Concentrations of lead in the soft tissues of the deposit-feeding bivalve Scrobicularia plana have been compared with the physicochemical characteristics of sediments in 20 estuaries in southern and western England and one in north-west France. The results indicate that the biological availability of lead in the sediment is controlled mainly by the concentration of iron, and that the concentration of lead in the bivalve may be predicted from the Pb/Fe ratio in 1 N hydrochloric acid extracts of surface sediments.

Patella vulgata possesses nine different pedal glands, six of which pour their secretions on to the sole. Proteins secreted by the marginal gland into the marginal groove are used for locomotion, especially when the limpet moves off following a period of adhesion. Another protein-secreting subepithelial gland, sparsely present throughout the foot, is also believed to be used in locomotion. A third gland type is present in the epithelium of the sole. The secretion of these epithelial mucocytes which is a weakly acidic muco-polysaccharide (MPS) is likely to have a locomotory function. Three other sole glands secrete highly viscous acidic MPS. Their secretions are likely to have an adhesive function. The three other glands present in the foot are contained within the side-wall. Of these, two are believed to secrete mucus to protect the animal against desiccation during emersion; and the other, present only in young P. vulgata, pours its acidic MPS secretion into the epipodial streak. This secretion consolidates debris before it is cleared from the pallial cavity; in adult animals, muscular contractions of the foot are powerful enough to clear debris without the help of the epipodial gland.

In Acmaea tessulata the six glands present open out on to the sole and correspond in position, composition and function to the six glands of the sole of P. vulgata. There are no glands within the side-wall.

The gills of Patella consist of a row of triangular shaped leaflets suspended from the roof of the pallial groove. The surface of each gill is thrown into a series of transverse furrows. Tufts of cilia are irregularly distributed over the surface and generate a current of water which flows in the opposite direction to the flow of blood within. The central part of the gill comprises a large haemocoelic space traversed by trabeculae which contain muscle fibres and suggesting that the flow of blood through the gill may be under nervous control. A blood channel runs around the periphery of the gill.

The epithelial layer bounding the blood space comprises a single layer of columnar epithelial cells. The outer surface is protected by a structured mucopolysaccharide glycocalyx held in place by a dense mat of microvilli. The cells contain clearly defined mitochondria, Golgi complex, lysosomes, rough and smooth endoplasmic reticulum. In addition, the non-ciliated cells are characterized by a layer of membrane-bound granules, of unknown function, in the apical cytoplasm.

Phagocytes are frequently found associated with the basement membrane. They contain large membrane-bound granules and appear to move outwards between the epithelial cells to expel the granules at the outer surface of the gill. It is possible that the gill has an excretory as well as respiratory role in the physiology of the animal.

Mussels (Mytilus edulis L.) were held under five different experimental conditions for 8 weeks during which measurements of physiological condition, and certain cytological and cytochemical observations, were made. The mussels were then induced to spawn and the numbers of eggs released, the weights of these eggs, and their biochemical composition, were determined. During the experiment new gametes were developed by mussels under all conditions, but there was also a simultaneous regression and resorption of previously formed gametes, particularly in mussels under the greatest stress from high temperature and lack of food. The degree of stress experienced by the animals was measured as the scope for growth, or the energy available for somatic growth and the production of gametes. The distribution and activity of lysosomal enzymes within the Leydig tissue of the mantle suggested that autolysis of these cells occurred, coupled to the mobilization of glycogen for gametogenesis. Mussels under stress produced fewer and smaller eggs, in smaller follicles, than mussels not under stress. The biochemical composition of the eggs (as µg of biochemical component per mg of egg) did not vary consistently with adult condition, but eggs from stressed females had less lipid and protein than eggs from normal females. It is suggested that these relationships between the physiological condition of the adult, gametogenesis, fecundity and the biochemical content of the eggs are important for understanding the impact of the environment on ecological fitness.

An acute toxicity threshold of 0·09–0·10 ppm added copper was determined for specimens of Mytilus edulis from the Menai Strait which were exposed to copper (as CuSO4) in a flowing sea-water system.

Results are presented which show that the closure response of the mussel to added copper is a three-part process. First, a sharp adduction of the shell valves is seen at a mean total copper concentration of only 0·021 ppm, then as the copper concentration rises, ‘testing’ behaviour is observed and finally the shell valves close to isolate the animal from its environment. The complete valve closure mechanism only operates at added copper concentrations of 0·2 ppm or more. The initial behavioural reaction of valve adduction at low concentration occurred at a significantly higher mean total copper concentration (0·16 ppm) in mussels which had been previously acclimated to 0·02 ppm total copper in sea water for 10 days.

Ontogenesis of the eyestalk structures in Palaemon serratus has been studied during the larval and postlarval life by means of scanning electron microscopy (SEM) and light microscopy (LM). At hatching, a larval sensory pore is observed in the zoea. The organ of Bellonci is present with its typical onion bodies. During larval life, this organ grows and differentiates. Vacuolization in the organ of Bellonci starts in stage 4. At the same time, the giant neuron appears, but the sinus gland cannot be recognized before stage 5.

During larval life, vesicular cells are present in the optic medullae with an increase during stages 4 and 5. The differentiation of the neurosecretory cells of MEX (medulla externa X-organ) and MTGX (medulla terminalis ganglionaris X-organ) occurs with metamorphosis. The main sensory pore appears with metamorphosis and becomes clearly visible in postlarval life.

The movements of the structures, which occupy different positions in larvae and adults, are described in relation to the longitudinal axis of the eyestalk. A schematic representation explains the torsion of the eyestalk and the dynamics and growth during the formation of the eyestalk structures.

Specimens of Pagurus bernhardus (with and without shells) were exposed to both gradual (sinusoidal) and abrupt (square-wave) salinity fluctuations and changes in haemolymph osmolality, tissue water content and oxygen consumption monitored. Oxygen consumption was also monitored under steady-state conditions; under these conditions there was no significant difference between the rate of oxygen consumption by animals with shells and animals without shells. Oxygen consumption was found to vary with body weight according to the equation O2 consumption = 0·292 W0·668. During exposure to fluctuating salinities the crabs with shells were seen to increase loco-motory activity when the external medium declined to approximately 75% sea water. Haemolymph osmolality values followed the same pattern of change as the external medium; the haemolymph of crabs without shells became significantly more dilute during exposure to low salinity than did that of crabs with shells. P. bernhardus showed significant increases and decreases in hydration level as salinities fell and rose respectively. Crabs with shells showed a marked temporary increase in oxygen consumption when the external medium declined to approximately 75% sea water; crabs without shells showed no such response. The importance of the shell as a means of protection against dilute media is discussed.

The ecology and feeding behaviour of Antedon bifida bifida (Pennant) were studied in situ at five sites on the east and west coasts of Ireland. These encompassed a range of different habitats and hydrographic conditions, including currents of varying intensity, oscillations due to wave action, and multidirectional water movements.

Unlike other comatulids hitherto studied, this species was found to be relatively unspecialized in its choice of habitat and to display great flexibility of movement in its arms and pinnules which enable it to adapt to and feed in each of the different types of water movements described. Neither diurnal nor tidal feeding rhythms were observed, the animals being found to feed almost continuously. The relatively unspecialized nature of this species is discussed in relation to the almost cosmopolitan distribution of the genus Antedon.

Of nine northern European species of the Gadidae examined in the aquarium, or in cages in the sea, four produced sounds. The vocal species were the haddock, Melanogrammus aeglefinus (L.); the cod, Gadus morhua L.; the lythe, Pollachius pollachius (L.); and the tadpole-fish, Raniceps raninns (L.). The main differences between the calls of the vocal species lay in their temporal structure, all the calls being divisible into brief pulses of low frequency sound, repeated at different rates and in different groupings. Calls with this structure yielded spectra with a series of spaced harmonics, the frequency spacing depending upon the pulse repetition rate.

Sixteen additional species were dissected, and seven of these showed well developed muscles attached to the swimbladder, similar to those found in the four vocal species. The remaining nine species, together with the five non-vocal species examined in the aquarium, lacked the muscles.

The behavioural significance of the calls and the operation of the sound producing mechanism are discussed.

The compositions of the lipids of egg yolk, blood plasma and liver of Scyliorhinus canicula from the Irish Sea were examined by column chromatography and by various other methods. Considerable differences in composition were found between these three tissues. Phospholipid and triacylglycerols were the major components of lipids of yolk and liver respectively. Cholesterol, free fatty acid and phospholipid were present in all three tissues. Squalene and alkyldiacylglycerols were present only in traces, if at all. In this paucity or absence of squalene, this population differs from Mediterranean S. canicula. The compositions of the lipids of the livers of six shark species (Scyliorhinus canicula, Scyliorhinus stellaris, Squatina squatina, Galeorhinus galeus, Mustelus asterias and Squalus acanthias) were compared by thin-layer chromatography. In all cases, triacylglycerols were the major components, while hydrocarbons were not detected by this method in any of the species. Alkyldiacylglycerols were present as a major component only in Squalus. Qualitatively, the other five species showed only minor differences from each other; these five species are largely confined to shallow coastal waters. The results follow previous work in showing that low-density lipids, such as squalene and alkyldiacylglycerols, are major components of hepatic lipid in shark species from deeper waters, although not necessarily from great depths. An attempt is made to explain the prevalence of such lipids in pelagic sharks in evolutionary terms. It is suggested that they may serve as an analogue of the swimbladder of teleosts.

Phytoplankton from Loch Creran, Argyll was maintained in continuous culture for 41 days. During most of this time the mixture of species retained the diversity and dominance pattern typical of summer phytoplankton in the loch, notwithstanding the manipulation of algal nutrient status to bring about phosphorus control of growth. Results suggest that most detritus was washed out early in the experiment.

The aim of the experiment was to test the applicability to natural multispecies phytoplankton of part of Droop's (1974, 1975) model of nutrient-limited algal growth. ‘Quasi-steady states’ with respect to concentration of chlorophyll, particulate carbon (PC), particulate phosphorus (PP) and particulate nitrogen (PN), wereobserved at two levels of input of dissolved inorganic phosphorus. At other times the algal phosphorus quota (estimated from the ratio of PP to PC) varied from about 0·002 to 0·015 atoms P per atom C. Specific growth rate was estimated from the rate of increase of PC. During part of the experiment, growth rate was linearly related to reciprocal phosphorus quota, thus confirming the applicability of the model.

Over a period of 10 years, 1964–74, primary production has been measured at three stations across the western English Channel using the 14C method. Results for carbon fixation, cell counts and mean seasonal production are illustrated. Statistical analyses show that, at two of the three stations, carbon fixation in 1966 was significantly greater than expected and that annual production differs significantly at each of the stations. The variations observed are discussed in relation to other changes recorded in the area during the same period. A deck incubator used for simulated in situ14C experiments is illustrated.

An examination of infra-red satellite images of the North-West European continental shelf suggests that cross-frontal mixing takes the form of cyclonic eddies. These are about 20–40 kmin scale and persist for a few days. It is suggested that the dynamics of cyclonic eddies willbe important in the development of frontal phytoplankton blooms.

An estimate is made of the mean value of residual flow through the Dover Strait for each month over the 24–year period from 1949 to 1972. The estimates are based on results from a modelling investigation by Prandle (1978) where it was shown that the residual flow consists of three components, (a) a tidal residual, (b), a wind-driven residual and (c) a flow due to a long-term gradient in mean sea level. The components (a) and (c) are assumed to be constant and the value of (b) is deduced using wind data recorded by Dutch Light Vessels located in the southern North Sea.

The mean flow over the whole period amounts to 155 × 103 m3 s–1 into the North Sea with a maximum value of 364 x 103 m3 s–1 and a minimum of – 15 × 103 m3 s–1 (out of the North Sea). One notable feature of the complete time series is the surprisingly small variation in the annual mean flows; perhaps this stability in the annual flow is of significance to the marine biology of the area.

The validity of the computed time series is established by reference to comparable data including a 9–year record, from cross-channel submarine cables, of the potential induced by the flow of water through the Earth's magnetic field. Additional comparisons are also made with the results of a previous study of daily-mean flows.

A rocky shore exposure scale, intended primarily for use in the Fensfjord area, Western Norway, has been prepared. This scale is developed from an earlier scale devised by Ballantine for Milford Haven, Wales, making use of species abundance curves along the wave exposure gradient. Independent evidence for the validity of the scale is provided by shell shape variation in Nucella lapillus and by the height of the black lichen zone in the supralittoral fringe. The successive steps in the preparation of the scale are outlined, definitions of the exposure grades are given in tabular form for the restricted set of species analysed numerically and descriptions are provided in an extended form to provide a fuller picture for users of the scale. It is believed that the scale will prove applicable to other rocky shores around the North Sea.