The effect of copper upon carbon fixation in coastal phytoplankton assemblages has been studied in relation to both the metal concentration in the water and the levels taken up by the plant cells. The phytoplankton populations were those present in water samples collected from Station L4 in the English Channel in the late autumn of 1979. The lowest copper concentrations causing detectable inhibition of photosynthesis lay in the range 1–25 μg/1, well below the levels which have been reported to be present in some sea areas around the British Isles; metal pollution may thus be influencing primary production in these contaminated regions.

Data on the distribution of dinoflagellates in the surface waters around the British Isles in July 1977 were analysed by correspondence analysis. Four communities of dinoflagellates were recognized, and the occurrence of each was related to various environmental parameters. The vertical stability of the water column is considered to be the most important factor in determining the relative abundance of individual species.

Arsenic concentrations in estuarine sediments from England and Wales range over three orders of magnitude. The highest concentrations, up to 2500 μg/g, occur in the sediments of estuaries in south west England associated with past or present metalliferous mining activity. Strong correlations exist between arsenic and iron in 1 N-HC1 extracts of different estuarine sediments. The As/Fe ratio in those estuaries not contaminated with mine wastes is 11 × 10−4, increasing to 190 × 10—4 in metalliferous sediments.

Mucus, leaving the pyloric duct in a continuous flow, is conveyed over the epithelium of the aboral part of the pyloric stomach. There nutrients are resorbed and concentrated into the haemal system, which is in close contact with this part of the stomach. It is supposed that this material consists of nutrients in complex form especially destined for the use of gonad development.

Aspects of the digestive cycle of Carcinus maenas have been studied by transmission and scanning electron microscopy, X-ray microanalysis and light microscopy. Movements of ingested material have been followed by feeding the crabs with Mytilus edulis (L.) labelled with colloidal particles of gold or thorium oxide.

Actinocoryne contractilis is a new marine, benthic and stalked member of the Centrohelidia (Heliozoa) whose biology, motile behaviour and cytology are described. Preliminary results concerning the life cycle are given. The stalked form emits small subspherical planktonic heliozoans which settle and give rise to the stalked stage again.

A key to all nine described marine species of naked lobose amoebae classified in the genus Vannella Bovee, 1965, is presented. All six species studied with the electron microscope have the characteristic surface structure found also in freshwater members of the genus. The key includes five species isolated from British waters, including three new species; a fourth new species is from the Persian Gulf area. Generic identification of Vannella, even in mixed material, can be made readily with the electron microscope, which is sometimes necessary for positive distinction from Platyamoeba. Further identification to species is a light-microscopical procedure. Members of this genus are cultured on bacteria, which are probably their main food in nature.

The functional morphology of the coelomocytes of larval oysters, Crassostrea virginica and C. gigas, based on observations of live animals and histological and ultrastructural examination of tissues, is presented. Two predominant types of coelomocytes were found in the larval oysters. One, the SER cell, not found in the adult oyster, is large with a spheroidal nucleus, and exhibits basophilic cytoplasm which consists of abundant smooth endoplastic reticulum. This cell appears to participate in metabolic conversion processes. The other predominant cell type, the phagocyte, appears identical to the phagocyte observed in the adult oyster. Both differential cell types were observed from one day post fertilization to metamorphosis, the oldest stage studied.

Overall incidence of metacercariae of Maritrema arenaria differed substantially at each of the three sites investigated. In each case, however, numbers were higher than those previously observed in the British Isles. Results indicate that gulls rather than waders are the more important final hosts of this parasite in the areas investigated. At one site where a more detailed survey was carried out metacercariae were more abundant on the upper half of the shore and they displayed a marked preference for barnacles on living Littorina littorea shells as compared to barnacles on rocks. Evidence would suggest that the two most likely molluscan hosts of this trematode are Littorina saxatilis and Nucella lapillus.

Two types of artificial substrate (nylon pan-scourers) have been shown to be highly efficient collectors of cryptofauna on rocky shores. The communities which develop in them are closely similar to those which develop in naturally occurring red algal turfs in Bantry Bay. The physical structure of the red algae appears to be the prime factor in determining the development of populations of most of the cryptofaunal species studied. In monitoring protocols artificial substrates of the types described here can be substituted for naturally occurring red algae in studies on shore cryptofauna obviating the necessity for destructive sampling of algae and facilitating statistical analysis by providing a standard ‘unit’ of substrate for comparative purposes. Furthermore, recruitment intensity of two species of gastropod has been shown to be similar in the artificial substrates to that in natural turfs

It has previously been shown in Cerastoderma edule that during periods of active growth the increments between successive growth bands each correspond to a period of tidal immersion. They can therefore be used to record instantaneous growth rates. For shells which, like Cerastoderma, conform to the Bertalanffy equation, such increments can be used independently of age and size to measure the Bertalanffy constant over brief intervals.

The intertidal bivalve, Cerastoderma edule, when grown under constant conditions of temperature, salinity, water flow, light and food supply lays down faint internal shell bands at approximately semi-diurnal intervals, though with wide variations in periodicity from individual to individual. Animals grown continuously immersed under natural light/ dark cycles on a raft or below the tide marks produce similar bands. These bands are very faint compared with those in the shells of animals grown intertidally or under simulated semi-diurnal tidal conditions of emersion and immersion. The bands of intertidal animals also differ in their almost exact coincidence with the number of emersions. Cockles subjected to a diurnal cycle of immersion lay down strong bands coinciding approximately with the number of daily emersions, together with irregular faint bands. Thus the total number of bands exceeds the number of emersions.

Siboglinum ekmani can accumulate labelled alanine, glycine, phenylalanine, glutamic acid, galactose, glucose, mannose, acetic acid, palmitic acid, lactic acid and glycollic acid from sea water at concentrations between 1 and 100 μM/1. Uptake of fructose and mannitol was not detected. The neutral amino acids were absorbed against a concentration gradient, probably by a carrier-mediated transport mechanism, and similar mechanisms may exist for acidic amino acids and glucose. Most of the compounds entered into the metabolism, but 90% of the glycine accumulated was retained as free amino acid. The presence of glucose appeared to depress uptake of alanine, but uptake of glucose was stimulated by alanine.

A seasonal cycle in byssal attachment strength of Mytilus edulis is described in a population of mussels on the South Wales coast. Attachment strength reaches a maximum in September with a minimum in May.

INTRODUCTION

Many seasonal cycles of a physiological nature have been described in the common mussel Mytilus edulis L. (reviewed by Gabbott, 1976; also Pieters et al. 1978; Zurburg et al. 1978), some of which, for example the annual accumulation and subsequent utilization of energy substrates, appear to be linked to gametogenesis. Following spawning in the spring the gonads of Mytilus enter a resting phase; metabolic demands are low. Glycogen and protein are accumulated in the tissues at this time as phytoplankton is abundant. Gonadal development commences in autumn when phytoplankton density has declined and energy is supplied by the utilization of stored reserves. Pieters et al. (1978) have suggested that the resulting decline in reserves is accentuated by the need for greater byssus production at this time to secure the mussels against the rigours of autumn and winter storms. No accounts exist of field studies which might support this hypothesis.

Evidence is given which suggests that harbour seals use some form of echolocation. When visual cues are reduced, these seals make click vocalizations similar to those of animals which are known to echolocate. They are able to find live fish in total darkness, producing clicks while doing so.

The oxygen consumption of the intertidal teleost Blennius pholis L. has been investigated during and subsequent to quinaldine anaesthesia, using a continuous flow apparatus. Marked reductions in oxygen consumption were noted in high concentrations of quinaldine (10 and 20 ppm), and both entry into anaesthesia and recovery from it were rapid. A period of enhanced oxygen consumption followed anaesthesia, except in the lowest concentration of quinaldine (1 ppm). Experiments conducted over a 4 h period with three different salinities (100%, 30% and 10 % sea water) indicated that, under the influence of 10 and 20 ppm quinaldine solutions, the fish more resembled an osmoconformer than an osmoregulator. During anaesthesia, water was lost osmotically in 100% sea water, and gained in the more dilute salinities, although it was possible that some osmotic regulation continued. Physiological measurements indicated that quinaldine is suitable for the capture and marking of fish; for surgical procedures it should be mixed with another anaesthetic, for example MS-222, due to the retention of a response to vibratory stimuli.

The stomach contents of Lepidion eques trawled at depths ranging from 500 to 1250 m on the Hebridean Terrace (56°-57° N, 9°-11° W) are analysed relative to size of fish, depth of habitat and season of the year. Of the 1281 fish examined, 47% had everted stomachs, 29% empty stomachs, 2% had food that was totally unrecognizable while 21% had food whose constituents could be identified. The principal dietary components are the epibenthic and hyperbenthic decapod crustaceans, although a wide variety of other organisms also occur as minor components. Benthic infauna and sessile epifauna are absent from the diet. L. eques therefore feed predominantly on organisms swimming immediately above the sea-bed or actively moving over it.

Young estuarine bass of the 1976 and 1977 year classes were examined for gill parasites between February 1978 and June 1979. 344 specimens of the copepod Lernanthropus kroyeri were recovered from 177 of 289 fish. The distribution of the copepods on the gills showed clear preferences for site of attachment. With 48 such sites delineated per fish, 143 of 183 female copepods favoured a single site – the internal face of the medial sector of the posterior hemibranch of the second gill arch. 57 of 161 male copepods chose attachment to the external face of the medial sector of the anterior hemibranch of the second gill arch. Only seven copepods in all were found attached at any of the twelve possible sites on the first gill arch, and none at all at the six possible sites on the posterior hemibranch of the fourth gill arch. Explanations for the observed distribution are discussed in terms of the strength of the branchial ventilation currents over the different gills coupled with observations on the special respiratory adaptations of these parasites.

From analyses of the gut content of Sabella penicillus L. Hunt (1925, as S. pavonina) showed that the food consists mainly of finely sorted plankton and detritus. The chief constituents were usually bottom-living diatoms, but planktonic forms when present made up the bulk of the food. Peridinians, silicoflagellates, foraminifera and tintinnids were also found to occur. These observations were confirmed by Nicol (1930) and in the present study, in which some individual worms were found to contain very large numbers of planktonic dinoflagellates, and pieces of red, green and brown algae, and encysted flagellates.

Dinoflagellate blooms, chiefly of Gyrodiniwn aureolum Hulburt, occurred along the south and south-west coasts of Ireland in August and September 1978 and mortalities of shore animals and of rainbow trout Salmo gairdneri held in sea cages were described from Dunmanus Bay (Parker, 1980). Since May 1978 four rocky shore sites in Bantry Bay and one in Dunmanus Bay have been monitored monthly (Myers, Cross & Southgate, 1978, 1979). At each site a permanently marked transect is monitored, limpet shell lengths are measured in marked quadrats at M.H.W.N., M.T.L. and M.L.W.N. and settlement, growth and mortality of barnacle species are studied on vertical rock faces. Discoloration of the water was observed at all five monitoring sites in August 1978 but no effects on the littoral or sub-littoral fauna and flora were detected (Cross & Southgate, 1980).

In 1979 a reddish-brown discoloration of the water in Bantry and Dunmanus Bays was first observed in early September. Surface water samples taken at the regular sampling sites between 5 and 10 September revealed very high densities of Gyrodinium aureolum. Slight discoloration of the water persisted at Eagle Point until October and at Glengariff Castle until early November. During this period mortalities of shore fauna were observed at four of the regular sampling sites. Highest mortalities were observed at Pointabulloge in Dunmanus Bay. When visited on 8 September many Patella spp. on the transect were either dead or, if alive, could easily be removed. An estimated 75% of Gibbula umbilicalis were lying inverted in rock crevices with partially opened opercula which they could close only slowly.