Nephrops norvegicus (Linnaeus, 1758) is a valuable commercial shellfish species. UK landings in 1986 totalled 25,515 tonnes with a market value of over £39 million. It is difficult to estimate stock abundance using trawl surveys because of seasonal changes in the availability of females which tend to remain in their burrows whilst berried (ovigerous) (Chapman, 1980). An alternative method is to assess the number of mature adults in the stock using fecundity data and abundance estimates of larvae derived from plankton surveys (Thompson et al., 1986; Nichols et al., 1987). Estimates of the age of larvae are necessary to enable daily and seasonal production rates to be calculated from abundance data. Water temperature causes considerable variations in the development rate of planktonic Crustacea (Winberg, 1971; Thompson, 1982), and reliable estimates of larvae production therefore require knowledge of the relationship between stage duration and water temperature. This paper describes the results of laboratory experiments carried out from 1984 to 1986 to study this relationship in the three free-swimming stages referred to as zoea I-III by Farmer (1974). Stage IV is generally accepted as the first juvenile stage (Anger & Püschel, 1986). The morphology and general biology of Nephrops larvae are described by Farmer (1975) and Nichols et al. (1987); these authors comment on the scarcity of data concerning the effect of temperature on stage duration.

One of the more recent aims of deep-sea biological investigations has been to assess the rates and processes involved in the recolonisation of deep-sea sediments by the in situ fauna (Grassle, 1977; Desbruyères etal., 1980, 1985; Levin & Smith, 1984). The spur to such initiatives has been the prospect of deep-sea mineral exploitation and the dumping of radioactive and other chemical wastes (Desbruyères etal., 1 985), in addition to the testing of hypotheses about deep-sea community regulation (Levin & Smith, 1984; Smith, 1986). These experiments have shown that perturbated or defaunated sediments incubated for periods of several months are readily recolonised by deep-sea animals, although the process is much slower than in comparable shallow-water situations (e.g. Levin, 1984; Zajac & Whitlach, 1982a, b). Furthermore, the resulting community of colonists may be quantitatively and qualitatively different from the ‘background’ fauna (Grassle, 1977; Levin & Smith, 1984). Similar experiments have examined the effect of large ‘food-parcels’ on the in situ sediments and fauna (Smith, 1986), and a review of the responses of benthic faunas to disturbed sediments has been published by Thistle (1981).

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 three lobed paragnath of Palaemon serratus (Pennant) contains numerous rosette-type tegumental glands often arranged in clusters of up to ten glands. Each gland is made up of around ten cells most of which stain deeply with toluidine blue and whose contents have a reticulate appearance in electron micrographs. One, or occasionally two, cells stain faintly and have a fine granular appearance in electron micrographs. The central region of each gland contains the main drainage duct together with feeder canals from the vesicular storage areas. The actively secreting region of each cell is peripheral and typified by abundant rough endoplasmic reticulum and Golgi apparatus. There are nerves adjacent to the glands and their contents are probably discharged in response to a food stimulus. The structure and possible function of the glands are discussed in relation to those of other species The secretions could act as a lubricant and as a binding agent to aid in the ingestion of particulate food. There is no evidence for any direct digestive function.

Corophium bonnellii (Milne-Edwards) has been suspected of being parthenogenetic for more than fifty years (see Crawford, 1937) and this suggestion has been supported by recent breeding experiments (Moore, 1981). Many thousands of specimens have been examined by taxonomists and ecologists from a wide geographical area in both hemispheres, yet only Toulmond & Truchot (1964) have claimed to have found a male. No description or figures were presented by Toulmond & Touchot (1964) to support their contention.

Populations of Odostomia eulimoides Hartley were sampled from mussel beds on an exposed rocky shore at Preghane Point on the south coast of Ireland from April 1984 to October 1985 and from sublittoral farmed mussels at Bantry Bay on the south west coast of Ireland from March to October 1986.

At Preghane Point O. eulimoides had a area-annual life cycle with summer-autumn recruitment. Peak recruitment occurred from May to July in 1984 and from July to September in 1985. This aphasic recruitment was explained by the lower mean adult shell height recorded from April to June 1985 than in these same months in 1984.

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.

Many techniques have been devised to overcome certain problems encountered when narcotising actiniarians. From these a few have been selected as being at least partly successful. Further modifications to these narcotising methods have been introduced in order to block more effectively the nervous pathways responsible for secondary contraction reactions. Until now, perfectly expanded specimens have been achieved largely by chance. This paper records experimental results and arising problems as a contribution to a better understanding of the process and a more consistent rate of success.

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.

Previous field studies have recorded yearly variations in fecundity of 40–60% in similar sized plaice, and an experiment was conducted to investigate whether these changes could be generated, in the laboratory, by feeding plaice different levels of ration. One group of plaice was fed at a rate of about 2–2.3% of wet body weight per day, and a second group was fed initially 0.5% and later 1.8% per day. The experiment lasted for a period of 406 days.

Of those fed on the lower ration, 39% produced no granular oocytes, whereas all fish on the higher ration produced granular oocytes. A comparison between the two groups, of those which did produce granular oocytes, found that the better-fed fish had 59% more granular oocytes, but the differences were less pronounced for the smaller, mature fish. Numbers of resting oocytes are also recorded.

The results suggest that food level can significantly affect fecundity, and also revealed a new mechanism for regulation of fecundity in the plaice. The lack of granular oocytes was not due to atresia, but to an early decision not to proceed with gonad development; whether this is of practical significance for the population of plaice in the wild is not yet established.

It is well established that the lipid content of the herring Clupea harengus from the waters around the British Isles and Ireland undergoes a marked seasonal cycle, being highest during the summer months of active feeding and lowest after a winter fast (Wood, 1958; lies & Wood, 1965; Lovern & Wood, 1937; Molloy & Cullen, 1981; Wallace, 1986). In the case of spring-spawning herring, the minimum lipid content coincides with the spawning period and the depletion of lipid over winter corresponds with the development of gonads (Lovern & Wood, 1937).

The effects of nutrient enrichment of natural water bodies range from small increases in plant biomass and production, to gross deterioration of water quality. The input of nutrients (e.g. nitrogen and phosphorus) to the sea off NW Europe (especially the North Sea) has increased dramatically over the last three or four decades (Folkard & Jones, 1974; Bennekom et al., 1975; Postma, 1978; Cadee, 1986a) but there is uncertainty about the effects on the ecosystem. One possible effect might be to induce changes in the phytoplankton community. Such an effect has been reported for the North Sea, where increases in flagellate algae have been observed (Gieskes & Kraay, 1977; Postma, 1985; Cadee, 1986b; Batje & Michaelis, 1986). Phaeocystis is one such alga, and its purported involvement in the formation of large quantities of foam, observed on European beaches (Batje & Michaelis, 1986; Weisse et al, 1986), together with evidence that the alga is a source of atmospheric sulphur compounds (Barnard et al, 1984) (with implications for atmospheric acidity), has attracted particular attention and concern

A new species of free-living marine nematode, Terschellingia gourbaultae sp. nov., from the Tamar estuary, south-west England, is described and illustrated. This species has also been recorded from Brittany, France. T. daviger, sensu Gerlach (1963) nec Wieser (1956) is a junior homonym and is re-named T. maldivensis sp. nov. Five Terschellingia species including the new species are distinguished by their lack of a distinctly offset, rounded oesophageal bulb; a table and figures are given to aid identification of these species.

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.

The progress of the copepod Mytilicola intestinalis Steuer from obscurity in Mediterranean mussels, Mytilus galloprovincialis, to notoriety as the scourge of European blue mussels, M. edulis, has been well documented (e.g. Lauckner, 1983). However, a reputation as a pest in a commercially important species is not easily overturned and operators in the economic sphere must be expected to proceed with circumspection where their livelihoods are.at stake. In the UK, Parliamentary Orders still control the deposition and movements of seed shellfish in the attempt to contain the spread of the copepod.

The common dogwhelk (Nucella lapillus) is a dioecious species. However, on exposure to low concentrations (<1 ng I-1, Gibbs et al., 1987) of tributyltin (TBT) females develop certain male sexual characteristics, notably a penis and vas deferens. This phenomenon, first reported by Blaber (1970) in dogwhelks from the Plymouth area, and later termed 'imposex' (Smith, 1981), is now recognised as the most sensitive and straightforward way to identify contamination of coastal areas by TBT. The degree of imposex may be readily quantified as the relative penis size index (RPSI), which expresses the relative bulk of the penes in females and males from a given sample. It is calculated as (mean cubed female penis length/the mean cubed male penis length) x 100% (Gibbs et al., 1987). Gibbs et al. (1987) have examined the development of imposex in greater detail, and have divided the process into six stages (known as the vas deferens sequence, or VDS) based upon the degree of development of the vas deferens and penis in the female animal. This classification enables an assessment to be made of the reproductive ability of an animal. Stages 1 to 4 show a progressive development of the penis and vas deferens. At a VDS of 5, vas deferens tissue proliferates over the opening of the reproductive tract, blocking it, and subsequently causing sterility due to the inability of the animal to release egg capsules. Aborted egg capsules then gradually accumulate in the capsule gland (stage 6). The vas deferens sequence index, VDSI, is the mean VDS in a given sample of females.

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

Variations in dry body weight in the Stage V copepodite, associated with the development of the winter generation of Calanus finmarchicus (Gunnerus) in the Firth of Clyde each year were observed from 1978 to 1982, during early October and the middle of January.

The Stage V copepodite was dimorphic with respect to body size. Body weights of freeze-dried specimens were measured and form was distinguished using the prosome length. Allometric relationships of the dry weight to length in the two forms were similar, and stable between autumn and winter. From the mean of estimates for all collections, dry body weights of individual Stage V copepodites were proportional to the cube, approximately, of prosome lengths. Proportional coefficients were seasonally variable, but on all occasions these were greater for the large than the small form. Variations in dry weight were directly associated with the distinction between forms in body volume.

Collections from October and January encompassed the period between the end of maximal Copepodite V recruitment and the onset of adult recruitment to the winter generation. Over this period, however, the dry body weight in all years decreased relative to length in Copepodite Stage V. This decrease, on average, was by 17% and 23% in the large and small forms respectively. Monthly collections from one population were used to examine these patterns in relation to the development of gonads. Stage V copepodites of both forms were increasing in dry weight during October, but from November were losing weight continuously. Maturation in the majority of these individuals was restrained throughout autumn, abruptly accelerating in winter.

It is now well established that there are several species in the group of rough periwinkles inhabiting European rocky shores. The usual consensus agrees on four, namely Littorina saxatilis (Olivi), Littorina arcana Ellis, Littorina nigrolineata Gray and Littorina neglecta Bean. The first two species are particularly difficult to distinguish in the field and have received much attention. Recent work indicates that the ovoviviparous L.saxatilis is a very variable species living in a wide range of habitats (e.g. Janson, 1985) and that, although it is close to the oviparous L. arcana in shell morphology and in genotype, the two are separate species (Ward & Warwick, 1980; Ward & Janson, 1985), and not reproductive morphs of the same species.

The marine mussel, Mytilus edulis, is a widely distributed bivalve, especially abundant on wave washed exposed rocky shores (Lewis, 1964). Investigations on the reproductive and settlement cycles of M. edulis in Irish waters have concentrated to date on sheltered shore populations (Wilson & Seed, 1974; Seed & Brown, 1975; Rodhouse et al., 1984; McKenzie, 1986). An exception to this is a brief account of settlement in Bantry Bay (Cross & Southgate, 1983). Elsewhere in Europe, investigations on the biology of exposed-shore mussels is restricted to the extensive studies of Seed (1969) on the north-east coast of Britain.