The naked dinoflagellate Gymnodinium cf. nagasakiense is responsible for red tides frequently associated with mortality of marine organisms in North European waters during summer (see reviews by Tangen, 1977 and Partensky & Sournia, 1986). This species is currently referred to as Gyrodinium aureolum Hulburt in the literature, since its first occurrence in Norwegian waters in 1966 (Braarud & Heimdal, 1970). However, it was recently found to be morphologically closer to the Japanese bloom-forming species Gymnodinium nagasakiense Takayama & Adachi than to the original Gyrodinium aureolum (Partensky et al., 1988).

Previous work on barnacle biometry has mainly been concerned with the opercular valves, whose shape is often an important taxonomic character (Barnes & Healy, 1969; Henry & McLaughlin, 1975). The well-known change in shape whereby columnar individuals are produced as a result of crowding has also been described by many workers (e.g. Trusheim, 1932; Barnes & Powell, 1950; Subklew, 1969; Crisp & Bourget, 1985). The influence of environmental variables on the shape of the barnacle shell as a whole has been little studied.

Giesbrecht (1895) was the first to report that the luminescence produced by marine copepods was produced by certain ‘skin glands’. In Pleuromamma abdominalis he described specific sub-cuticular cells which were responsible for the production and secretion of luminous material; such cells always contained a greenish-yellow secretion whilst non-photogenic cells were colourless. The only published histological study of luminous cells in copepods is that by Clarke et al. (1962). These authors reported numerous paired cells in the head of Metridia longa, each pair opening through a common pore, the distribution of which was correlated with areas of fluorescence. Clarke et al. (1962) further showed that the cells in each pair had different staining characteristics, and suggested that each of the two cell types produced a different component of the luminescent system, proposed as ‘luciferin’ and ‘luciferase’ respectively. They hypothe-sized that when stimulated, each cell secreted its contents, generating light as the materials combined in the surrounding seawater. Although there has been much work carried out on the physical characteristics and kinetics of copepod luminescence (e.g. David & Conover, 1961; Clarke et al., 1962; Barnes & Case, 1972; Bityukov & Evstigneev, 1982; Herring, 1983, 1988; Evstigneev, 1983, 1984, 1986; Latz et al., 1988) there is still little known of the comparative distribution of luminous cells in a range of copepod species, and even less is known of their detailed structure.

The common goby Pomatoschistus microps (Krøyer), is a small and abundant brackish water fish, which becomes sexually mature after the first winter of life and usually survives for only a single breeding season (Miller, 1975). During a protracted breeding season from approximately mid-April to August or September, the goby can produce up to 9 or 10 separate batches of eggs. It is therefore considered to be an iteroparous species, but because of the short adult life-span during which spawning occurs, this species has been termed an abbreviate iteropare (Miller, 1984). The nest-building activities of the male fish, courtship behaviour and subsequent brood-care are well documented (Vestergaard, 1976).

The importance of feeding pattern is well documented in fish (Jenkins & Green, 1977; Simenstad & Cailliet, 1986) but there are not many reported studies in cephalopods. Feeding patterns, as defined by Jenkins & Green (1977) have been studied, to our knowledge, only in Todarodes pacificus (Okiyama, 1965), Loligo pealei (Vovk, 1972), Loligo opalescens (Karpov & Cailliet, 1978), Illex illecebrosus (Amaratunga et ah, 1979; Amaratunga, 1980) and Nototodarus gouldi (O'Sullivan & Cullen, 1983). Boyle (1983) dealt with aspects of feeding in several cephalopod species but not specifically with feeding pattern. Aspects of feeding in Sepia officinalis have been reviewed by Nixon (1987). The present work describes the daily feeding pattern in Sepia officinalis from data collected in the field.

The Tilopteridales are an order of three filamentous benthic Phaeophyceae found in North Atlantic and Arctic waters (Hooper et al., 1988). Detailed life history studies are reported for Haplospora globosa Kjellm. and Tilopteris mertensii (Turner, in Smith) Kutz. (Kuhlenkamp & Müller, 1985).

The organic content of the shells of molluscs can represent a significant fraction of the total organic content (Bernard, 1974) but it is often neglected in calculations of energy budgets in these animals. This may be in part due to uncertainty about the true values, since published estimates of the organic content of shells show quite wide variation. The species examined and also the provenance of the selected samples contribute to this variation as does also the method of measurement. The methods principally used have been by ignition at various temperatures from 400 to 550°C for various durations between 2 and 36 h (see Shumway & Newell, 1984; Jørgensen, 1976; Mohlenberg & Kiorboe, 1981; Vahl, 1981; Shafee, 1979; Price et al, 1976) or by acid extraction using different extraction proceedures (see Ivell, 1979; Dame, 1972; Horn, 1986; Griffiths & King, 1979). To calculate the energy content of the organic component some investigators have used the Hughes (1970) coefficient of 5.037 cal mg-1, while others have used Paine's (1971) protein coefficient of 2.39 J g-1. Wilbur & Saleuddin (1983) have called attention to the need for more study of these analyses. We present here the results of a study of the shell organic content of three species of molluscs, using two methods for the measurement and giving data on biochemical composition and energy value.

The comparative research programme on harpacticoid copepod assemblages of the west coast of Ireland and northern Finistere began in 1982. During 1981 in Galway, D. Jackson sampled three sandy beaches around Galway Bay (Figure 1), Grattan Road Strand, Silver Strand and An Poll Brean (on Mweenish Island) near Carna (simply called Carna in the following text) and was preparing his PhD thesis (Jackson, 1985). Between 1978 and 1984 in Brittany, P. Bodin had been conducting a long-term ecological survey (Bodin, 1988) of three sandy beaches polluted by the 'Amoco Cadiz' oil spill; Brouennou, Corn ar Gazel and Kersaint (Figure 2). As these six beaches shared common characteristics of granulometry, salinity, temperature and hydrodynamics, it was decided to undertake a comparative study of the systematics, ecology and biology of their harpacticoid copepod assemblages.

Energy values of many cold-water marine invertebrates are available (see Wacasey & Atkinson, 1987 and Brey et al, 1988), but energy values of temperate-water marine invertebrates have not been systematically investigated. In an attempt to determine the energy content of the macrobenthic communities from the bay of Morlaix (western English Channel), the caloric values in a large number of species living in these communities has been measured. This paper is presented as a contribution to the knowledge of the energy content of macrobenthic invertebrates from a temperate sea.

Doliolids are pelagic tunicates which swim by very rapid contractions of the muscle bands that encircle their barrel-shaped bodies; the resulting jet pulses drive them forwards at instantaneous velocities up to 50 body lengths s-1 (Bone & Trueman, 1984). The obliquely-striated muscle fibres within the bands have the unique feature that they lack any kind of sarcoplasmic reticulum or sub-sarcolemmal vesicle system (Bone & Ryan, 1974). Most stages of the rather complex life-cycle of doliolids (Braconnot, 1971a) are small animals, less than 4 mm long; but in one of the species examined the largest may be up to 40 mm. This paper shows that external Ca2+ is required for contraction of the locomotor muscle fibres and that the decremental muscle potentials preceding contractions are carried by Ca2+. In younger stages, the muscle fibres within a band are electrically coupled to some extent, but in older animals, the degree of coupling decreases

The eggs of the polyopisthocotylean monogenean Plectanocotyle gurnardi (van Beneden & Hesse, 1863) Llewellyn, 1941, from the gills of gurnards (Triglidae) develop and hatch readily when maintained in the laboratory. However, the impression was gained that some or all of this hatching might be the consequence of inadvertent shadowing or accidental mechanical disturbance of the eggs by the investigators. Since similar stimuli are known to induce hatching in some other monogeneans (see Kearn, 1982; Whittington & Kearn, 1988) and since such stimuli are likely to be generated by the activities of potential hosts, it was decided to embark on a more detailed investigation of hatching in P. gurnardi and to attempt to learn more about the behaviour of gurnards. During these investigations, the availability of freshly hatched larvae of P. gurnardi presented an opportunity to study their behaviour and to expand our knowledge of their anatomy.

To understand the working of the marine pelagic ecosystem one needs to study the logical frame of the complex food web. This study is much easier in an enclosed water column than in the open sea where biological interactions are often concealed by physical events.

Predation is now considered the main cause of mortality in larval and juvenile fish (Hunter, 1984) and is therefore the most important factor controlling recruitment to the adult population. Marine fish larvae are prey for many different types of predator including medusae, crustaceans and larger fish. When predatory attacks are sensed both adult and larval fish may respond by making a 'C-start', a very fast, simultaneous contraction of the trunk musculature that deforms the body into a C-shape within 20 ms (Eaton & Hackett, 1984). This startle response is mediated by the Mauthner cells, a pair of prominent neurones in the hind brain or by other reticulo-spinal cells located in the same region. As a result of reciprocal inhibition and decussation of the cell axon, stimulation on one side of the body results in contraction of all the muscle on the contralateral side.

The demersal fish populations of the slopes of the Rockall Trough (250 to 3000m) have been sampled by a number of different types of trawl (Gordon & Duncan, 1985; Gordon, 1986). The diets of most species have been described (Mauchline & Gordon, 1980, 1983a,b, 1984a,b,c) and aspects of the trophic ecology discussed (Mauchline & Gordon, 1985, 1986). Rays were relatively uncommon in the early sampling but the more recent use of a Marinovitch semi-balloon trawl with mud rollers and chain on the footrope has increased catches. This paper describes the distribution and diet of 12 species of ray from the slopes of the Rockall Trough.

Vance (1973a, b) argued that among the possible range of developmental strategies available to marine invertebrates, only the extremes of obligate planktotrophy and obligate lecithotrophy are evolutionarily stable. Vance's model, relating reproductive 'efficiency' to egg size (in terms of energetic content), predation rate, and prefeeding (lecithotrophic) vs feeding (planktotrophic) larval periods, has been a source of much discussion and debate since its inception (e.g. Underwood, 1974; Vance, 1974; Christiansen & Fenchel, 1979; Obrebski, 1979; Williams, 1980; Jablonski & Lutz, 1983; Strathmann, 1978, 1985; Todd, 1985). Subsequent publications have continued to dwell mainly on potential selective factors and the extremes of larval developmental type (i.e. obligate planktotrophy or obligate non-pelagic lecithotrophy). For the most part, these investigations have ignored questions concerning how a transition from one larval type to another would be accomplished in morphological and functional terms. Nonetheless, the consensus persists that small eggs and planktotrophy are the primitive (or ancestral) condition, and that lecithotrophy is the more advanced evolutionary derivative (see Strathmann, 1978,1985).

Surprisingly little is known about the influence of salinity on embryo development in crustaceans despite its obvious potential importance to species which breed in inshore estuarine waters. Evidence from the literature is that embryo salinity tolerance may differ from that of later stages in the life history (e.g. Kelley & Burbanck, 1976; Rosenberg & Costlow, 1979; Hartnoll & Paul, 1982; Jones & Simons, 1982; Wear et al., 1986) and such differences may impose restrictions on distribution. Wittmann (1984) referring to mysids, emphasised that an understanding of incubation period and factors influencing it "appears to be a key factor for the understanding of variations in the length and timing of the breeding season, age of maturity, frequency of broods, numbers of young per brood, egg size, and adult body size".

The long-standing hypothesis (Thorson, 1946, 1950; Mileikovsky, 1971; Jablonski & Lutz, 1983) that deep-sea invertebrates should reproduce by direct development or by non-feeding (lecithotrophic) larvae is beginning to fall in the light of recent data. Traditional reasoning maintained that planktonic food should be limiting at great depths, and that microscopic, ciliated larvae should be incapable of migration to the euphotic zone. However, in recent years, planktotrophic larvae of two deep-sea gastropods have been collected in surface waters, and planktonic larval development has been inferred from shell morphology and chemistry in several other species (Bouchet & Warren, 1979; Killingley & Rex, 1985). Planktonic larvae have also been collected in the water column of the deep sea (Berg et al., 1985; Smith, 1985; Berg & Van Dover, 1987), particularly near hydrothermal vents. Relatively diverse benthopelagic plankton populations relying primarily on suspended detritus for food are now known from the benthic boundary layer of the deep sea (Wishner, 1980a, b; Gowing & Wishner, 1986). Thus, it is increasingly apparent that planktotrophy may be a common option for deep-sea larval development.

Perkinsus marinus, a protozoan parasite of oysters, is an important cause of oyster mortality in the Gulf of Mexico and along the south-eastern coast of the United States (Hofstetter, 1977; Quick & Mackin, 1971). Infections are patchily distributed on many reefs, often with uninfected oysters adjacent to infected oysters. The primary mechanism of transmission from one oyster to another is through the water (Ray, 1954; Mackin, 1962; Andrews, 1965). Because dilution rapidly reduces the number of infective elements below the dosage required to initiate new infections (Andrews, 1979), transmission is most efficient over very short distances and declines rapidly within a few metres of the source.

Occasional small specimens of herring have, since at least 1875, been taken by Plymouth anglers in winter under harbour lights. In 1937 larger herrings appeared, and a specialised rod fishery developed which continued, apart from the war years, until 1953, when it collapsed suddenly.