The dynamics of clearance, segregation and elimination of a marine bacterium, Moraxella sp., by the shore crab, Carcinus maenas (L.) has been studied utilizing fluorescent and radiolabelling techniques. In addition to the gills, the hepatopancreas was a major site of bacterial accumulation with sequestration occurring within haemocyte clumps and groups of stationary cells in this organ. The heart, excretory organ and subcuticular tissues also incorporated bacteria, but to a lesser extent. By the first day post-injection, many of the segregated micro-organisms had been removed from the organs. This latter process was not due to the exodus of laden haemocytes or of intact cell clumps from the host but seemed to result from lytic action by the host blood cells. Little material arising from such bacterial/haemocytic interaction was, however, immediately excreted, and much was relocated in the general body tissues as well as the gill nephrocytes.

INTRODUCTION

Implicit in some recent models of the dynamics of planktonic systems, for example that of Steele & Frost (1977) is the concept that filter-feeding copepods may be scaled by size when considering feeding in relation to the size composition of their paniculate food. For a particular organism ingestion of phytoplankton has been considered to be a function of its own weight and the size composition of the phytoplankton available to it. Such scaling has been assumed to occur both in an intra- and interspecific sense, with model development involving a ‘large’ copepod {Calanus) able to feed and grow more efficiently on ‘large’ cells (diatoms) and a ‘small’ copepod {Pseudocalanus) better adapted to feed on ‘small’ cells (flagellates). However, although the general relationship between growth and metabolic rate and body size is widely accepted (Banse, 1976; Fenchel, 1974) this relationship between dietary particle-size composition and size of organism has remained a working hypothesis with little experimental support..

Immersed shannies (Blennius pholis) showed peak locomotory activity coincident with daylight high tides. Emersion caused cessation of breathing and bradycardia though Q02 was little affected. Q02 fell, however, when the abdomen was enclosed in an impermeable sheath to block cutaneous respiration. Gulping of air into the extensively vascular oesophagus probably also acts as a means of aerial respiration. Reimmersion of fish caused a transient bradycardia followed by a tachycardia and a fall in Q02 followed subsequently by a rise. The results are discussed in relation to the behavioural, circulatory, respiratory and morphological adaptations of the shanny to the intertidal habitat.

In an earlier study Pingree, Pennycuick & Battin (1975) used a diffusion model to study the monthly temperature distribution and heat exchange in the English Channel. This showed that the diffusion would have to be adjusted according to the tidal ellipses for an improvement in the predicted temperature distributions, and that advection was probably an important factor at certain times of year. An attempt to use the same model for prediction of the salinity distributions was unsuccessful due partly to lack of information on run-off, precipitation and evaporation. The present study is an attempt to provide an overall monthly mean heat and salt budget for the eastern English Channel and Southern Bight of the North Sea which could serve as a preliminary to a two-dimensional mixing/advection model in which the horizontal eddy diffusion is represented as a tensor based on the tidal ellipse properties (Hunter, 1975).

A cytochrome P-450-dependent benzo[a]pyrene mono-oxygenase enzyme system (BPM) has been identified and partially characterized in males of the shore crab Carcinus maenas (L.). Apparent Km values obtained at 30 °C using microsomal preparations from the antennary glands of animals collected during summer were in the range 1.61–2.11 µM. The cytochrome P-450 content was 0·022 nmol/mg microsomal protein when BPM activity in the same preparation was 0·085 nmol/mg protein/min.

INTRODUCTION

Lincoln (1979) stated that ‘four species (of Gammaropsis Liljeborg) are reported from the British Isles, Gammaropsis maculata (Johnston), G. palmata (Stebbing & Robertson), G. nitida (Stimpson) and G. sophiae (Boeck)’. In fact, six species of Gammaropsis have been reported from the British Isles in the literature, the records of G. lobatus (Chevreux) (Spooner, i960) and G. melanops (Sars) (Jones, 1948) having apparently been overlooked by Lincoln (1979). Spooner's (1960) material is apparently no longer extant, but the material attributed to G. melanops by Jones (1948) has been re-examined by us and found to be referable to G. lobata. Recent collections of G. lobata from the west coast of Ireland confirm a rather wide distribution of this species in the southwest of these islands.

Five species of Gammaropsis are therefore now known from these islands, and G. melanops can, at least for the present, be deleted from the British and Irish list of species.

Lincoln (1979) was unable to examine any British material of G. sophiae, everything labelled as such, in the material examined by him (including the Norman collection at the B.M.N.H.)* being referable to G. nitida. He therefore figured the species from West African material. G. sophiae is quite widespread along the southwest coast of Ireland and since it differs somewhat from the material described by Lincoln (1979) it is figured herein from the Celtic Sea.

Krapp-Schickel & Myers (1979) reviewed the Mediterranean species of Gammaropsis and segregated the species into two groups, group ‘A’ species characterized by the possession of a toothed urosome, toothed coxa 1 and long acute epistome, and group ‘B ‘ species characterized by having a smooth urosome, smooth coxa 1 and short epistome.

A simple aquarium system was used to keep large ormers collected from the wild and to rear juveniles from fertilization up to age one year. Spawning was induced by exposure to u.v. irradiated sea water and counts made of gamete production. Repeated spawning was observed in males and from egg counts it was inferred that females also undergo repeat spawning in the wild.

Juvenile ormers were reared on simple collectors up to 4 mm shell length and later in open mesh cages. There was large variation in growth rate between individuals among the juvenile ormers. After one year shell lengths varied in the range 6·2–21·o mm.

Twenty-three adult ormers (shell length 40·4–93·6 mm) were reared for eight months in a tank with a concrete shelter. The smaller ormers remained under the shelter much more than the larger ones, some of which adopted a permanent position outside the shelter. In the study period growth was greater in the smaller specimens (less than 70 mm shell length) than in the larger ones.

A numerical model is used to derive the diurnal tides on the N.W. European Shelf. The quadratic friction term was linearized using both tidal and wind driven currents. The semidiurnal tidal currents essentially provide the friction for the diurnal tides except in a few relatively small regions (semidiurnal current amphidromes) and the Skagerrak where the wind driven currents dominate. Accurate M2 tidal currents are required for the diurnal bottom stress tensor and the M2 tidal current amplitudes are considered accurate to about 95%. Some discrepancies between model energy M2 dissipation rates and some observed estimates reported for the English Channel and Celtic Sea regions were noted.

INTRODUCTION

Members of the leucosiid genus Ebalia are typical oxystomatous crabs which live on subtidal coarse sediments at depths ranging from a few metres to over 2500 m. Although this genus has an almost worldwide distribution, no studies of the population biology of any species has been made.

Five species of Ebalia occur round British coasts (Ingle, 1980), four of which have also been recorded from the Clyde Sea area (Allen, 1967). During dredging surveys in this region, a sizeable population of Ebalia tuberosa (Pennant) was located in the vicinity of the University Marine Biological Station on Great Cumbrae Island, and regular sampling of this population over a period of two years provided the data on which this study is based.

Apart from a few references to the occurrence of female crabs in berry (Lebour, 1928a, b; Marine Biological Association, 1957; Allen, 1967) and to the occurrence of larvae in the plankton (Jorgensen, 1923, 1925; Lebour, 19286; 1947; Rees, 1952; Williamson, 1956; Marine Biological Association, 1957; Bruce, Colman & Jones, 1963; Crothers, 1966), no other information on the population biology of E. tuberosa is available.

Laboratory experiments to determine the stage durations of Pseudocalanus elongatus (Boeck) and Calanus sp. have been described. The duration of all the nauplius and copepodid stages at temperatures ranging from 4° to 15 CC is given for both species. The effect of temperature on the development rate of copepod eggs has also been determined at these temperatures. The effects of food supply and temperature on the distribution, abundance and development rate of different species of copepods are discussed.

Spawning and post-gastrula development of planula larvae of the ahermatype Caryophyllia smithi are described. Gametes develop within the mesenteries of the adults usually between January and March, are discharged through the mouth of the polyp and fertilized externally in the sea water. Ova are either brown or cream in colour, spherical or slightly oval in shape and are 130–150 µm in diameter. Planulae are fully formed after 48 h, when feeding commences. A large apical tuft (30–60 µm in length) is present but only during the first six weeks of pelagic life. After 8–10 weeks of feeding in culture larvae reach a length of 800–1000 µm: they are then fully developed and ready to settle. Attention is paid to the effects of sea water temperatures on reproduction; locomotion and feeding behaviour of planulae are also discussed.

Biological precipitation of barite (barium sulphate) is highly unusual (Bowen, 1966, p. 129). This mineral forms statoliths in certain ciliates (Hubert et al. 1975), but the only animals in which it is known to occur in significant quantities are xenophyophores, a group of giant deep-sea protozoans placed in a separate class within the Rhizopoda (Levine et al. 1980). The importance of these previously obscure organisms at abyssal, and bathyal depths in the oceans has lately become increasingly appreciated, mainly through the work of Tendal (1972, 1973, 1975a, b, 1980a, b; Tendal & Lewis, 1978).

Measurements of pH, oxygen content, O2-combining capacity, and haemoglobin concentration were made for the vascular blood of the burrowing polychaete Neoamphitrite figulus in order to assess the role of its two respiratory pigments in respiration. The oxygen equilibrium curve of the erythrocruorin (extracellular haemoglobin) in the vessels was sigmoidal, having an n50 value of 1·5 and a low affinity for oxygen as determined by the P50 which was 26 mmHg at pH 7·31 and 18 °C. O2-binding by the erythrocruorin is sensitive to changes in pH (Δ log P50/Δ log pH = –0·24 to –0·29). The coelomic cell haemoglobin has a hyperbolic equilibrium curve (n50 = 1·0) and a high affinity for oxygen (P50 = 4·5 mmHg) independent of pH, suggesting an oxygen transfer system from the erythrocruorin to the coelomic cells.

The effects of experimentally manipulated barnacle cover on the population size, mortality and growth of Patela vulgata L. were investigated on a vertical, barnaclecovered pier at Port Erin in the Isle of Man. One area was left untouched as a control, half of the barnacles on a second were scraped off in a chequered pattern, and on the third the barnacle cover was reduced to less than 2 °0. Subsequent growth rates were inversely proportional to barnacle cover. Mortality was highest on the control. Recruitment of limpets was markedly enhanced by the mosaic of 50 % barnacle cover.

Behaviour on this vertical face differed from that on nearby more gently sloping shores, with foraging during emersion being more prevalent: however, barnacle removal reduced this foraging when the tide was out. The foraging of Patella vulgata whilst emersed was similarly shown to be more prevalent on vertical than horizontal surfaces at other localities in Britain. Emersed foraging on the pier was dependent on high humidity. It is suggested that on vertical surfaces, particularly if barnacle-covered, P. vulgata are more dependent on foraging whilst emersed because of the greater risk of dislodgement by waves when feeding whilst the tide is in.

INTRODUCTION

Until recently saturated sterols – stands – were not thought to play an active biochemical or physiological role in organisms. They were generally considered to be diagenetic products of the microbiological reduction of the common natural product Δ5sterols and as such have been reported in sediments (e.g. Gaskell & Eglinton, 1975).

Prior to the regular use of capillary gas liquid chromatographic (GLC) and gas chromatographic-mass spectrometric (GC-MS) techniques the majority of sterol analyses had been performed on packed column GLC. It is now well known that in the analysis of some of the complex mixtures of sterols which commonly occur in the marine environment, the use of packed column GLC techniques alone is an inadequate procedure (e.g. Ballantine; Roberts & Morris, 1976; Ballantine et al. 1977). Certainly complete resolution of the sterol-stanol pairs cannot normally be achieved on packed columns and identification of the components within each peak has to be made by multiple mass spectral scans across each peak (Ballantine et al. 1976). With the advent of techniques with better resolving powers, significant amounts of natural product stands have been found in a wide spectrum of phyla including molluscs, sponges coelenterates, echinoderms, annelids and tunicates (Morris & Culkin, 1977 and references therein; Ballantine et al. 1976; Ballantine, Lavis & Morris, 1979, 1981; Voogt, 1976; Ballantine et al. 1977; Ballantine et al. 1978; Gupta et al. 1979). In some instances the stanols have been found to account for over 50% of the animals component sterols.

As the sterol profile of marine invertebrates becomes better understood it is clear that stanols are important biochemical constituents of many of these organisms; but little is known of their significance in any biochemical or physiological role.

As long ago as 1911, Henze first showed that the ascidian, Phallusia mammillata has the ability to accumulate vanadium from the surrounding sea water into its tissues. Since this report, many other workers have demonstrated vanadium as well as other metals such as iron (Koval'kii, Rezaeva & Kol'tsov, 1962; Milanesi & Burighel, 1978; Macara, McLeod & Kustin, 1979a), manganese (Noddack & Noddack, 1939) and niobium (Carlisle, 1958) in various tunicate species.

The responses of marine animals to changes in hydrostatic pressure have been widely studied (see reviews by Knight-Jones & Morgan, 1966; Fliigel, 1972; Nay lor & Atkinson, 1972). Most of these studies, however, have been concerned with invertebrates, particularly Crustacea, and few deal with fish (Gordon, 1970). Blaxter's (1978) review of baroreception summarizes recent work in this field and points out that a limitation of many experiments has been the use of sudden, rather than gradual, pressure changes. The limitation is especially true with respect to fish. This paper describes the results of experiments in which young plaice (Pleuronectes platessa L.) were subjected to hydrostatic pressure cycles of varying amplitude and frequency in order to describe the response to such pressure cycles, to determine the threshold of the response and to relate the response to the fish's behaviour in the sea.

Fertilizations of Magelona filiformis, M. alleni, and M. mirabilis were made in the laboratory and the resulting larvae reared through the earliest stages. Later stages of all three species were obtained from the plankton and induced to metamorphose in the laboratory. The long larval tentacles derive from the prototroch and associated tissues. Adult tentacles appear during later pelagic life as thickenings at the bases of the larval tentacles; the latter, together with the long provisional bristles, are discarded at metamorphosis. The early larvae of M. alleni are considerably larger than equivalent stages of the other two species. The early larvae of M. mirabilis are peculiar in that at first the larval tentacle of the left side is a mere stump while that of the right side is relatively large; in the other two species both tentacles are of equal length. Larvae of the three species are readily identifiable by characters described in the text.

Examination of the reproductive biology of three closely related sympatric astropectinid asteroidshas revealed two distinct reproductive strategies. In Plutonaster bifrons and Dytaster insignis the gonads are serially arranged and open at gonopores located at the tip of genital papillae found on the dorsal arm surface between the bases of the paxillae. The ovaries of these species produce numerous small (ca. 120/«n diameter) eggs which in Plutonaster bifrons appear to show a distinct synchrony of production. Initiation of gametogenesis occurs in June to August of each year with oocyte growthcontinuing until March with a spawn-out in the period March to early June. In specimens where spawningdoesnot occur, there would appear to be internal oocyte degeneration, or after spawning relict oocytesundergo phagocytosis. In males initiation of spermatogenesis may occur in August/September of eachyear but after this synchrony of sperm development is not evident. In Psilaster andromeda gonads are located at the base of the arms and each gonad opens at a single gonopore. A number of small (<300 /«n) oocytes are produced by each gonad. Some of these are phagocytosed and some undergo vitellogenesis and grow to a maximum size of 950 fim before being spawned. Unspent oocytes undergo internal degeneration. In neither females nor males is there any evidence of reproductive synchrony. From these egg sizes, fecundities and gametogenic strategies, we infer indirect planktotrophic development for Plutonaster bifrons, the transfer of a seasonal surface production to deep water providing a food source for developing larvae. The egg size and or close to the sea-bed, as there is no evidence of brooding in this species.

INTRODUCTION

Both the inner and outer epithelia of salps propagate action potentials (Mackie & Bone, 1977). Skin pulses in the outer epithelium underlying the test (OSPs) evoked by mechanical or electrical stimulation of the epithelium ‘enter’ the brain and may alter the regular rhythmic locomotor activity (Mackie & Bone, 1977; Anderson et al. 1979). The route of'entry’ has not been determined, but has been assumed to be via the axons of the scattered mechanoreceptor sensory cells lying in the outer epithelium. The OSP system would thus operate to extend the sensory field of such cells, as in the appendicularian Oikopleura (Bone & Mackie, 1975; Bone & Ryan, 1979) where two sensory cells are coupled to a conducting epithelium.

Salps alternate generations between the solitary asexual oozooid, and the aggregated sexual blastozooids (budded from the stolon of the oozooid). The linked blastozooids form chains, along which OSPs pass to regulate the locomotor behaviour of individual zooids in the chain. The zooids are not linked by gap junctions, and OSPs pass along the chain in a complex.manner, involving alternating epithelioneural and neuroepithelial synapses (Bone, Anderson & Pulsford, 1980; Anderson & Bone, 1980). The OSP system of the oozooid generation is less well understood, although it is known that OSPs in the outer epithelium of the oozooid propagate into the stolon, where they have been studied by Anderson (1979). This paper shows that oozooids possess a similar system of neuroepithelial synapses to that of blastozooids, and that these ‘ drive’ OSPs in the same way as occurs during the regenerative transmission of OSPs along the blastozooid chain.