The reproductive morphology and larval development in Spionidae has been dealt with extensively by Soderström (1920), Hannerz (1956), Orrhage (1964). Simon (1967), Blake (1969) and Rice (1980). The family shows a considerable variation in gamete morphology, modes of sperm transfer and types of larval development. One might also expect variability in features of the life history patterns, such as the life span, reproductive age, reproductive cycles and fecundity, both between and within species.

Previous population studies on spionids include the work on populations of Polydora ciliata (Johnston) (Dorsett, 1961); (Daro & Polk, 1973), on populations of Scolelepis squamata (Müller) (Joyner, 1962); (Richards, 1970), on a population of Scolecolepides viridis (Verrill) (George, 1966) and on a laboratory reared population of Malacoceros cf. fuliginosus (Guérin, 1973). The present paper is an attempt to analyse the patterns of life history as they appear in littoral populations of Spio martinensis Mesnil, Polydora ciliata (Johnston), Pygospio elegans Claparede and Malacoceros fuliginosus (Claparède) at localities in N. E. England. The main features considered here are the changes in the size (age) distributions, the annual cycles of reproduction, the output of offspring and population density changes.

The Spio species in the population at Black Middens, North Shields, which is referred to S. martinensis Mesnil (1896) in this paper, was previously referred to S. filicornis (Müller, 1776) by Brady (1943). This species is identical to Mesnil's species, both in morphology and with regard to known biological features, while S. filicornis differs from it morphologically and its distribution pattern (Hannerz, 1956; Rasmussen, 1973; Wolff, 1973, Gudmundsson, in preparation).

Seasonal changes in the rate of shell formation frequently affect the surface morphology of molluscan shells, with reductions in feeding activity and calcification rates at low temperatures producing winter rings that can be used for age determination. Such annuli are well-known in lamellibranchs and have greatly facilitated studies on their growth, longevity and other age-related processes (as reviewed by Wibur & Owen, 1964; Rhoads & Panella, 1970; Comfort, 1957, 1979). However, they occur less frequently in gastropods and many species that do show such checks are relatively short-lived, or else their growth ceases or becomes erratic on sexual maturity.

The Vestimentifera, or deep-sea tube worms, comprise an ecologically and anatomically unusual group of marine invertebrates, with poorly understood biogeography, ecology, phylogenetic affinities and evolutionary radiation. To gain insight into evolutionary diversification within the group, we have used a molecular biological approach. We report the cloning of a region of 28S ribosomal DNA from representatives of five vestimentiferan genera plus, for comparison, a polychaete and a perviate pogonophore. Phylogenetic analyses using these DNA sequences confirm that Ridgeia and Tevnia are closely related genera. The analyses also lead us to propose the hypothesis that the earliest vestimentiferan lineage to diverge gave rise to the genus Lamellibrachia only. In addition, our comparative DNA sequence data now provide a means to use molecular methods for identification of deep-sea tube worms; we employed this approach to demonstrate that the first vestimentiferan specimen from the eastern Atlantic Ocean belongs to the genus Lamellibrachia. DNA-based identification should have wide applications in the study of vestimentiferan biogeography and ecology.

This investigation of the ultrastructure of the cells of laminarian haptera is part of a more detailed study of the growth of marine macroalgae and their inter-action with the environment. A major section of the programme is an attempt to establish the relationships between physiological, biochemical and structural (including ultrastructural) changes which occur during cell growth in brown algae and to compare such observations with those recorded for higher plant cells.

The choice of haptera (PI. IA) for much of this work on brown algal cell growth is based on their suitability for the interpretation of enzymological data on a cellular basis. Hapteron growth shows several convenient similarities to that in primary meristems of higher plants. Although lamina growth is from an intercalary meristem at the base of the lamina (transition zone), hapteron growth is essentially apical (Reinke, 1876), and differentiating cells are arranged in rows leading backwards from the apex (PI. IB, c). Thus, progressive sections cut from the tip backwards will contain an increasing percentage of vacuolate, elongating cells, as in the flowering plant root.

Brood protection is characteristic of the Spirorbinae although the mode of protection differs widely between species (Bailey, 1969; Knight-Jones, Knight-Jones & Vine, 1972). The way in which these protected eggs are successfully fertilized has been a subject of speculation (Gee & Williams, 1965; Franzen, 1956; Potswald, 1968). Individuals of the Spirorbinae are simultaneous hermaphrodites and the possible role of self-fertilization in their reproduction has been considered (Gee & Williams, 1965; Potswald, 1968). In the past, these problems have been discussed with the tacit assumption that no spermatheca is present in the Spirorbinae.

In fine muds such as those covering most of the bottom in the deeper parts of the Clyde Sea Area the formation of fæcal pellets is a factor of great biological importance. In these muds up to 40 per cent of the fine material is often consolidated into fæcal masses, and in extreme cases even the whole of the mud may be in the form of pellets. The significance of this process is clear. In the first place, the effective particle size of a large proportion of the mud is very greatly increased, and this in turn affects such characters as the porosity of the bottom, and the liability of the material to be transported by currents. In the second place, among selective feeders such as Syndosmya alba, which feed on the mud, there is an economy of labour, in that food which has once passed through the gut is set aside in a form in which it will be refused if again taken in by the siphons. This latter process can readily be seen in the example cited whose rejecta on examination prove to be almost entirely composed of pellets of its own and other species.

Many experiments have been made in the laboratory by different workers to study the swimming behaviour of plankton animals in relation to light and other factors. At the present time the special apparatus described by Hardy & Bainbridge (1951) is being used for a study of vertical migration, and other experimental work on the inter-relationships of zooplankton and phyto-plankton (Bainbridge, 1949) is also in progress. Both this type of work and current theories (see Cushing, 1951) on the migrations of zooplankton make it of some consequence to learn the actual nature of the movements of these animals in the sea itself; and it is of special importance to compare their swimming behaviour in the different types of apparatus with their behaviour in the sea.

A well-marked seasonal cycle in the total calcium content of the plasma was shown to occur in adult cod, Gadus morhua L., of both sexes: these changes were not found in juvenile, immature cod. The changes in concentration of plasma total calcium appeared to be associated with gonadal maturation, the period of hypercalcaemia coinciding with the maturation cycle and the plasma calcium falling to a resting level again after spawning. Seasonal changes were greatest in the female cod and it is suggested that the raised level of calcium is associated with vitellogenesis in the ripening ovary, probably under the influence of oestrogens. The cycle in the male is not yet fully understood.

The distribution of Lepeophtheirus salmonis larvae in Killary Harbour was investigated by taking plankton tows from a number of stations on a regular basis during the spring/summer period in 1995 and 1996. Current patterns, ovigerous lice loads on the resident fish and water temperature and salinity were also recorded during the study. Larvae were only found consistently at a station close to a salmon farm at the mouth of the harbour. In the inner harbour, close to the mouths of two rivers, larvae were recovered in sporadic time blocks. Highest densities of larvae were found at the beginning of the study in both years in the inner harbour with a subsequent decrease in the following months. The distribution, density and origin of the larvae are discussed in relation to the prevailing current patterns in the harbour, the ovigerous lice loads on the resident fish and the requirements of the larvae to locate a new host and complete the life cycle.

In the coxal region of Eupagurus bernardus the following receptor organs have been found: (1) a muscular receptor spanning the thoracico-coxal articulation, its innervation, in which several neurons take part, being arranged on a similar pattern as in Carcinus; (2) two innervated elastic strands running along the bundles of mm. levator and depressor basipoditis respectively and inserting into the tendons of these muscles; (3) a coxo-basipodite receptor consisting of connective tissue strand with numerous bipolar nerve cells ending on it. With the exception of the coxo-basipodite receptor, all sensory neurons of these organs have their cell bodies located in the central nervous system.

It is suggested that these receptors convey impulses elicited by the movements of the legs and some hypotheses concerning the role of each of them are put forward.

The distribution of deep-water (150–4850 m) benthic and bentho–pelagic cephalopods in the north-east Atlantic is described, based on 592 specimens collected from commercial and research trawling. Thirty-six different species of cephalopod belonging to 14 families were identified, though problems remain with the taxonomy of some of the octopod genera. At the shallower depths (150–500 m) sepiolids were the most abundant group with five species identified. Sepiola atlantica, Sepietta oweniana and Rondeletiola minor were restricted to the shallow depths (<300 m), but Neorossia caroli (400–1535 m) and Rossia macrosoma (205–515 m) extended into deeper water. The squids Todaropsis eblanae and Loligo forbesi were also common in shallow areas (<250 m). Among the incirrate octopods, Eledone cirrhosa was found at depths of 208–490 m. Three putative species of Benthoctopus and two of Bathypolypus were identified occupying depths of 250–2700 m. Graneledoneverrucosa was caught at depths of 1785–2095 m. Cirrate octopods dominated the cephalopod catch from the deeper areas, with Opisthoteuthis massyae occurring from 877 to 1398 m, O. grimaldii from 2165 to 2287 m, Stauroteuthissyrtensis from 1425 to 3100 m, Cirroteuthismuelleri from 700 to 4854 m, Cirrothauma murrayi from 2430 to 4850 m and Grimpoteuthis (five putative species) from 1775 to 4877 m. Abundance estimates of the more frequently caught species were calculated from swept areas of trawls and sledges in the Porcupine Seabight and on the Porcupine Abyssal Plain.

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.

Previous work on the biology and distribution of Calocaris is discussed briefly. The distribution in Northumberland waters is considered in relation to depth and bottom sediment.

Quantitative monthly samples show that population numbers remain very stable throughout the year. A well marked egg-laying period occurs in January-February when relatively few eggs (average 38) are attached to the pleopods. Eggs are carried for 8–9 months and hatch in September-October. By a combination of size-frequency distribution and gonad-developmnt classification the age-groups in the population are interpreted. After passing through a phase of testes development and spermatophore formation individuals lay their first batch of eggs at the end of the 5th year. The ovaries regenerate over a 2-year period and a second egg-laying takes place at the end of the 7th year with a possible third at the end of the 9th year.

The incidence of soft individuals in the samples together with observed changes in the coverage with epifaunistic growths indicate that after entering the 5th year a single annual moult cycle begins with a slowing down in growth rate.

Population numbers, fecundity and larval survival are discussed. Both the survival curve and the apparent lack of serious predation suggest that the population reaches senescence

Studies on the distribution of epifaunal species on their host have concentrated on those of plants, particularly laminarian algae (Fowell, 1939; Ebling, Kitching, Purchon& Bassindale, 1948; Sloane, Ebling, Kitching & Lilly, 1957; Scarratt, 1961, Ph.D. Thesis, University College of Wales, Aberystwyth; Norton, 1971), Sargassum algae (Kato et al., 1961; Nishihira, 1971; Ryland, 1974) and eel grasses (Nishihira, 1968; Nagle, 1968). Recently, however, the distributions of the animals living on ascidians Microcosmus sp. (Monniot, 1965) and the bryozoan Flustra foliacea (L.) (Stebbing, 1971) have been investigated.

The marine plankton contains an extremely diverse assemblage of ciliates which may be important in planktonic energy flow (e.g. see Burkill et al. 1987; Porter et al. 1985; Rassoulzadegan & Sheldon, 1986; Sherr & Sherr, 1987; Stoecker, Michaels & Davis, 1987; Verity, 1987). Many marine ciliates are delicate in nature and until recently have been poorly collected. Thus, they are often entirely missed in plankton sampling. During an investigation of the role of planktonic ciliates at the Isles of Shoals, Gulf of Maine (Montagnes & Lynn, 1988; Montagnes, Lynn, Roff & Taylor, 1988) samples were Bouin-fixed to preserve these delicate species. The ciliates were subsequently quantitatively protargol silver-stained to estimate species abundances and biomass (Montagnes & Lynn, 1987). This staining method, in addition to providing quantitative estimates of abundance and cell volume, gives invaluable taxonomic information by revealing cellular structures. Thus, it has been possible to compare the ciliates from the Gulf of Maine with described species.

An undescribed species of the genus Didemnum (Didemnidae) reported from installations in Whangamata Harbour (Coromandel Peninsula), has a unique and conspicuous three-dimensional growth form (possibly associated with vertical and undersurfaces it occupies). It is also distinguished by a combination of the few characters available to define these small, simplified, convergent organisms. Its stellate spicules are sparse except for a patchy layer in the surface test, primary common cloacal canals are the full depth of the zooids, nine vas deferens coils surround the testis, the gut is long forming a double loop, and larvae have six pairs of ectodermal ampullae. Eleven species said to belong to this genus have previously been reported from New Zealand, but only six are valid Didemnum spp., and they all are distinguished readily from the present species. Nevertheless, there is no evidence that the new species is introduced, and the simplest explanation of it occurrence is that it is part of the little known indigenous didemnid fauna of New Zealand.

In the last few years the exceptionally large monothalamous arenaceous rhizopod,Astrorhiza limicola Sandahl, 1858, has been collected in appreciable numbers from the Blythand Plymouth areas of British coastal waters. These collections of the living animals have enabled the authors, both independently and jointly, to make certain observations of the behaviour of the animal, and of the structure of the test, which have not been appreciated hitherto. With the exception of two early accountsof A.limicola, one by Bessels (1875) under the name Haeckelina gigantea and the other by Schultz (1915), very little appears to be known of the biology ofany member of the family Astrorhizidae.

During the last 3 years a survey of marine lipids has been in progress in this laboratory. Several classes of marine animals have been analysed for their fatty-acid composition. These results have shown a considerable species variation but no estimate could be made of the effect of season and environment. It was therefore decided to choose an inshore animal, which could be readily collected, and to examine its lipid composition with regard to seasonal and environmental changes.

The brackish-water, partly planktonic mysid, Neomysis integer (Leach), was selected. This species has already been the subject of much biochemical study (Raymont, Austin & Linford, 1964, 1966, 1968; Linford, 1965), in which the three major fractions protein, lipid and carbohydrate were examined. The lipid weight was found to be low in comparison with the protein content. Also, significant decreases in the lipid were found in November, January and March. It was concluded that N. integer stored little lipid as a metabolic energy reserve, and as the carbohydrate was low, protein may be catabolized. Only one sample analysis for fatty-acid composition was reported.

The marine species Neomysis nakazaviai has been investigated by Yamada (1961), but unfortunately an ether extract was taken from sun-dried material and so the results are not comparable with the present work on Neomysis integer.

In the present study the saponifiable fraction of the lipid is examined in more detail in an attempt to establish the relative importance of the factors of season, temperature and salinity upon the fatty-acid composition.

Laboratory experiments on feeding and respiration were carried out with the copepod Temora longicornis in the Clyde sea-area. In feeding experiments, a method using radiophosphorus as a tracer was employed. The filtering rate was very variable and is probably related to size. There seemed to be a seasonal variation in filtering rates. During the summer of 1961 weekly water samples were taken for estimation of the particulate carbohydrate in the sea. There was always enough food present for Temora. Respiration was measured by using a modified Winkler method. Oxygen consumption was related to surface area, and corrections in respiratory rates were made for the size differences in the animals used. Respiratory rates were very high at the beginning of an experiment, but after a sharp fall the rate became steady in about 30 h. An indication of seasonal variation in oxygen uptake was found.

The reproductive cycle of a local population the aspidochirote Holothuria tubulosa in Kaštela Bay (Adriatic Sea) was analysed from July 1994 to August 1995 by histological examination and observations of macroscopic features of the gonads. Five gonadal stages were described: recovery stage, growing stage, mature stage, spawning stage, and post-spawning stage. The distinguishing features used to describe gonad stages in both sexes included the main features of reproductive cells and gonad wall. The reproductive cycle showed a clear annual pattern and was synchronous in both sexes. Spawning occurred during the warm season, from July to September, when the surface water temperature ranged from about 22°C to 26°C. From October to January individuals were in resting phase and had no gonads. In both sexes, variations in maturity indices were related to the seasonal changes in temperature.