The swimbladder of teleost fishes is a gas-filled sac which serves primarily to make the fish neutrally buoyant in sea water, but occasionally assumes other functions. The gas contained in the swimbladder is largely oxygen, at a pressure very close to the external hydrostatic pressure. The difference in gas partial pressure between the gaseous contents of the swimbladder and the blood and tissue fluids is large in fishes living at any considerable depth, for the hydrostatic pressure increases about 1 atm with each 10 m depth, while the partial pressures of gases in sea water and body fluids are relatively independent of depth and together give a pressure of only about 1 atm. The difference in partial pressure of oxygen alone across the wall of the swimbladder of a fish living at 3000 m depth is close to 300 atm.

In the family Alepocephalidae there are ca. 19 valid genera (Markle, personal communication). Whilst luminescence has never been observed, there are four genera, Xenodermichthys, Photostylus, Rouleina and Microphotolepis, which contain species bearing structures that have been interpreted anatomically as photophores (Herring & Morin, 1978). Among these four there is a remarkable diversity of photophore structure. The photophores of Xenodermichthys and Photostylus are similar in having well developed central cores (reddish violet in Xenodermichthys) and reflector layers, yet those of Xenodermichthys are sessile whilst those of Photostylus are borne on stalks (e.g. von Lendenfeld, 1887; Best & Bone, 1976). Not all species of Rouleina have light organs but where they are present they are sessile. Photophore structure of Rouleina has been examined only in R. maderensis Maul and was found there to be rather degenerate in adults (Markle, 1978). The light organs of Microphotolepis multipunctata Sazanov and Parin differ yet again in being scale covered, which contrasts with the naked photophores in the other three genera (Sazanov & Parin, 1977). The abundance and distribution of photophores in adults also varies with genus and species. Thus in Microphotolepis and Xenodermichthys they are extremely numerous and regularly arranged but in Photostylus they are few and less ordered (Günther, 1887; Beebe, 1933; Sazanov & Parin, 1977). In different species of Rouleina photophores may be relatively abundant and regularly arranged or few in number without such regular pattern (Maul, 1948; Uyeno & Kishida, 1977; Markle, 1978).

There is some controversy about the strength of the stock of mackerel in the Celtic Sea and off the coasts of Cornwall and Ireland, and it is difficult to find out if the numbers of mackerel in this area have fluctuated in the past (Johnson, 1977; Lockwood & Johnson, 1976; Lockwood, 1978; Coombs, Pipe & Mitchell, 1977,1979, 1980). The earliest complete survey of the south-west spawning grounds was made in 1937–9 (Steven & Corbin, 1939; Corbin, 1947) and was principally designed to show the seasonal and geographical pattern, not provide a basis for stock evaluation. Nevertheless, this survey is the only information we have about the breeding of mackerel in the days before the war when fishing was performed with drift-nets and lines, a period when we can assume exploitation was very much less intense than today when trawls and purse-seines are used. Attempts to use the 1937–9 data for estimation of the pre-war stock have been regarded as giving unsatisfactory results (Walsh, 1976). The data from the 1937–9 surveys were defective because we did not know the influence of the depth of fishing of the nets in relation to the vertical distribution of the eggs, nor the efficiency and catching capacity of the nets for sampling eggs and post-larvae.

Opportunities for measurements on living Nautilus are rare, and such studies as there have been on its locomotion tend to treat it as primitive compared with modern cephalopod molluscs. But the few measurements we were able to make on a healthy captive Nautilus living for several months in the Monaco Aquarium reveal considerable sophistication in the control of swimming - particularly in the way the funnel operates - and that the system possesses neuromuscular properties that may be fundamental to cephalopods as a whole. The use of the shell for transmitting the pressure pulse and for the in- and out-movements of the body during jetting are, however, peculiar to this member of the group.

Cephalopod statoliths are paired calcareous stones which lie in cavities, the statocysts, within the skull. They have a form which, though variable, shows promise as a source of criteria for taxonomic and evolutionary studies. As a preliminary to more detailed studies, Clarke (1978) published a description of the form of a generalized teuthoid statolith, coined nomenclature for the various parts and gave a very brief survey of variation of statoliths within the living Cephalopoda. This nomenclature was used in a detailed description of fossilized teuthoid statoliths by Clarke & Fitch (1979). Here, descriptions of the statoliths of the living species Berryteuthis magister (Berry, 1913), Gonatopsis borealis Sasaki, 1923, Gonatopsis (Boreoteuthis) makko Okutani & Nemoto, 1964 and Gonatus fabricii (Lichtenstein, 1818) are given and the fossil Berryteuthis species described in outline by Clarke & Fitch (1979) is compared with B. magister. A statistical analysis of measurements of the statoliths of these five species has been made and the results are presented. This forms the first part of a general description of teuthoid statoliths and similar studies on the Ommastrephidae and the Loliginidae are in preparation.

Previous studies on cirral activity in thoracican cirripedes have established two basic patterns of feeding action. In the Lepadomorpha, the Verrucomorpha, and the chthamaloid and coronuloid Balanomorpha, prolonged cirral extension provides the basis for captorial feeding. The cirri are held extended and are used, individually or collectively, to capture small live prey. Investigations on these species have yielded no evidence of sustained rhythmic cirral activity as a component of food collection among a variety of species (Crisp, 1950, 1967; Southward, 1957, 1962, 1967; Mori, 1958, 1961; Southward & Southward, 1958, 1967; Barnes & Reese, 1959; Howard & Scott, 1959; Patel, 1959; Crisp & Southward, 1961; Southward & Crisp, 1965; Bieri, 1966; Jones, 1968; Stone & Barnes, 1973; Klepal & Barnes, 1975).

Intertidal estuarine barnacles suffer cyclic changes in salinity and temperature, the latter being most marked and often quite abrupt at the time of tidal immersion and emersion.

Scallops of the bivalve family Pectinidae are very valuable shellfish and the subject of various important commercial fisheries around the world. Most of these fisheries are at present dependent upon natural populations, which can fluctuate widely in abundance from year to year due to irregular recruitment and overfishing. In recent years there has been considerable interest in the possibilities of cultivating various scallop species and some success has been obtained in rearing larvae of Pecten maximus (L.) in the laboratory (Comely, 1972; Gruffydd & Beaumont, 1972). However, by far the most successful cultivation system developed for pectinids has been carried out for several years in Japan for Patinopecten yessoensis (Jay). Naturally produced spat settling on Collectors made from artificial materials are grown on to market size in cages in the sea or used to restock natural beds (Ito, Kanno & Takashashi, 1975; Querellou, 1975; Motoda, 1977).

The abundance of calanoid copepods in marine plankton and their importance as food for certain fishes has prompted numerous studies of their biology, including several concerned with fecundity (Marshall & Orr, 1952; Mullin & Brooks, 1967; Paffenhöfer, 1970). These studies, however, have all involved animals maintained on various diets in the laboratory: data for egg-production by Calanus under natural conditions in the sea are still needed.

To ensure the survival of the young of many animal species to the stage of independent feeding, biochemical energy in the form of lipid is stored within the egg. During a recent survey of Calanus helgolandicus (Claus) from the English Channel the level of lipid, mainly in the form of wax esters, in Stage V copepodids was found to be substantially greater than that in female adult stages (Gatten et al. 1979). The difference was particularly noticeable during spring periods when egg-laying was in progress. This observation indicates a major role for wax esters during the reproduction of Calanus.

The present study seeks to establish the fate of the lipid reserves in Stage V and female adult Calanus with particular emphasis on the extent to which the size of such reserves can be used as an index of the fecundity of this copepod.

Enclosures of various sizes and configurations have been employed to maintain natural planktonic communities and to examine their responses to pollutants (e.g. Menzel & Steele, 1978; Steele, 1979). Studies on feeding, growth, and mortality of larval fishes, at times conducted in conjunction with pollution experiments, have also been successfully conducted in large enclosures (Koeller & Parsons, 1977). Implicit in these and other comparable studies has been the expectation (or hope) that a balance could be achieved between the advantages and difficulties inherent in more traditional field and laboratory studies. Field studies offer the realism of working with the natural assemblage with its many interacting components and links, but also suffer the disadvantage associated with a turbulent and advective system, which generally makes the repetitive sampling of the same populations impossible. Laboratory studies reverse the balance; control and definition of the components are gained at the expense of realism. The use of large containers represents a hybrid approach characterized by a partial control over a moderately realistic ecosystem. In the ideal case, the use of large containers allows sufficient control to permit experimental manipulation of (and the testing of hypotheses concerning) planktonic assemblages which are sufficiently realistic to permit extension of the experimental results to the ‘real world’.

There is a long history of research on the ormer, Haliotis tuberculata L., in the Channel Islands. Stephenson (1924) was concerned with the reason for the diminution in the number of ormers off the shores of Guernsey and undertook a three months' investigation during the summer of 1923 and published brief notes on his results for further investigation. Tanner (1926) also made some brief notes on various aspects of the biology and ecology of the ormer which he said were based on 30 years' observation. In two reports (1929, 1937), Crofts dealt with aspects of bionomics, anatomy and early development of ormers with brief accounts of reproduction. Brehaut (1957) reported tagging experiments on the movement and growth of ormers and Forster (1967I gave more detailed information on these aspects, having earlier (1962) published a study on the quantitative measurement of the ormer population.

There are many Haliotis species which are widely distributed along the rocky coasts of temperate and tropical zones, most of them inhabiting the shallow sublittoral areas. Many of them form an important part of the fisheries industry in such countries as Japan, U.S.A., South Africa and Australia. In Guernsey, the Channel Islands, the ormer Haliotis tuberculata L. has been gathered as a local delicacy at low tide of good spring tides - locally known ‘ormering’.

Extensive tagging experiments have been undertaken at various places in the world for other species of haliotids, dealing with their growth and movement (Cox, 1962; Newman, 1966; Poore, 1972; Shepherd, 1973). For H. tuberculata, two tagging experiments, in which the growth and movement of sublittoral ormer populations were dealt with in detail, have been reported (Brehaut, 1958; Forster, 1967).

The present study has laid emphasis on the structure and growth of a shore population which has been the most important object of ormering to date.

Intertidal organisms are particularly prone to the effects of both crude oil and to the chemicals commonly used to disperse the oil, following an oil spill at sea (Smith, 1968). A large body of literature now exists on the lethal effects of crude oil and dispersants but little progress has been made towards elucidating the toxic mode of action of these chemicals, nor to understanding what effects they exert when present in sub-lethal concentrations. Since the gills of aquatic animals are generally the most delicate of the epithelia exposed to the environment, it is likely that they will be most prone to damage by pollutants. Whilst previous workers using light microscopy (e.g. Clark, Finley & Gibson, 1974; Blanton & Robinson, 1973) have reported gross damage to the gills of mussels and fish following exposure to crude oil, there was no information available on the nature of the cellular damage at the ultrastructural level. In this study, we describe the nature of the lesions produced in the gills of the common intertidal limpet Patella vulgata following exposure to the water soluble fraction of North Sea crude oil and to the dispersants BP 1100 X and BP 1100 WD. A description of the ultrastructure of normal gill plates of Patella has been published previously (Nuwayhid, Davies & Elder, 1978).

An intensive study of the benthos at six deep-water stations in the Gulf of Gascogne was undertaken by the Centre Océanologique de Bretagne, Brest (during 1972–4) (Laubier & Sibuet, 1977, fig. 1). These stations were repeatedly sampled with a variety of gear during seven different ‘Biogas’ cruises, and over 1900 sipunculans belonging to 16 species including one new to science were collected. Table 1 lists these species and their abundance at the six stations. Specific station data on the samples can be obtained from the authors.

The ubiquitous nature of sipunculans is well documented by this work. Of the 72 dredge hawls made, 86% contained sipunculans, while 80% of the 54 trawl collections yielded sipunculans. Sample CP 01 with 165 sipunculans belonging to five species was the richest collection. The efficiency of the collecting gear and richness of the fauna is indicated by the fact that 24% of the individual collections yielded four or five species while 12% yielded 6–9 species, compared with the usual 1–3 species often collected. At Sample DS 62 a single haul yielded nine out of the 12 species at Station 1.

The following section contains brief comments on the species and their distribution. Full descriptions of these species and additional references can be found in Stephen & Edmonds (1972) and Cutler (1973). The subgenera of Golfingta follow Cutler & Murina (1977) and Cutler (1979).

The faunas of volcanic islands must necessarily be introduced, and more recent introductions can be recognized by the patterns of their distributions. This is obvious in the Canary Islands, where we have spent 30 days studying distributions of Spirorbidae. We now regard these as a distinct family following Pillai (1970). We sampled all the major islands, by shore collecting and diving to about 10 m, and on almost all we found nine Mediterranean species, namely Protolaeospira striata (Quiévreux, 1963) and the eight opercular incubators (species of Pileolaria and Janua) that have been recorded from both Marseilles (Zibrowius, 1968) and Chios (Bailey, 1969).

Abra alba and Abra tenuis are closely related marine bivalves. They both inhabit similar types of sandy-mud sediments but they prefer different localities. The smaller A. tenuis is found in a few scattered intertidal mudflats, whereas A. alba is more widely distributed and in great abundance in the coastal waters of north-west Europe. The latter can be found at any depth between low-water mark and 80 m (Tebble, 1966; Ansell, 1974) and often forms the dominant species of shallow water benthic communities.

The reproductive cycle of the two species has been studied and compared as a part of a wider ecological investigation. There is minimal literature concerning the reproduction of A. tenuis but A. alba has received a lot of attention, because it forms a major source of food for flatfish. However, most of the earlier investigations are confined to the time that spawning occurs with the evidence derived from either the time of the year that larvae appear in the plankton (Lebour, 1938; Jorgensen, 1946; Fosshagen, 1965; Muus, 1973; Rasmusen, 1973), or the time of the year that juveniles first appear in the bottom samples (Orton, 1924; Ford, 1925; Stephen, 1932). The inadequacy of such indirect methods has been discussed by Seed (1969,1975, 1976). Ansell (1974) derived the reproductive cycle of A. alba from seasonal changes in the biochemical composition. In the present investigation, histological techniques have been used, since they are considered to offer the most reliable information about the reproductive cycle (Seed, 1969, 1975, 1976).

Production rates and production/biomass ratios have been estimated for a large number of macrobenthic species (Hargrave, 1977; Robertson, 1979). The usefulness of such estimates is limited by a lack of information on their temporal and spatial stability; we are aware of only one study (Sarvala, 1980) in which production has been estimated for more than one year. The present study investigates the stability of the production (P), biomass (B) and P/B values of two polychaete species, Nephtys hombergi Savigny and Ampharete acutifrons (Grube), over a 5-year period.

Bioassays designed to test the effect of single or some combination of environmental factors or pollutants on aquatic organisms are usually performed in constant levels of the imposed conditions and commonly in static rather than flowing water. The reason for this is usually one of convenience and practical simplicity and the results are valid for the set of conditions imposed. However, since aquatic organisms are rarely exposed to constant and static conditions, the results of such tests cannot with confidence be extrapolated to field conditions. This is particularly true in the case of estuarine organisms for which, change is the rule.

Whilst there have been a number of fundamental studies illustrating the effects of Earth's rotation on the flow around submerged obstacles (Hogg, 1973) and islands (Longuet-Higgins, 1969) there appear to be relatively few studies that include both non-linear advective and frictional effects (Huthnance, 1972), and few were found describing the stagnation region that develops in the lee of the flow due to the advection of vorticity generated by the frictional stress associated with a beach gradient (Pingree & Maddock, 1979). In this paper some rotational flow patterns that can develop around an island due to these effects are examined using a numerical model and an overall attempt has been made to illustrate the possible use of numerical models as a tool for theoretical investigations in areas of study that until recently have been exclusively analytical or experimental. An island is surrounded by a uniform beach gradient and the model illustrates how varying bottom topography modifies a steady flow due to both frictional and Earth's rotation effects. Only non-oscillating flows with steady wakes are considered here so that the vorticity sources and sinks can be examined as simply as possible. Stagnation regions due to frictional effects are known to be important in determining sediment deposition and the effects of the Earth's rotation may result in increasing asymmetry in sediment distributions (Johnson, Vogt & Schneider, 1971).

The cirratulid polychaete Cirriformia tentaculata (Montagu) may be found in gravelly mud or sand often beneath large stones in pools between tide marks. It is usually associated with reducing conditions indicated by blackened mud or sand and the distinctive odour of hydrogen sulphide. It occurs also in crevices that retain stagnant water at low tide. The worm does not make a permanent burrow but lies in different postures to enable the branchiae and feeding tentacles to be extended on to the surface, where they are bathed by the overlying water. The mucus-lined burrow is not irrigated.

Cirriformia tentaculata encounters two respiratory problems. When covered by water the branchial filaments can take up oxygen which is then circulated by means of the well-developed vascular system with blood containing haemoglobin in solution. While the branchiae may lie in a well-oxygenated medium the main body of the worm lies in a highly reducing substrate. The sediment immediately surrounding the worm is commonly black and there is no oxygenated layer as occurs in burrows which are irrigated and provide an envelope separating the animal from a potential oxygen-sink. If exposed by the tide the branchiae are withdrawn or clump together and cannot function effectively. Even when covered by the tide the branchiae can be rapidly with-drawn, presumably to avoid loss by predation, and under all these conditions the animal must experience hypoxic or anoxic conditions of varying duration of up to several hours.

We have examined the ability of Cirriformia tentaculata to maintain oxygen uptake under decreasing oxygen tension, the oxygenational properties of the haemoglobin, the oxygen capacity and blood volume.