When scanning electron microscopy became integrated with X-ray micro-analysis, it became an easy matter to localize an object and perform a semi-quantitative elemental analysis of atoms of atomic number 11 or higher using an energy dispersive spectrometer. This technique is used in the present study to determine the chemistry of the statoliths of eight hydromedusae, two scyphomedusae, one cubozoan and a ctenophore with respect to their comparative biomineralization and the relationship of the mineral to their taxonomy.

A spermatophore is defined as a capsule of albuminous matter containing a number of sperm. Among opisthobranchs the families Retusidae, Philinoglossidae, Bullidae, Atydae and Runcinidae are all said to possess a copulatory apparatus which stores sperm and also forms spermatophores (Ghiselin, 1966). Relatively little information exists concerning the structure of the copulatory apparatus or the spermatophore in these groups and practically nothing is known about the copulatory behaviour of the animals and the fate of the spermatophore (Perrier & Fischer, 1914; Ghiselin, 1963, 1966; Thompson, 1976;Beeman, 1977). This paper will focus on the structure of the spermatophore of the cephalaspid Runcina (Kress, 1977). The formation of sperm occurs in the hermaphroditic glands, in a more central position than that of the eggs. These autosperm leave via the common genital aperture which is located laterally to the gills. They travel by means of strong ciliary action, through a seminal groove to the male copulatory apparatus on the right of the mouth. The sperm then moves through the penis and the prostate into a storage sac, the seminal vesicle. For copulation, these sperm are packed into a spermatophore which should presumably be introduced into the common genital aperture but which may be found attached to the mantle or foot, even to animals not yet sexually mature. We have taken this opportunity to study the spermatophore which otherwise might not be easily detected.

INTRODUCTION

It is apparent, in a review on the decapod hepatopancreas (Gibson & Barker, 1979) that there is some consensus of opinion that the epithelium consists of E-, R-, F- and B-cells and M-cells (Al-Mohanna, Nott & Lane, 1985). Also, it is agreed that the gland produces enzymes and absorbs, digests and stores nutrients and excretes waste material. However, the apportionment of these functions to the different cells and the descriptions of the cytological processes involved are variously explained. Thus, the activity of proteases and amylases has been demonstrated in the secretion produced by the gland but the source of these enzymes is attributed to different cells and various modes of secretion are proposed. Also, no secretion granules of the zymogen type have been seen.

There are probably two main reasons for the inconsistent interpretation of the activities of the cells. First, the different stages of the feeding and moult cycles are not taken into account and both these affect the cytology of the gland. Second, some of the functions have been deduced from observations of the fine structure without any experimental treatments to demonstrate more directly the processes involved. In the present work all the animals are taken at the same moult stage and observations are made throughout the feeding cycle. Also, aspects of the function are studied with markers which are administered in the diet and injected into the blood. The activities of hydrolytic enzymes associated with the different epithelial cells have been studied but these will be the subject of a separate publication dealing with the cytochemistry of the digestive processes.

In previous papers (Broertjes, de Waard & Voogt, 1984a, b) we reported on the presence of vitellogenic substances in the starfish Asterias rubens and described their separation into three fractions, called 2, 3 and 4, which were isolated and purified. The interrelationship between these fractions was discussed and evidence was given that fractions 3 and 4 may be derived from fraction 2.

In recent years several workers have postulated the occurrence in a number of coastal animals of endogenous behaviour and physiological rhythms of semilunar periodicity (see Naylor, 1982). However, only a few of these long term rhythms have been demonstrated as free-running cyclical behaviour over long periods of time in constant conditions. For example, the supra-littoral amphipod Talitrus saltator (Montagu) has been shown to express semilunar variations in daily locomotor activity over three cycles of neap/spring tides during 46 days in constant conditions in the laboratory (Williams, 1979). In contrast, in the mid-shore sand-beach isopod E. pulchra (Leach) semilunar variations in swimming behaviour (Fish & Fish, 1972; Alheit & Naylor, 1976) and of respiration (Hastings, 1981a) have so far been demonstrated only in isopods collected at various stages of the neaps/springs cycle of tides and recorded for a few days in the laboratory. It, therefore, still remains to confirm unequivocally in Eurydice, and in many other forms, which appear to show semilunar periodicity, that such rhythmicity is expressed as a free-running rhythm over long periods of time in constant conditions.

INTRODUCTION

The heart of tunicates is of physiological interest for several reasons: it is a simple peristaltic tube; it lacks valves; and the direction of the contractions changes periodically thus reversing the direction of blood flow. The phylogenetic importance of tunicates, being invertebrate chordates, also make physiological details of interest.

A comparative study of Chorda filum populations from the British Isles (S 34‰) and the Baltic coast of Finland (S 6‰) has revealed differences in response by live adult thalli to treatment for 2 h with sea water of different salinities. Water uptake and loss by thalli differed significantly in salinities of х o‚ х 1/6, х ⅓ and х 1 ( = 34‰). British material showed severe cell disruption in freshwater whereas Finnish material did not. Killed thalli also behaved differently, British material showing little response to salinity treatment but Finnish plants continuing to react much as live tissues.

Anatomical differences between populations were also observed, cortical cells in Finnish plants being significantly smaller than their British counterparts. Diaphragms traversing lumens of British material were simple, entire structures, but those in Finnish plants were deeply dissected and complex in organization.

It is postulated that Baltic Chorda may have undergone a process of evolutionary divergence in response to its changed saline environment.

INTRODUCTION

Chorda filum (L.) Stackh. is one of several species of north Atlantic Phaeophyceae to be found in the inner Baltic Sea and Gulf of Bothnia; its geographical limit being associated with sea water salinity of approximately 4‰, (Waern, 1952; Hällfors et al. 1981). This species has been studied by Norton & South (1969) and South (1966) who traced the development of gametophytes and early sporophytes in culture media of different salinites. Although their cultures had been established from British material only, they felt able to argue from their results that the Baltic population did not constitute ‘… a different physiological strain specially adapted to the extreme environmental conditions prevailing there’.

Information regarding spawning grounds of the Atlantic herring Clupea harengus Linnaeus has been based mainly on the collection of spawning fish, newly hatched larvae, or the presence of eggs within the stomachs of predators (Postuma, Saville & Wood, 1977). This type of evidence indicates general areas of spawning, rather than accurately delineating the spawning grounds. Though samples of spawn have been obtained from several localities in the North-East Atlantic (Ewart, 1884; Runnström, 1941; Fridriksson & Timmerman, 1951; Bolster & Bridger, 1957; Parrish et al. 1959; Hemmings, 1965; Bowers, 1969; Anthony, Sauskan & Sigaer, 1970), few quantitative studies of individual grounds have been made. In consequence, little is known of the factors influencing the selection of grounds by Atlantic herring, the shape of these grounds and egg distribution within spawning areas.

Elasmobranchs, unlike teleosts, do not possess otoliths or scales suitable for age determination. Various skeletal structures of elasmobranchs have been used in an attempt to find a reliable ageing technique. These include the centra of Raja fusca (Ishiyama, 1951). R. eglanteria (Daiber, 1960), R. erinacea (Richards, Merriman & Calhoun, 1963) and Cetorhinus maximus (Parker & Stott, 1965). Yokota (1951, 1952) has described annual growth increments on the claspers of various elasmobranch species. Stevens (1975) made vertebral ring counts in the blue shark, Prionace glauca L. More recently Jones & Geen (1977a,b), using X-ray spectrometric analysis, have examined the vertebral circuli of dogfish found in British Columbia waters. Methods of age determination, using the spines of the spurdog (Squalus acanthias L.) have been described by Kaganovskaia (1933, 1937), Bonham et al. (1949) and Aasen (1961). All these authors assumed that the more or less regular series of dark bands or ‘rings’, extending from a white pigment-free base of the enamel to near the tip, were annual. Holden & Meadows (1962), on the basis of the internal and external features of the spines, concluded that the dark bands did represent annual growth increments. In particular, they argued that the dark bands were laid down during the winter when growth would be slowest, whereas the faster growth in the summer was represented by the light bands. Holden & Meadows (1962) identified several conditions, e.g. birth, double, false and spawning rings – that made interpretation of the ring structure and subsequent age determination difficult.

INTRODUCTION

In the deep oceans where the water depths are in excess of 4000 m the benthic environment is widely separated from the productive euphotic zone and there is an exponential decline in pelagic biomass with increasing depth (Vinogradov, 1968; Wishner, 1980; Angel & Baker, 1982). The sea-bed acts as a sediment trap stopping the downward drift of particulates. Here resuspension and biological and geochemical processes in the benthic boundary layer cause enrichment of the waters above the sediments. Wishner (1980) has noted some of the evidence for near-bottom increases in phosphorus, nitrogen, ATP and sediment resuspension in the deep sea. In parallel with this enrichment and probably related to it, the pelagic macroplankton biomass is increased, at least to distances up to 100 m off bottom (Wishner, 1980; Angel & Baker, 1982). This suprabenthic zone seems to be inhabited by a distinct community of nektonic and planktonic species quite different to that inhabiting comparable depths in the abyssopelagic zone. Marshall & Merrett (1977) reviewed what was known of this community, with special reference to the fishes. Grice & Hulsemann (1970) and Grice (1972) have described new suprabenthic copepod species and Angel & Baker (1982) recorded an entirely novel pelagic ostracod fauna of 25 new species in a 5–20 m off bottom haul at 20°N, 21°W in 4005 m of water.

The reproductive morphology and larval development in Spionidae has been dealt with extensively by Soderström (1920), Hannerz (1956), Orrhage (1964). Simon (1967), Blake (1969) and Rice (1980). The family shows a considerable variation in gamete morphology, modes of sperm transfer and types of larval development. One might also expect variability in features of the life history patterns, such as the life span, reproductive age, reproductive cycles and fecundity, both between and within species.

Previous population studies on spionids include the work on populations of Polydora ciliata (Johnston) (Dorsett, 1961); (Daro & Polk, 1973), on populations of Scolelepis squamata (Müller) (Joyner, 1962); (Richards, 1970), on a population of Scolecolepides viridis (Verrill) (George, 1966) and on a laboratory reared population of Malacoceros cf. fuliginosus (Guérin, 1973). The present paper is an attempt to analyse the patterns of life history as they appear in littoral populations of Spio martinensis Mesnil, Polydora ciliata (Johnston), Pygospio elegans Claparede and Malacoceros fuliginosus (Claparède) at localities in N. E. England. The main features considered here are the changes in the size (age) distributions, the annual cycles of reproduction, the output of offspring and population density changes.

The Spio species in the population at Black Middens, North Shields, which is referred to S. martinensis Mesnil (1896) in this paper, was previously referred to S. filicornis (Müller, 1776) by Brady (1943). This species is identical to Mesnil's species, both in morphology and with regard to known biological features, while S. filicornis differs from it morphologically and its distribution pattern (Hannerz, 1956; Rasmussen, 1973; Wolff, 1973, Gudmundsson, in preparation).

A major contribution to our understanding of the distribution and taxonomy of echinoids in British waters was made by Mortensen (1927, 1928–1951). Many earlier qualitative investigations (e.g. Süssbach & Breckner, 1911; Brattström, 1941) which dealt only with limited areas, were combined in Mortensen (1928–1951) to produce an overall assessment of the North Sea echinoid fauna.

In his discussion paper Ursin (1960) synthesized findings from his 20 year grab sample survey with the work of others to produce a valuable quantitative analysis of the echinoids of the central North Sea (54–5 8° N).

In recent years (1977–1983) participation on demersal fish surveys in the North Sea has enabled the distribution and population structure of the macroepibenthic component of the water column to be recorded (Dyer et al. 1982, 1983; Cranmer, Fry & Dyer, 1984).

Although this present study has added no new echinoid species to the fauna it has given a detailed picture of echinoid distribution in the area.

The heart-body in Neoamphitrite figulus (Dalyell) forms a mass of tissue within the supra-oesophageal vessel almost occluding the lumen. The tissue forms a much-infolded cylinder enclosed by a basal lamina consisting of a fibrous reticulum through which the assembled haemoglobin molecules are discharged into the plasma (Dales & Pell, 1970). A function of both the heart-body and the extravasal (‘chloragogen’) tissue in polychaetes without a heart-body was established by biochemical analysis (Kennedy & Dales, 1958; Dales, 1963, 1965) to be the synthesis of plasma haemoglobin (erythrocruorin) or chlorocruorin. This was confirmed by electron microscopy (TEM) by Breton-Gorius (1963) in Arenicola, Potswald (1969) in Spirorbis, Dales & Pell (1970) in Neoamphitrite, Lattice, Myxicola, Megalomma and Sabella, and by Friedmann & Weiss (1980) in Amphitrite. It would appear that the same tissues also sequester phagocytosed materials (Braunbeck & Dales, 1984). Re-examination of this tissue by trans-mission electron microscopy (TEM) has extended our knowledge of the ultra-structure. Here we discuss these results in relation to the function of these tissues in the production of the respiratory pigments found in the plasma. Some heart-bodies of Terebella lapidaria L., Lattice conchilega (Pallas) and Cirriformia tentaculata (Montagu) have also been examined by TEM for comparison with that of Neoamphitrite figulus.

Eight species of the Gobiidae were recorded in weekly samples taken between July 1972 and June 1977 from the intake screens of Oldbury Power Station in the inner Severn Estuary. Buenia jeffreysii, Aphia minuta, Gobius paganellus and Gobius niger occurred infrequently and Crystallogobius linearis was only common in the late spring and summer of 1975 and 1976. Pomatoschistus microps, which peaked in numbers in the winter, increased in abundance each year between 1972 and 1977. The most numerous gobies were those belonging to the Pomatoschistus minutus complex which were separated into P. minutus and P. lozanoi only between June 1974 and July 1975. Seasonal trends in the abundance of these two species were similar, with elevated numbers occurring between July and September 1974 and in January 1975. Gonadosomatic indices and other data indicate that the decline in numbers after the latter month represented an emigration to spawning areas further down the estuary or in the Bristol Channel. Although P. minutus attained a larger body size than P. lozanoi, both these species and P. microps typically had a one year life cycle with only a small number of individuals surviving for a further few months. The fecundity of P. lozanoi, which ranged from 410–2453 (mean 1270), was lower than that reported for P. minutus in this and other studies. Analysis of stomach contents showed that the diet of both species was similar, consisting predominantly of gammarids and mysids. While both species were infected with Ligula intestinalis, the incidence of infection and the parasite index was greater in P. lozanoi than in P. minutus.

In marine crustaceans the polynuclear aromatic hydrocarbon benzo[a]pyrene undergoes changes mediated by benzo[a]pyrene mono-oxygenase (BPM), a cytochrome P-450 dependent enzyme system requiring molecular oxygen and NADPH as a cofactor: it has now been detected in several species (see O'Hara et al. 1982).

The common mussel inhabits an environment of fluctuating temperatures, salinities and water turbulence. To help cope with these stresses, mussels have evolved some extraordinary structural and biochemical adaptations. The production of the byssus is one such adaptation. The byssus is a complex array of threads and adhesive plaques that serves alternatively to attach the mussel to solid objects, to absorb shock, or to scale a vertical face (Waite, 1983 a; Price, 1983). Because of its location outside the animal's living tissues, the byssus cannot count on the same kind of repair and remodelling offered to structures within the animal. The byssus is thus confronted with two conflicting demands. One is to be a mechanically dynamic structure shielding the animal against the buffeting impact of waves; the other is to be chemically inert towards the hydrolytic action of sea water and microbial enzymes.

For centuries man has used lights to attract and concentrate fishes near the sea surface to aid their capture by nets or hooks (Ben-Yami, 1982). Underwater lights lowered into shallow seas are now regularly used to lure fish into set nets, large nets suspended beneath ships or into the vicinity of powerful pumps (Sidelnicov, 1981; Andreev, 1962; Nikonorov, 1969). Usually lights of more than 1 kw are used and such power requires a surface generator and strong insulated cable from the surface to the light. Although we know from these applications that some fish species are attracted by lights, the use of lights on trawls has not been developed for commercial exploitation or for research sampling. Perhaps such development has been discouraged by the safety problem and technical difficulties of providing electrical power on deck and handling heavily insulated conducting cable between the trawl and the generator. Lights have been used on commercial trawls with television in experiments to study fish reaction to trawls but such experiments were not concerned with finding the effect that lights might have on the quantity of fish caught and catches have not been analysed (A. Maclntyre, personal communication).

Risso's dolphin (Grampus griseus) (Cuvier, 1812) is not common off the coast of Devon although strandings are occasionally reported. Norman & Fraser (1948) noted that 45 had been stranded on the British coast over a period of 33 years and that these were concentrated in the south-west. While it is regularly stated that this animal eats squids exclusively the prey species have not been identified. In view of the variety of squids available to an oceanic mammal and the information its food can give on both the migration of the dolphin and the ecology of the cephalopods in its diet the stranding of a Risso's dolphin at Thurlestone Rock on 12 May 1983 provided an unusual and welcome opportunity to examine the animal and its food.

INTRODUCTION

The dust cart on the Isles of Scilly did not end its service at the local tip, over the cliffs at Deep Point on the eastern side of St Mary's on 14 October 1983. Instead it floated off and continued in service as a Lagrangian drifter, indicating the residual transport of water around the islands. As a hazard to shipping its position was given out as a navigation warning and it was allegedly sighted on the western side of Scilly. The interesting oceanographic question is whether the dust cart was (or would have had it not sunk) circumnavigating the islands in a clockwise or anticlockwise sense. Accordingly this experiment has been repeated using satellite tracked Argos drifting buoys, drogued with parachutes (~ 10 m diameter), and set at depths of about 15 m. The releases showed that the residual transport was clockwise around the islands. In one instance a drogue circumnavigated the islands in about 12 h (i.e. ~ one tidal period) at an average speed of about 100 cm s−1 (Fig. 1).

Coelomic fluid from the edible sea urchin Echinus esculentus (L.) has in vitro bactericidal activity against the marine pseudomonad, designated strain No. 111 (Wardlaw & Unkles, 1978). This particular bacterial strain was chosen because of its highly characteristic jet-black, agar-digesting colonies on marine agar plates which permitted it to be easily distinguishable from contaminants in bactericidal tests. Bactericidal activity is localised in the cellular components of the coelomic fluid, particularly in the red spherule cells (Messer & Wardlaw, 1980) and is demonstrable in almost all animals tested.