Enzyme and colour phenotypes were determined within a single mid-shore aggregation (n = 106) of the anemone, Actinia equina L. on the east coast of Britain. On the basis of allelic variation at four enzyme loci, a large number (n ≃ 30) of genotypes were distinguished of which only three consisted often or more anemones. Little evidence was found of obvious genotypic clustering, a result which was unexpected since this species broods young which are genetically identical with their parents, and which are potentially available for local (within site) colonization. We propose that the unexpectedly high level of genetic variability encountered at this site, can be explained by the following factors: (1) site and anemone longevities are probably measurable in tens of years, (2) distances travelled by anemones during their lifetime may be considerable, thus resulting in extensive inter-digitation of clones over time, and (3) the reproductive strategy of A. equina incorporates sexual reproduction with a planktonic dispersal phase.

Nearest-neighbour analyses applied to the distribution of phenotypes within this aggregation revealed several examples of auto-phenotypic under-dispersion. These results, together with (1) departure from Hardy–Weinberg equilibrium at a hexokinase locus, (2) evidence of linkage disequilibrium between hexokinase and malate dehydrogenase alleles, and (3) linkage between alleles at both these loci with a colour phenotype (grey pedal disc), all indicate that the genetic composition of this group of anemones had been strongly influenced by founder effects followed by clonal reproduction.

A comparative analysis of the size distributions of the various phenotypes and genotypes yielded few conclusions relating either to colonization history or to differential selection; reasons are given to account for this failure.

A study was made of the life cycle and reproductive ecology of Gammarus duebeni in the Test Estuary on the south coast of England. The species is towards the southern limit of its distributional range in the north-east Atlantic, which results in breeding continuing throughout much of the year. The breeding strategy employed was found to vary with season. The size of eggs produced and the rate of egg production were both temperature dependent, whereas the proportion of production expended on eggs and the number of eggs per brood, although probably influenced by temperature appeared to be controlled by food availability and female size. Factors affecting the mortality of eggs within the marsupium and breeding synchrony were considered in relation to season. The life cycle consisted of two major overlapping generations.

The shell strengths of seven species of barnacle were investigated by carrying out a series of compression and tension experiments. All species were tested under compression as solitary individuals. In addition the shell strength of crowded Semibalanus balanoides was determined. Results of the compression experiments show Balanus balanus and B. perforatus to be the strongest species with Verruca stroemia the weakest. All species were much weaker in tension than compression, particularly those with a calcified base, B. balanus being the weakest of the five species tested in this way.

The possibility of adaptive design of the barnacle shell to withstand wave action and predation techniques is discussed in the light of the results from the compression and tension experiments. Finally the importance of carrying out a wide range of tests of the shells when trying to determine their strength is discussed.

The extrinsic nerves of the stomach of dogfish and skates regulate the frequency and amplitude of contraction by inhibition followed by rebounds. By contrast the nerves of the spiral intestine are excitatory.

Stimulation of the vagus nerve of the ray produced slight reduction in the amplitude of spontaneous contractions of the cardiac stomach. Much greater inhibition was produced by stimulation of the sympathetic nerves and was followed by large rebound contractions. These effects were imitated by adrenalin and serotonin which altered the frequency and amplitude of contraction in various ways. These actions were not blocked by either propranalol (1–5 × 10−5 M) or phentolamine (2 × 10−5 M) and indeed were often increased. The excitatory response to adrenalin was not blocked by TTX even after this had blocked the response to the nerve. Responses both to the nerve and adrenaline were blocked by trazodone. Acetyl choline caused some contraction of the stomach but only at high concentration.

Muscles of the spiral intestine of Raja or Scyliorhinus were activated by stimulation of their sympathetic nerves and by adrenalin. These responses were not blocked by phentolamine and only reduced by propranalol They were blocked by trazodone. The response to adrenalin continued after the nerve was blocked by TTX. Acetyl choline had very little effect on the spiral intestine.

The striking differences between the responses of the stomach and intestine are probably related to the fact that the plexus in the latter contains no nerve cells. The neurons in the stomach are therefore presumbly connected with the inhibition and large rebound contractions.

Fertilized herring eggs were hatched in large sea water enclosures containing natural populations of phytoplankton and Zooplankton and the developing fish sampled at intervals for a period of 90 days to determine the levels and composition of their depot triacylglycerols. The percentage of triacylglycerols in total lipid declined from hatching to about 40 days post-hatch and then increased markedly during the remaining 50 days. During the first 30 days from hatching the acyl groups of the triacylglycerols were dominated by polyunsaturated fatty acids, especially 18:4 (n−3), 20:5 (n−3) and 22:6 (n−3), characteristic of a predominantly phytoplanktonic diet. For the remainder of the 90-day experiment the percentages of polyunsaturated fatty acids decreased, to be replaced by increasing percentages of 20:1 (n−9) and 22:1 (n−11 ) fatty acids characteristic of a predominantly zooplanktonic diet.

Populations of heterotrophic bacteria from a marine fish-rearing unit were estimated using a spread plate technique. Bacterial populations in winter were relatively low compared with counts in summer when the maximum water temperature was recorded. Almost 600 isolates were examined, and found mostly to be Gram-negative rods. The bacterial populations consisted of a diverse array of taxa, and the variations in total numbers were due to relative changes in the abundance of these. There were nine groups isolated exclusively from the surface of turbot, including Alcaligenes faecalis, Bacillus firmus, Photobacterium Angustum, P. logei, Pseudomonas fluorescens and unidentified Gram-negative rods. In addition, pure culture growth of Alteromonas haloplanktis and unidentified Gram-negative, budding bacteria were isolated from within the lesions of moribund turbot.

From bathyal depths in the Bay of Biscay, southwest of the British Isles, 89 species of polychaetes are described, among which are two new species, one new genus, and one new Combination, i.e. Pholoe fauveli sp. nov., Paracapitella southwardi n.gen., n. sp., and Galathowenia oculata, new combination. Of the species taken, 52 % are also known from abyssal depths. The bathyal polychaete fauna of the North Atlantic seems to be common with that of the Arctic and the North Pacific.

Samples of the deep-sea holothurian Ypsilothuria talismani were collected in a time series sampling programme from April 1978 to August 1981 at a 2200 m station in the northern Rockall Trough. The gonad of Ypsilothuria talismani lies beneath the dorsal body wall and the gonad tubules ramify throughout the body cavity close to the gut. In the female, there is no synchrony of gamete development between tubules although macroscopic observation suggests oocyte development is synchronous within each tubule. Maximum fecundity at any time is less than 50 oocytes per individual. The developing oocyte grows to a maximum size of 350 μm and is lined with accessory cells. Spermato-genesis is initiated at several nodes along the tubule with maximum sperm production at the periphery of each node. As spermatogenesis proceeds more of the tubule becomes active until, at maximum development, the tubule is a long digitate structure. We have found no evidence of seasonal reproduction throughout the time series samples. From the egg size, and fecundity we infer lecithotrophic development, with a reduced larval stage, for this species.

Sargassum muticum (Yendo) Fensholt was first described from Japan as the forma muticus (sic.) of S. kjellmanianum Yendo. Subsequently, s. kjellmanianum and S. miyabei Yendo have been recognised as conspecific with dioecious reproductive structures. S. muticum is monoecious. The taxonomic history of S. muticum and confusions arising are presented.

The spread of Sargassum muticum to regions of the world outside of Japan is illustrated. A distribution map of S. kjellmanianum, S. miyabei and S. muticum in the western Pacific is also presented with a discussion of this selected species group. Further work is required to determine the exact extent of S. muticum in the western Pacific region.

Three species of leptostracan malacostracous Crustacea occur in the Rockall Trough. The epibenthic Nebalia typhlops, previously recorded at depths of 200–500 m in the north Atlantic but to 1100 m in the Mediterranean, was found at depths of 1990–2925 m. The epibenthic Nebaliella caboti, previously recorded in the northwestern Atlantic at depths of 378 and 2085 m, was caught in the Rockall Trough at 1390–29000 m. The pelagic Nebaliopsis typica only occurred in samples from depths greater than 1500 m. A comparative study of the previously recognized species within the Nebaliacea is required.

Unfertilized eggs in the oviducts of female lumpsuckers are exposed to low oxygen tension (ca. 40% air saturation). After spawning and fertilization water agitation aids percolation of water through Cyclopterus egg masses, but early in development oxygen tensions within non-ventilated egg masses fall slowly because of the eggs’ low metabolic rate (consistent with their slow development – 40 days to hatching at 5 °C). There is a considerable increase in oxygen uptake at hatching; in this respect the lumpsucker resembles the herring, Clupea harengus.

Early stage eggs are tolerant of hypoxic conditions and can even survive brief exposure to anoxic sea water. Later eggs and larvae are much more susceptible to oxygen lack. However, fanning behaviour by the brooding male parent (usually assumed to be designed to promote oxygen uptake by egg masses) is almost continuous at the beginning of development but becomes less frequent later. It is suggested that the initial intensive fanning helps to drive off ammonia which is released as the eggs stick together.

The effect of changes in particle size and sediment depth on byssal attachment was assessed in laboratory experiments. Mytilus edulis did not attach byssus pads to mud or silt less than 0·85 mm in diameter, but did attach pads to gravel. On gravel more pads were attached to the substrate (mean = 19·44 threads/mussel/week) than to other mussels in the group (mean = 7·34 threads/mussel/week). Because no byssal attachment to the finer substrates occurred and preference for other mussels in the groups rather than the plastic of the holding tank was shown, clumps, characteristic of mussel beds in the field, were formed. The clumps became increasingly well defined as the depth of the substrate increased. Few clumps were formed on the coarsest substrate as a result of preferential byssal attachment to gravel particles.

Mytilus edulis attached more byssus threads to slate than to glass and more to glass than to p.t.f.e. in a given time period. This coincided with the order of polarity of the surfaces. On p.t.f.e., a non-polar plastic, the animals were most mobile, and were found to move off the surface in 3–5 days. Whilst on the polar surfaces, the animals clumped on glass, and remained relatively immobile on slate.

When a choice of surface for byssal attachment was provided, the largest number of pads was always attached to the more polar surface. The preference was as follows: slate/glass 2·80 : 1·00; slate/ 5·38 : 1·00; glass/wax 5·97 : 1·00. Although the preference for slate and glass over wax was numerically similar, there is a clear preference for slate over glass.

Specimens of Littorina littorea from unpolluted (Menai Bridge) and metal polluted (Restronguet Creek) sites have been analysed for ten metals in eight different tissues. The concentrations of metals in whole animals and in individual tissues have been subjected to linear correlation analysis to establish metal/metal and tissue/tissue interactions. The results indicate that copper and magnesium are accumulated independently by specific connective tissue cells. Group A metals are largely accumulated by the digestive gland whereas group B metals are concentrated by the kidney. At low levels of metals there may be competition for particular ligands but at higher levels of pollution new ligands may be induced in particular cells. The implications of these interactions are discussed in terms of cell physiology and related to the significance of the use of biological organisms as indicators of metal pollution.

Uptake and incorporation of [3H]glycine from 1 μM solutions was observed in the tissues of larval oysters, Crassostrea gigas, Ostrea edulis, and mussels, Mytilus edulis. In all cases, radiolabel first appears in the larva's velum. Following increasing exposure time, label begins to appear in other organs. In newly settled larvae of the oyster, C. gigas, and the scallop, Pecten maximus, uptake occurs via the developing gill buds. All experiments provide evidence of direct epidermal uptake of soluble nutrients without any participation of the digestive tract. Scanning electron micrographs show that there is no bacterial population visible on the surface of the velum that might act as an intermediate step in nutrient transport. These studies on veligers, pediveligers and settled larvae link the phenomenon of larval uptake with the extensive literature on the direct uptake of soluble nutrients by adult bivalves.

During five annual ground fish surveys of the North Sea, all the benthic invertebrates trawled at 48 primary stations were recorded. The data were subjected to classification analysis, which showed a basic division between northern and southern North Sea benthos. The southern North Sea was further divided into three benthic regions, and the northern North Sea into four benthic regions (including one to the west of Shetland). The factors influencing the faunal assemblages in the various regions were discussed.

The River Tamar and its tributaries drain a highly metalliferous area; and increased metal levels in river water might be expected to affect biological water quality in the estuary. In order to detect possible effects we have used sensitive responses to stress of the hydroid Campanularia flexuosa as an index of quality of water samples from the River Tamar, Plymouth Sound and Cattewater. No water samples caused inhibition of colonial growth rate, but in each experiment there were significant variations in other more sensitive responses. It is these variations that we have related to metal distributions, although of the metals measured, only copper and cadmium occasionally occur in concentrations that could be biologically significant, and at the same time show any correlation with the hydroid responses. The limitation of the survey to water of relatively high salinity does not permit a firm conclusion about the origin of these metals, but there are some indications that local inputs may be important.

Cod and plaice eggs show a gradually increasing rate of ammonia excretion during development and in neither species was there a great change in individual output at hatching. The rates of ammonia excretion recorded for cod and plaice larvae were similar to those recorded for planktonic Crustacea of comparable size by Conover & Corner (1968).

Lumpsucker eggs and larvae have a basically low rate of ammonia excretion (consistent with their slow rate of development and low oxygen consumption), but much ammonia was released from the eggs in the first day or two after spawning. This ammonia was of non-metabolic origin, but was not accumulated from the ovarian fluid prior to spawning. Lumpfish eggs become very sticky when they are first exposed to sea water, but this stickiness is lost within 24 h. Stickiness stems from a viscous elastic slime; it is suggested that the non-metabolic output of ammonia is caused by changes in the composition of the slime as the eggs are bound together in a lattice.

Lacuna vincta appeared at Musquash Head, New Brunswick, in large numbers from June to August 1981 principally on lower midlittoral and infralittoral fringe Fucus edentatus. The population reached a mean maximum of 280/m2 in June; by mid September the animals had disappeared. The L. vincta grazed heavily and deposited egg masses on Fucus edentatus but little on other species. All fine and filamentous and encrusting algal species and rock were avoided for egg deposition. Egg mass abundance peaked with the population in June with a mean of 180/m2. Mean egg production in June was 83000/m2.

Both snail and egg mass distributions were correlated with the percentage cover of F. edentatus, reaching a maximum at 40–75 cm above mean low tide level.

The snails ranged in length from 2–7 mm, consisting of three cohorts from different larval settlements. Growth was rapid in July averaging 0·6 mm/month slowing later.

The food plant Fucus edentatus showed a heavy impact of the herbivore. Weight reductions attributable to grazing rose from 56 % in June to 79 % in August and grazed plants tended to thicken rather than elongate with growth. Grazing removed about 79 % of the net production of F. edentatus which averaged 61 g dry wt/m2/day. The impact of the L. vincta population on F. edentatus seems extraordinarily severe.