Two new species of hydroid, Sarsia pinforma and Sarsia striata, Family Corynidae, have been found near Oban, west coast of Scotland. Their life-histories have been worked out and their medusae have been reared to maturity in the laboratory. Medusae of striata have also been found in the sea and hydroids have been reared from them. The hydroids and the stages of development of the medusae are fully described and figured, with observations on habits and comparisons with other species of Sarsia. Observations on the development of the gonophores of Sarsia occulta and comments on Sarsia densa are added.

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.

Suspension-feeding in the holothurian Neopentadactyla mixta (Östergren), 1898 is accomplished by an adhesive secretion synthesized in modified retractable discs of epithelial cells located on the terminal tentacular nodes. Besides secretory cells, each disc epithelium is composed of three other cell types: ciliated, granular and nerve cells. The fine structure and possible functions of the epithelium are described with reference to the behaviour of tentacles during feeding and the observations are compared with existing information on holothuroid feeding mechanisms.

The shape of such morphological characters as leaves and air vesicles of the introduced brown alga Sargassum muticum (Yendo) Fensholt were found to vary seasonally. A range of observations is presented together with a general description of European material.

The energetics of leaping (porpoising) in aquatic animals is investigated employing two simple hydromechanical models. The first compares the energy required for swimming at different depths below the surface with that for leaping, the second is employed to calculate maximum cruising speeds in fish and cetaceans for the cases of laminar and turbulent boundary layer flow. Leaping is energetically less efficient than swimming close to the surface up to a certain speed (crossover speed) after which it is more efficient. It is shown that dolphins ought to be capable of reaching the required crossover speeds even if subject to a turbulent boundary layer. This is not so for the larger cetaceans that have been observed to porpoise (e.g. killer whales, Orcinus orca). However, crossover speeds for leaping are well within their scope for the case of a boundary layer that is half laminar and half turbulent. Crossover speeds in pelagic animals that do not undulate a substantial proportion of their body in swimming (e.g. baleen whales and penguins) are relatively high. The crossover speeds of the baleen whales are about four times their observed cruising speeds. It is suggested that these animals swim at speeds at which their filtration apparatus (baleen) operates most efficiently. Pelagic fish do not porpoise and reasons are suggested for this.

Seasonal variations in the range of air vesicle and leaf shape upon the brown alga Sargassum muticum (Yendo) Fensholt provide some discrepancies with descriptions of material from the alga's indigenous Japanese and introduced British Columbian habitats.

Experimental observations indicate that mucronate air vesicles are most common at low (i.e. 10 °C) and high (i.e. 25 °C) temperatures, with those of 30 °C being injurious to plant growth. Air vesicles with spiked proliferations are also seen to increase in occurrence with an increasing light intensity at 20 °C. Excised ‘winter’ form leaves collected in February were able to regenerate ‘summer’ form leaves from their damaged bases, under culture conditions.

Field and laboratory investigations show that leaf and air vesicle shape tend to vary seasonally and may be experimentally changed by both temperature and light intensity. Such plasticity observed in the morphology of these characters in S. muticum raises doubts as to the taxonomic status of many species ascribed to the large genus Sargassum.

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.

Analyses of the cirratulid polychaete Tharyx marioni have shown that this species contains a high concentration of arsenic, its whole-body concentration usually exceeding 2000 μg/g dry weight, even when living under low ambient arsenic conditions. Similar levels of arsenic are present in both juvenile and adult worms. Other cirratulid species, such as Cirriformia tentaculata and Caulleriella caputesocis, from the same habitat contain low arsenic concentrations (< 100 μg/g dry weight).

Much of the arsenic in T. marioni (ca. 20 %) is contained in the palps which comprise about 4% of the body dry weight; in these organs, concentrations of 6000–13 000 μg/g dry weight have been measured. Some of the arsenic in the palps is bound with copper in granules but the bulk appears to be organically associated; extraction data indicate about 65% of the total arsenic is linked to the lipid pool with a further 25% being proteinbound arsenite (cysteine-extractable). The results of experiments using 74As suggest that most of the arsenic is derived from the sediments rather than the water but the mechanisms and functions of this arsenic accumulation by T. marioni remain to be investigated.

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.

Changes in the relative size of the ovary, oviducal glands and eggs are described for Eledone cirrhosa captured from the North Sea off Aberdeen over a 3 year period (N = 488). The analysis is based only on freshly caught animals, excluding those held in aquarium conditions (> 5 days). Ovary enlargement and egg size estimates are used as indices of sexual maturity. Between 0–15% and 18–95% of total body weight is contributed by the ovary. Maximum egg length in the ovary ranges up to 7 mm. On these criteria, sexual maturation typically occurs at body sizes between 400–1000 g although some animals of 1000–1200 g are found showing no evidence of ovary enlargement. The majority of the monthly sample is always immature but maturation can apparently occur at almost any time of the year. Increase in mean ovary index and mean values for egg size are strongly seasonal and indicate a peak incidence of sexual maturity over 2–3 months in the July-September period. Spawning is presumed to follow within 1 month. Estimates of the fecundity of the females, based on the egg sample from the ovary, range from 2·2 × 103 to 55 × 10 3 eggs with a mean of 11 × 10 3 and a mode of 7·5 × 10 3 eggs.

The endogenous activity rhythm of the estuarine amphipod Corophium volutator has been studied by direct observation and with the use of time lapse photography. The rhythm persists under constant conditions having a free running period of between 12 and 13 h, and with activity maxima occurring during the early ebb. Freshly collected animals show a rhythm which is modulated on a semi-lunar basis, the activity maxima being attenuated during the neap tide periods, and the rhythm has also been found to vary in definition throughout the year. The activity pattern is most clearly denned in early summer and autumn, the population becoming arrhythmic during the winter months. The rhythm is relatively unaffected by the ambient light intensity and temperature of the recording conditions, and is evident in all post-natal stages of development. The possibility of mutual entrainment is discussed.

Preliminary determinations of heavy metals in winkles Littorina littorea along a concentration gradient in the Fal Estuary suggested that whole body concentrations might be related to those of the water. When animals were transplanted to this heavily contaminated estuary, changes in tissue concentrations of As, Co, Cu and Zn were largely complete after 2 months.

Relations between the winkle and water concentrations may be indirect since its algal diet is thought to be the main source for most heavy metals. Data from a large number of United Kingdom estuaries were used to compare concentrations of 12 metals in L. littorea with those of the brown seaweed Fucus vesiculosus which forms part of its diet. Very significant relations were found for Ag, As, Cd and Pb, suggesting that since concentrations in the seaweed probably reflect those of the surrounding water, so also do those of the winkle. However, concentrations of Ag in the animal also appeared to be influenced by dietary Cu levels. In addition, significant relations between the two species were found for Cu, Fe, Hg and Zn, but the slopes were shallow, perhaps indicating regulation by the winkle. For Cr and Mn relations were not very significant and, for Co and Ni, concentrations in the winkle appeared to be influenced by those of Cu and Zn.

Compared with concentrations in L. littorea, those of L. littoralis from the same site were generally higher whilst in L. saxatilis they were usually of the same order or lower.

In assessing the winkle as an indicator of metal contamination the present results have been combined with those of other workers to produce comparisons between most estuaries in England and Wales. It is concluded that whilst the winkle is a useful indicator for Cd and a few other metals, it is certainly not a perfect indicator organism.

The annual cycle of some physiological conditions in the ormer, Haliotis tuberculata L. was studied by the C:N ratios of foot tissue which were convertible to the glycogen contents, and the coefficients of fatness calculated from two formulae. The former method showed the seasonal change inrelation to the reproductive cycle indicating the foot tissue as a nutritive storage reservoir for spawning, and the latter gave no clear seasonal fluctuation, except a drop of the value shortly afterspawning.

Comparison of ormer populations representing local sites in Guernsey was made by the two methods during the periods of gonad maturation, spawning and pre-spawning (May-October), and the shell forms were analysed by measuring three dimensions of shells, namely, shell length, width and height. The results revealed some changes in physiological conditions between different localities and seasons even within Guernsey. The shell forms also appeared to differ at each site probably as a reflexion of physical and biological conditions surrounding them. The relation of the results obtained by all the methods was discussed to give a more generalized account on physiological conditions of the ormer for its reproduction.

A new species of Listriella is described and figured from maerl deposits in Kilkieran Bay, Co. Galway. The holotype of the only other British species is figured for comparison. The amphipod fauna of Kilkieran Bay (Co. Galway) maerl is compared with that of Eddystone shell gravels.

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.

The endogenous rhythm of swimming activity shown by Corophium is reset by pulses of sub-zero temperature, the activity maxima being rephased to the time of rewarming at the end of the cold period. Chilling is not equally effective at all stages of the tide, pulses applied during the flood tide causing a phase delay, while those applied during the ebb advance the rhythm. Chilling at the time of low water induces arrhythmic swimming and it is suggested that the rhythm enters a state of equivocation at this time when an advance and a delay in phase are both equally probable. This results in the loss of synchronization between individuals and the disappearance of the overt rhythm from the sample population.

The development of the olfactory system, taste and sensory buds of the Dover sole (Solea soled) during metamorphosis has been studied by light and electron microscopy and preliminary correlations with changes in feeding behaviour have been made.

INTRODUCTION

During metamorphosis, the feeding behaviour of the Dover sole changes considerably. In the early larval phase, the fish swim pelagically, feeding on plankton using their visual sense, while the metamorphosed fish become more active at night, finding food by means of their chemical senses (for a review of the literature, see de Groot, 1971). However, previous observations have shown that sole are capable of feeding in the dark from the very early hatching stage (Blaxter, 1969) and also that at the time of first feeding, the majority of the larvae remain close to the bottom where they appear to ingest particles (Rosenthal, 1966; Fluchter, 1966).

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.

The tidal rhythm of swimming activity shown by the estuarine amphipod Corophium volutator can be entrained to cycles of temperature and immersion in the laboratory. The rhythm is phased to the period of increasing temperature, or to the time at which the animals are wetted by the artificial tide, and the activity maxima follow the Zeitgeber with a phase delay of about 5–6 h in each case. Entrainment to these variables alone is inadequate to account for ebb tide swimming in the natural state, and it is likely that the rhythm is normally entrained by a number of factors of variable significance.

Various neurotransmitters were injected into the blood supplying the brain of Octopus vulgaris and the effects, particularly on the chromatophores, were observed. l-glutamate, GABA, dopamine, noradrenaline and octopamine caused expansion of the chromatophores and darkening of the skin; ACh caused retraction of the chromatophores and paling; 5HT caused differential expansion and retraction: mottling. These responses, which are neurally mediated, were particularly well defined for ACh and 5HT and the effects of these drugs were studied in more detail. The paling effect of ACh was mimicked by nicotine but not muscarine and was partially antagonized by tubocurarine. The mottling induced by 5HT was transiently antagonized by methysergide maleate, as was ink-ejection and defaecation. Brain lesions to localize the sites of action of ACh and 5HT suggest that they act at the level of the sub-oesophageal lobes to control the chromatophores, but that 5 HT may act at the level of the optic lobe to control inking and defaecation. These results are related to the pharmacology and histochemistry of the cephalopod brain and to the organization of the chromatophore control system.