The circulation of the northern and north-eastern Celtic Sea, has been studied, using especially observations made in April 1950.

The Celtic Sea in that month was 0·5° C warmer than the average temperature 20 years earlier.

The following distinctive water masses have been recognized (i) Land's End water; (ii) South Wales coastal water; (iii) Carnsore corner current water; (iv) Nymphe Bank water, including a component enriched by up-welling off Waterford; (v) County Cork eddy water.

The South Wales coastal water, though rich in nutrients presumably derived from sewage effluents, was not very productive. A parallel is drawn with the Hyperion sewage scheme of the City of Los Angeles.

The low-salinity water present in the centre of St George's Channel in summer is attributed to flow from the coast of South Wales. In the autumn water is recruited more directly from the Celtic Sea.

The silicate content of the Carnsore corner current was half that in South Wales coastal water on the opposite side of the Channel.

Up-welling of water enriched by breakdown of bottom muds occurred off Waterford.

The drift system in the central Celtic Sea is dominated by the prevailing winds. The drift in April 1950 was a composite affair and it has been possible to dissect some of the components and to show how they interplay.

In about 7° W. long., a mixed water mass sets south from the Nymphe Bank and was identified for more than 100 miles.

A tentative explanation is offered for the distribution of compounds of phosphorus in terms of regeneration from bottom deposits.

Minke whale (Balaenoptera acutorostrata) surfacing intervals were recorded over a period of three years in the coastal waters of Mull, Coll and the Small Isles, in the north-west of Scotland. Significant differences in surfacing intervals were noted both throughout the day and throughout the year. Surfacing intervals were shortest at noon and in the months of June and July. Surfacing intervals were longest both mid-morning and mid-afternoon and during May and August. Differences in surfacing intervals were interpreted to be the result of ecological changes such as different foraging strategies. Consequently, the results of this study have an impact on the methodologies and designs of minke whale sightings surveys.

Vertical migration interacts with oscillatory tidal flows to produce horizontal transport. When the vertical migration period is an exact multiple of the tidal period then net uni-directional horizontal transport can occur. This happens most effectively in ‘selective tidal-stream transport’ for which vertical migration into the flow is specifically synchronized with the dominant (usually M2) tidal constituent. When migration and tide are not synchronized there is no net transport and, instead, a horizontal displacement oscillation of the organism takes place at the beat period between the vertical migration and tidal periods. The most common form of vertical migration is synchronized, not with the tide, but with the day-night cycle. Diel migration in M2-period tidal currents induces no net transport, but can produce excursions of several tens of kilometres over just a few days. Diel vertical migration can, however, interact with the sun-generated part of the semi-diurnal tide to produce net horizontal transport, the direction of which is controlled by the phase of the S2 tidal currents. The spatial distribution of phase implies that regions of horizontal convergence and divergence will result from diel migration. Diel migration in diurnal-period tides causes the preferred direction of transport to reverse at six-monthly intervals.

The recently described gutless Astomonema southwardorum Austen, Warwick & Ryan 1993, from North Sea methane seeps lives in symbiosis with oval, extracellular bacteria completely filling the lumen of a modified gut. The bacterial strand is tightly lined by a thin layer representing very long intestinal cells of the host. The bacteria are 5.5–6.0 µm in maximum length and 3.5–4.0 µm in width. In the anterior body the alimentary tract is completely reduced. The structure and size of the symbiotic prokaryotes, as well as their extracellular location in the lumen of a non-functional gut, differ substantially from those in A. jenneri, the single species of this genus thoroughly studied electron-microscopically (Ott et al., 1982). These structural discrepancies suggest a careful reassessment of the genus Astomonema.

Patterns of variation in the assemblage structure of butterflyfishes (Chaetodontidae) of the Red Sea and western Indian Ocean have been compared. There is a lower number of species in the Red Sea, a high proportion of which are endemic to the region, both features that have been attributed to the relatively recent origin of the Red Sea. In the Red Sea overall mean abundance of butterflyfish is greatest in the central part, decreasing both to north and south. Several species present in the southern Red Sea are absent from the north. By contrast, most western Indian Ocean species are widely distributed within the Indo-West Pacific. Comparative field studies in the northern Red Sea (Egypt) and western Indian Ocean (Kenya) showed that mean number of species was higher in the western Indian Ocean, but mean density of butterflyfishes was higher in the Red Sea. In both areas diversity of butterflyfish was related to mean substrate diversity (the number of coral growth forms). Mean spatial niche breadth of butterflyfish species was much higher in the Red Sea than in the western Indian Ocean, whereas the extent of microhabitat use was higher in the western Indian Ocean. It is suggested that these differences may be related to the more recent evolution of the Red Sea fauna.

Scales for stomach fullness and colour were developed and calibrated in order to provide an easy and reliable way to determine feeding intensity and food quality in sardines. The categories of the fullness scale reproduce the amount of food intake as indicated by the weight of the stomachs. The levels of the colour scale reflect the type of plankton eaten as shown by concentration of a-type phaeopigments and prey analysis of the stomach contents. Individuals of a wide length range were used in this study, leading us to suggest that these indices can be applied to the entire juvenile and adult sardine population. The use of the colour and fullness scales provides a rapid and efficient means of characterizing sardine feeding. Based on the colour and fullness categories of the stomachs the majority of stomachs were almost empty or at most half-full and the diet was composed of different proportions of phyto- and zooplankton items. As indicated by the prey analyses of the contents the most important constituent of the diet, in volume, were zooplankton prey.

The main functional characteristics of haemocytes from the common periwinkle Littorina littorea (phagocytic ability, acid phosphatase activity, cytotoxic properties and generation of reactive oxygen intermediates) were investigated. The blood cells of L. littorea demonstrated phagocytic activity for zymozan particles in both plasma and seawater. However, the level of phagocytosis in plasma was higher than in seawater, suggesting the presence of some soluble factors with opsonizing activity for yeast cell walls in the snail haemolymph. Acid phosphatase was detected in haemocytes following phagocytosis of zymosan. Zymosan particles as well as soluble inducers of respiratory burst (mannan, phorbol-myristate acetate, lipopolysaccharide from Escherichia coli) were shown to trigger superoxide anion production in L. littorea blood cells as evidenced by nitroblue tetrazolium (NBT) reduction. Haemocytes exposed simultaneously to both inducer and the superoxide scavenger enzyme—superoxide dismutase demonstrated a lower ability to reduce nitrobluetetrazolium. Periwinkle blood cells showed plasma-independent cytotoxic activity for human erythrocytes which may be due to the release of superoxide intermediates into the extracellular environment. These results, together with previously obtained data, suggest that haemocytes are the main effectors in the internal defence system of L. littorea, with humoral factors playing an accessory role in recognition and elimination of pathogens.

A specimen of the deep-water, spatangoid urchin, Cystochinus loveni, wearing a costume of agglutinated protists, was collected from 3088 m in the Gulf of Alaska, north-east Pacific. Over 24 putative taxa of living and dead foraminiferans and xenophyophores, as well as a sipunculan, polychaete, tanaid, and two isopods, were collected from the dorsal surface of this single individual. This is the first report of a deep-sea urchin using rhizopod protists and it is proposed that the urchin acquires camouflage or benefits from increased specific gravity associated with the protistan cloak.

Colonization of the littoral zone presents many problems to both sessile and relatively sessile invertebrates. These may be especially acute for inhabitants of the upper reaches of this zone, since suitable niches are usually sparsely distributed there, and are often ephemeral in nature. Consequently, both intraand inter-specific competition for space is likely to be particularly intense.

The widely distributed and abundant, beadlet anemone, Actinia equina L., in common with a number of other littoral anthozoans, is apparently capable of both asexual (apomixis or somatic embryogenesis; Polteva, 1963; Gashout & Ormond, 1979; Orr, Thorpe & Carter, 1982) and sexual (Carter & Thorp, 1979) reproduction. The former results in the production of young, which are brooded within the coelenteron and which appear most suited to local dispersal, whilst the latter, if it occurs, is assumed to involve either ovipary or larvipary followed by a planktonic phase. Study of this species therefore affords an opportunity to investigate the dynamics of colonization and dispersal in an heterogeneous environment, in relation to flexibility in reproductive tactics.

The seasonal changes in the foraminiferid populations along the Tamar-Eddy-stone profile have been shown for the winter, spring and summer of 1962. No single environmental factor appears to be wholly responsible for these changes but temperature is considered to be important. Variable salinities are of secondary importance in the Tamar. These seasonal changes have been compared with those observed at Christchurch and found to be different, presumably because of the different temperature and salinity conditions prevailing in the two estuaries.

A qualitative assessment of the energy input of the environment from the nature of the deposited sediment has shown a good positive correlation between the distribution of the Miliolacea and a high-energy environment. All other superfamilies show a negative correlation with high energy, but the Cassidulinacea show a preference for a moderate-energy environment during the summer.

Foraminiferids, found not to be very abundant in the Plymouth region, show a trend toward greater numerical abundance and greater diversity in passing out o t sea. The shortage of living foraminiferids is tentatively correlated with a restricted food supply.

Twenty years ago the Plymouth Laboratory investigated the spawning of mackerel and pilchard in the Celtic Sea. The physical background for their work, which the late Dr G. A. Steven and Mr P. G. Corbin sought, could not be provided since waters with similar temperatures and salinities evidently had very different physical and biological histories.

Study of type and other material using scanning electron microscopy has permitted the recognition of three new species and one new genus of Arctic and boreal calloporid anascans. Originally described from the Gulf of St Lawrence, Callopora whiteavesi is reassigned to Flustrellaria, a calloporid genus not previously reported extant. Material from north-east Greenland misidentified as C. whiteavesi is described as C. weslawski sp. nov. The new genus Septentriopora is introduced for calloporids lacking pore chambers, with a distolateral pair of small interzooidal avicularia that face proximally or proximolaterally, and a reduced ovicell. The type species of Septentriopora, Tegella nigrans, has frequently been misidentified. Many of the supposed records of this species belong to two other species, described here as Septentriopora karasi sp. nov. and S. denisenkoae sp. nov. The apparent ovicell in S. karasi is particularly unusual, being vestigial and kenozooid-like in morphology.

The present list of Polychætes is a revision of the list published in 1904, as part of the general list of the Plymouth Marine Invertebrate Fauna (Journ. Mar. Biol. Assoc., vol. vii., 1904, p. 219). It is the result of work carried on in the intervals of other researches, as opportunity offered, and there are in all probability a good many gaps still to be filled.

Three species of the polychaete genus Magelona are known from the neighbour-hood of Plymouth. One is the widely distributed M. papillicornis F. Müller, described first from the coast of Brazil (Müller, 1858) and subsequently frequently recorded for northern European coasts and the Mediterranean. Near Plymouth this species occurs in clean sand in the lower tidal region and offshore, as in Whitsand Bay. Of the other two species, one from clean sand near low water at Mill Bay, Salcombe, awaits description. The third has been known for many years but until now has not been recognized as an undescribed species. It was formerly abundant in the Rame Mud (a deposit of black sandy mud); thus Mare (1942, p. 542, as M. cincta Ehlers—a provisional identification by me) on 12 July 1939 found 120 per m, associated with large numbers of other polychaetes, lamellibranchs, etc. The locality was close to Ford's station No. 93 (Ford, 1923, chart facing p. 167, and p. 218 where the position is given as Rame Head, E. ½ N. Tregantle, N.½ E.). At this station on 20 February 1923 Ford had four specimens (recorded as M. papillicornis) from ⅕ m. On 11 August 1922 at station No. 53 close by (Rame Head, E., 1½ miles) he obtained thirteen specimens of the same species from 1/10 m, the substratum being black mud. Ford records papillicornis from other offshore mud or muddy-sand stations over a fairly wide area inside and outside Plymouth Sound, but in less abundance. It is certain that some of these records, especially those detailed above, are of the species taken by Mare and provisionally identified as cincta.

The regulatory framework of the red octopus (Octopus maya) fishery includes total allowable catches (TAC), which are based on studies conducted on the population that occurs in shallow waters. In fact, most of the biological studies of this species refer to the fraction of the population that occupies waters less than 30 m deep; however, O. maya can occur up to a 60 m depth. The aim of this study is to assess the stock of O. maya that occupies waters between 30 m and 60 m deep. Four research cruises were carried out during the closed and fishing seasons, from May 2016 to January 2017. An average of 29 sampling sites were surveyed in each cruise (±2 sampling sites) using a commercial vessel with a uniform sampling effort. In each sampling site, the swept area, the total number of octopuses captured, the total weight of the catch, and the individual weight of octopuses were recorded. Biomass was obtained with four methods: stratified random method, swept area method, geostatistical biomass model, and an unpublished method of weighted swept area. The four methods provided consistent results. The distribution pattern of species was in patches, although before the fishing season started it was more homogeneous. The fraction of the population that occurs between 30 m and 60 m deep consisted mostly of adult organisms, so it could be contributing significantly to the recruitment of the entire population, even to the fraction that is exploited.

The suggestion that the two chaetognath species Sagitta setosa and S. elegans were ‘indicators’ of different water masses was first made by Meek (1928), working off Northumberland, and subsequently developed by Russell (1933, 1935, 1939) in his classical work on their distribution as indicators of ‘Channel’ and ‘Western’ water off Plymouth. The alternation in dominance of the two species during the well-known changes in the Western Channel off Plymouth during the past 60 years (which have been termed the ‘Russell’ cycle; Cushing & Dickson, 1976) have most recently been reviewed and discussed by Southward (1984).

The spatial distribution, density, growth rate, longevity, mortality and recruitment patterns of the long-lived clam Arctica islandica in Belfast Lough, Northern Ireland, UK are described. The A. islandica population at Belfast Lough appears to be restricted to a small area at the mouth of the Lough. Additional searches for specimens further into the Lough and into deeper waters found no evidence of a larger more widespread population and we report population densities of 4.5 individuals m−2. The ages of the clams were determined from the number of internal annual growth lines in acetate peel replicas of shell sections. The population growth curve was fitted using the Von Bertalanffy growth equation: Lt = 93.7 mm (1−e−0.03(t–1.25)). Based on catch curve analysis, the Belfast Lough population has an estimated longevity of 220 years and a natural mortality rate of 0.02. We compare growth characteristics and life history traits in this population with other analogous A. islandica populations. The overall growth performance and the phi-prime index were used to compare growth parameters with data from the literature and we observed no significant relationship between the growth performance indices and longevity or latitude. Analysis of the age-structure and reconstructed dates of settlement indicate that this population has experienced almost continual recruitment over the last century with a gap in successful recruitment into the population 90–100 years ago and another 140–150 years ago. The size-structure revealed a scarcity of small individuals which we believe may be an artefact of the dredge sampling process.

The benthic system of the Golfo San Jorge was characterized from physico-chemical parameters based on samplings obtained during seasonal research cruises carried out on board the INIDEP vessels from springtime 1999 through wintertime 2000. Spatial and seasonal variations of temperature, salinity, density, oxygen content and chlorophyll-a in bottom water and concentration of total organic matter, total organic carbon, total nitrogen, chlorophyll-a and phaeopigments in sediments were analysed. The origin and nutritional value of the deposited organic matter were also assessed. The behaviour of the physico-chemical characteristics of the benthic habitat, studied applying statistical techniques, defined three sectors with particular characteristics and minimum seasonal variations: sector 1, the largest and deepest one, comprises the central area of the gulf and corresponds to a depositional environment; sector 2 comprises the areas next to the extremes of the gulf and corresponds to a flow or erosive environment; sector 3 includes the coastal area and south-east part of the gulf and belongs to a transitional environment.

The diet and feeding behaviour of the burrowing shrimp Alpheusmacellarius (Decapoda: Alpheidae) in sea grass beds in the Philippines were evaluated in the present study through field and laboratory activities. Sediment organic matter and sea grass appear to be important food sources for the shrimp based on the combined results of field surveys, gut content, stable isotope (δ13C) and sediment C content analyses. There was a significant positive correlation between organic matter content in the sediment and shrimp densities. In terms of behaviour, observations under controlled set-ups detected marked trends in duration and frequency of feeding. Feeding bouts became longer and more recurrent as the days progressed. Periodicity was exhibited with burrowing generally performed in the morning and feeding in the afternoon. A deposit-feeding mode was predominant in tank conditions as demonstrated by the shrimp's behaviour and burrow features.

Sessile organisms capable of asexual reproduction may be expected to show much genetic differentiation among local populations: mating between distant individuals is unlikely and genetic drift will contribute to differentiation since habitats can be colonized by one or a few individuals. This study investigates genetic differentiation of populations of the sea anemone Metridium senile (L.) in Great Britain. Individuals of M. senile are sessile and reproduce both sexually, by free-spawning of gametes, and asexually, by regeneration of fragments torn from the pedal disc. Metridium senile is one of the most common and widespread of British sea anemones (Manuel, 1981); reports place it at an enormous number and variety of sites around Britian (unpublished results of surveys by the Underwater Conservation Society of the United Kingdom). The extensive geographic range and variability of the species have confounded attempts to determine the taxonomic status of the ecological and morphological forms, but make it an interesting system for genetic analysis.