records of pycnogonids actually seen browsing on food organisms. Most occur on hydroids and other cnidarians, and all are from benthic habitats. In more recent papers, Stock reports a pycnogonid seen on a brittle star in the Seychelles (1979), feeding preferences of pycnogonids on benthic cnidarians (1978), and an association between a pycnogonid and a starfish from the Philippines (1981).

Recent investigations (Walker & Rees, 1980; Davis & Wilson, 1983b) have shown that the protobranch bivalve Nucula turgida (Leckenby and Marshall) occupies an important niche in the ecology of Dublin Bay, where it is the dominant organism over much of the southern part of the outer bay. This is an area of moderately sorted fine sand (Harris, 1980) with a pelite (silt and clay) fraction of less than 10% and a consequently low percentage of organic matter of around 1% (Davis & Wilson, 1983 b). Trevallion (1965) described the N. turgida habitat as one of firm muddy sand, adding that the animals avoided mud due to their inability to maintain position or feeding and respiratory currents and also avoided gravel due to their inability to burrow in coarse substrates.

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.

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 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.

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.

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 exact form of the taxonomic relationship between the common or blue mussel, Mytilus edulis L., and Mytilus galloprovincialis Lmk, the Mediterranean mussel, has been the subject of considerable scientific interest in recent years (for a review see Gosling, 1984). While the origins of this separation into two species rests with the original descriptions by Linnaeus and Lamarck (e.g. Soot-Ryen, 1955), interest was stimulated in recent times through the discovery by Hepper (1957) of an ‘unusual’ type of mussel at Padstow in Cornwall which, on the basis of morphological criteria, he identified as M. galloprovincialis (see also Lewis & Seed, 1969). This discovery was followed by a series of electrophoretic investigations providing evidence that the so-called ‘Padstow mussel’ exhibits genetic affinities with M. galloprovincialis from the Mediterranean (Ahmad & Beardmore, 1976; Skibinski, Ahmad & Beardmore, 1978; Skibinski, Cross & Ahmad, 1980). In her recent review paper on the systematic status of M. galloprovincialis in western Europe, Gosling (1984) considers information from morphological, cytological, immunological, electrophoretic and hybridization studies and concludes that M. galloprovincialis is a ‘form’ or ecotype of M. edulis.

Estuaries perform a crucial role in the life-cycle of many fish (Cronin & Mansueti, 1971; Day, Blaber & Wallace, 1981; Dando, 1984). They provide a migratory route for anadromous and catadromous species and an environment in which the limited number of true estuarine teleosts spend the whole of their life cycle. The upper reaches are colonized by certain freshwater species while the lower regions are penetrated by some marine fish during high tide. However, many marine teleosts enter and remain within estuaries for a period of time, often in very large numbers and particularly during the early part of life (see e.g. Gunter, 1938, 1961, 1967; Huddart & Arthur, 1971; van den Broek, 1980; Blaber & Blaber, 1980; Potter et al. 1983; Whitfield, 1983). The recognition that estuaries act as important nursery areas for certain teleosts by providing such features as a rich food source and protection from predation (see e.g. Pearcy & Richards, 1962] Jacquaz, Able & Leggett, 1977; Blaber & Blaber, 1980) has led to such species being referred to as estuarine-dependent (see e.g. McHugh, 1976; Beal, 1980; Fortier & Leggett, 1982).

The common goby, Pomatoschistus microps (Krøyer), is a small, euryhaline gobiid fish which ranges along the coasts of continental Europe from the Mediterranean to Trondheim, Norway, and also penetrates into the Baltic Sea (Miller, 1973). This species, which can be very abundant, is generally distributed in estuaries, salt marsh and shore pools (Wheeler, 1969; Miller, 1971) and experiences a higher degree of environmental heterogeneity than most of the other European gobiids (Wallis & Beardmore, 1984a).