A large number of nanoplankton species originally found in the sea around Britain have now been collected from other northern temperate waters (see Leadbeater, 1972 c; Manton & Leadbeater, 1974). It was, therefore, of considerable interest to collect nano-plankton from warmer waters such as those of the Adriatic and Mediterranean. The larger plankton of both the Adriatic and Mediterranean has been the subject of investigation by a succession of scientists from many countries (for references see Tregouboff, 1952). Whilst many workers acknowledged the importance of the smaller plankton from these areas (e.g. Bernard, 1958; Lalami-Taleb, 1971) only a few have attempted to study and identify species belonging to this group. In this respect the meticulous work of Lohmann (1902a, 1911) and Schiller (19136, 19256) requires special mention. Lohmann (1902a), working on the phytoplankton from the coast of Sicily, first used the technique of pumping sea water through filter paper and in this way he was able to collect and identify many minute species for which he later suggested the name ‘ Nannoplankton’ (Lohmann, 1911). On a later excursion to the Atlantic Ocean, Lohmann (1911) found the gentle centrifugation of sea-water samples was a more satisfactory and less destructive way of concentrating small cells. Schiller's most important contribution concerns a phytoplankton study carried out as part of an international hydrobiological survey of the Adriatic Sea during the years 1911–14. Schiller's findings confirmed many of Lohmann's previous observations and added a further range of new species including many green flagellates (Schiller, 1913 6, 1925b).

1. A method, due to Poole & Atkins, is described for computing the total available energy at any depth in the sea, in joules or g.-cal.

2. The oxygen production of pure cultures of the diatom Coscinodiscus excentricus Ehr. was measured by the Winkler method after exposure of the diatoms in bottles at known depths in the sea. 3. The results of simultaneous measurements of oxygen production and of energy are given for 6 days in July and August 1933 and 1934.

4. Factors, other than light, that might affect the rate of oxygen production in the experiments are discussed and shown to be negligible. It is assumed that diatoms can use energy for photosynthesis equally well in all parts of the visible spectrum.

5. When the energy flux during the exposures is less than 75 joules or i-8 g.-cal. per cm.2 per hr., the oxygen production is directly proportional to the energy. The utilization of the available energy then amounts to about 7%.

A micro-analytical scheme for the determination of protein, carbohydrate, lipid and RNA levels in marine invertebrate larvae has been described in a previous paper (Holland & Gabbott, 1971). This addendum describes minor modifications to the scheme so that the level of DNA may be determined and includes a different procedure for the determination of RNA by u.v. absorption. DNA and RNA levels were determined in a number of nauplii and veliger larvae.

Adult plaice (Pleuronectes platessa L.) in the southern North Sea use selective tidal stream transport to migrate between their summer feeding grounds and winter spawning grounds. The fish come up into midwater when the tidal stream is flowing in one direction, but remain on the bottom when it is flowing in the opposite direction. This behaviour can theoretically save energy, which can be used for growth or reproduction. Alternatively, it may provide a transport system by means of which fish that have no ability to navigate over long distances can be conveyed reliably between their feeding grounds and spawning grounds.

Nematode species from three intertidal assemblages (St Lawrence Estuary, Quebec, Canada) were studied in order to form an ecological interpretation of three allometric attributes: body width, size spectra, and morphotypes. The three assemblages were characterized by a very similar sediment grain median (Md) but different silt–clay proportions: A1 (upper-tidal level; Md=122 μm; silt=34.8%), A3 (mid-tidal level; Md=182 μm; silt=12.8%), and A5 (lower-tidal level; Md=122 μm; silt=6.8%). Silt–clay proportions were an influential factor in determining the mean nematode body width, used as a morphological discriminant between burrowing and interstitial organisms. A plot of the number of species vs the body width-classes showed two peaks: between 19.3 and 22.6 μm (interstitial), and between 32.0 and 45.5 μm (burrowers). As for the size spectra, in sandy sediments the mean nematode individual biomass was smaller than in muddy sediments. As a consequence, the estimated mean individual respiration rate was greater in muddy (A1=2.26 nl O2 h−1) than sandy sediments (A3=1.25 nl O2 h−1; A5=1.12 nl O2 h−1). In contrast, estimated metabolic ratios were lower in A1 (2.78 nl O2 h−1 μg−1 dry weight, DW) than in A3 (2.95 nl O2 h−1 μg−1 DW) and A5 (3.01 nl O2 h−1 μg−1 DW) suggesting different productivity and/or physiological adaptations to different lifestyles (burrowing vs interstitial) between species inhabiting muddy or sandy sediments. Morphotypes (body width/body length ratio=w/l ratio) were found to be associated with feeding groups. Small w/l ratios were typical of microvores, while greater ratios were typical of epigrowth feeders and predators. Ciliate-feeders, deposit-feeders and facultative predators had intermediate ratios. A morphotype food-related hypothesis is proposed: the species morphotype reflects the quality of exploited food; a small w/l ratio (i.e. long gut) would favour digestive efficiency and would be an adaptation to low quality food (microvores); inversely, a greater w/l ratio (i.e. short gut) would be an adaptation to high quality food (epigrowth-feeders and predators).

This paper presents data on the incidental catch of sea turtles in both the Brazilian exclusive economic zone and adjacent international waters (both areas are located mainly in the south-western Atlantic) by Brazilian commercial pelagic longliners targeting swordfish, tuna and sharks. Data were obtained by on-board observers for 311 trips carried out in 2001–2005, totalling 7385 sets and 11,348,069 hooks. A total of 1386 sea turtles were incidentally captured in the five years (some of them were considered dead at capture): 789 loggerheads (Caretta caretta), 341 leatherbacks (Dermochelys coriacea), 45 green turtles (Chelonia mydas), 81 olive ridleys (Lepidochelys olivacea) and 130 of unknown species. Taking into account the distribution of the fishing effort in the study area and the incidental catch of sea turtles, four regions were highlighted for the analyses: Zone 1 is located off the northern Brazilian coast; Zone 2 is located off the central Brazilian coast; Zone 3 is the region off the southern Brazilian coast; and Zone 4, located in the open sea almost totally within international waters, is the region around a chain of undersea mountains known as the Rio Grande Rise (Elevação do Rio Grande). There is no information on the origin (nesting areas) of the captured olive ridleys, but there is some evidence, obtained through genetic and demographic analyses, that loggerheads, leatherbacks and green turtles inhabiting the open ocean around Brazil originate from nesting areas in several countries. Together with the fact that the south-western Atlantic is fished by longliners again from several countries, this places the conservation of sea turtles in that part of the ocean in an international context. Some conservation actions carried out by Brazil concerning the interaction between pelagic longlines and sea turtles in the study area are described.

INTRODUCTION

There are more than twenty species in the genus Neomysis Czerniavsky, of which the only British representative is N. integer (Leach). This is one of the commonest species of mysids round the coasts of Britain. It lives in estuarine, brackish-water situations and Tattersall & Tattersall (1951) have summarized its distribution. The present investiga- tion has added many records from the west coast lochs of Scotland: Lochs Striven, Riddon, Fyne, Gilp, Ranza in the Firth of Clyde; Lochs Craignish, Feochan, Etive, Creran, Shuna, Linnhe, Eil and Torridon farther north. The biology of Neomysis species is much better known than that of species in other genera:N. americana (Smith) has been studied by Cowles (1930), Whiteley (1948), Hulburt (1957) and Hopkins (1965); the biology of N. awatschensis (Brandt) has been examined by Ii (1964) and Turner & Heubach (1966), that of N. czerniawskii Derjavin and N. intermedia (Czerniavsky) by Ii (1964), that of N.japonica Nakazawa by Ishikawa & Oshima (1951) and Ii (1964), that of N. rayii (Murdoch) and N. spinosa Nakazawa by Ii (1964).

INTRODUCTION

Molluscan age determination has long been the subject of both biological and paleonto-logical research (Mossop, 1922 a, b; Haskin, 1954; Merrill, Posgay & Nichy, 1965; Andrews, 1972). Several workers have listed difficulties associated with traditional methods of determining the age of an organism based upon surface shell morphology (Pannella & MacClintock, 1968; Farrow, 1971, 1972; Berry, 1971). Others, such as Craig & Hallum (1963) have attempted, with moderate success, to circumvent these problems statistically by using size-frequency relationships, but such methods are of little value in age analysis of isolated individuals. The principal difficulty encountered in shell surface analyses arises from an inability to distinguish spawning and disturbance lines from annual marks. Problems associated with this separation have been reduced over the past decade by the discovery of daily and tidal periodicity structures within the shells of numerous Recent and fossil species of pelecypods (Barker, 1964,1970; Pannella & MacClintock, 1968; Clark, 1968; House & Farrow, 1968; Farrow, 1971, 1972). The biological and paleontological significance of such growth increments have been discussed at length by Pannella & MacClintock (1968), Barker (1970), and Clark (1974). When present in continuous sequences, these periodicity structures facilitate an accurate age determination of individual specimens.

An investigation into the histochemistry and ultrastructure of the digestive gland of Elysia viridis has revealed the presence of two types of epithelial cells, one of which contains numerous, structurally intact algal chloroplasts. Chromatographic studies indicate that these chloroplasts are derived from the animal's specific food, the alga Codium tomentosum. Following ingestion by the animal these do not appear to be digested or excreted, but accumulate and are maintained in the digestive cells. Autoradiographic studies suggest that they may be of some benefit to the animal as symbiotic organelles. Such a phenomenon may prove to be widespread among related species of Opisthobranchia.

Crisp & Meadows (1962, 1963) have shown that aqueous extracts of whole barnacles, when applied to an inert test surface renders the surface attractive to barnacle cyprids thus simulating the gregarious response displayed at settlement. The factor responsible for promoting the settlement of cyprids of Balanus balanoides has been shown to be nondialysable, resistant to boiling in aqueous solution, and can be fractionated by precipitation with ammonium sulphate (Crisp & Meadows, 1962, 1963; Gabbott & Larman, 1971). In their 1962 paper, Crisp & Meadows showed that the settlement factor was present in untreated extracts of all the arthropod groups they examined (including Carcinus maenas) and in extracts of two species of sponges and the fish Blennius pholis. Extracts of other animals and plants were not active. In particular, untreated extracts of the bivalves Mytilus edulis and Ostrea edulis were inactive when assayed against cyprids of B. balanoides. Recently one of us has shown that boiled extracts, partially purified by precipitation with ammonium sulphate, of whole barnacles (B. balanoides, Elminius modestus and B. hameri), crab carapace (Carcinus maenas), whole heads of the blenny (Blennius pholis) and of the body tissues (excluding the shell) of O. edulis and M. edulis, all contain a characteristic group of acidic proteins, or protein-carbohydrate complexes, with iso-electric points in the range pH 4.0–6.0 (Larman, 1975). This finding has prompted us to re-examine the specificity of the settlement response in barnacles.

Inspection videos of four offshore platforms in the central and northern North Sea were used to study the development of fouling communities on clamps and guides of oil export risers over an 11-y period (1989–2000). Results from multivariate analyses (multi-dimensional scaling and analysis of similarities) indicated that distinct assemblages developed in different geographical locations. These differences were mainly due to the protracted development of the Metridium senile (Cnidaria: Actinaria) zone on the northern sector platforms. The vertical zonation of fouling organisms was similar on all installations, although the water depth at platform locations varied from 80 to 169 m, indicating that fouling organisms display a wide bathymetric tolerance. This study has highlighted the value of long-term data present in operational inspection videos for the study of fouling communities.

Ciona intestinalis (L.) is probably the most cosmopolitan species of ascidians and has long been of general interest. The adult morphology has been well described in monographic form by Roule (1884), the physiology of the heart and circulation by Heine (1902), Enriques (1904) and Wolf (1932), of the nervous system by Magnus (1902), Hecht (1918, 1926), Cate (1928), Haffner (1933), and Bacq & Florkin (1935), and of the digestive system by Yonge (1925). Developmental studies include that of the early embryology by Conklin (1905), problems of fertilization by Morgan (1945) and Damas (1899,1900). In no work, however, has there been a presentation of the entire Ciona organism from the tadpole stage through the critical post-larval stages to the young cionid ascidian. The present account portrays this period of development, together with a discussion of some significant but relatively obscure aspects of adult structure.

Eggs and theRearing ofCiona intestinalis

While ascidians in general are difficult to rear to maturity under laboratory conditions, Ciona is relatively easy, and together with Botryllus schlosseri (Pallas) and Diplosoma gelatinosum (M.-Edw.) is liable to appear more or less spontaneously in large aquaria into which tadpoles may have been brought. Artificial fertilization is readily accomplished, and at almost any time of the year, since Ciona is sexually mature above a certain size and reproduction is seasonal only to the extent of the rhythm of the growth cycle. Normally eggs are set free spontaneously at dawn, although individuals kept in the laboratory may accumulate eggs and the oviduct become swollen.

Rotifers are microscopic aquatic animals that comprise more than 1800 species. Most rotifer species live in freshwater and limno-terrestrial habitats, while thalassic environments (brackish+seawater) are thought to host few species. No recent review of saline rotifers is available. Here we report the results of a review of the literature concerning rotifers from saline environments, distinguished into three categories: stenohaline, euryhaline, and haloxenous, and found both in truly marine habitats and/or in inland saline waters. A total of about 200 studies, mentioning fully identified rotifers from saline waters, allowed us to list as many as 443 rotifer taxa at either specific, subspecific and infrasubspecific rank, corresponding to 391 nominal species. Truly thalassic taxa, not found in inland saline waters only, accounted for 289, including the ‘stenohaline’ (143) and the euryhaline (146) ones. As for freshwaters, the majority of the thalassic rotifers inhabit the psammon, or display a benthic–periphytic way of life, while the plankton likewise is less species rich and less abundant. The geographical distribution of the brackish and marine rotifers largely reflects the distribution of rotifer investigators, therefore, no biogeographical analysis can be performed yet. In conclusion, the analysis of literature citing rotifers in salt waters, uncovers an unexpected rotifer fauna: the apparent richness of the group in thalassic environments is worthy of being addressed by further investigations, as many species have been reported only by their description, suggesting either considerable endemism or taxonomic errors.

The sub-structure of Atlantic cod (Gadus morhua) stocks in the North Sea has important consequences for fisheries management as the Common Fisheries Policy moves towards a more regional approach. We investigated the movements, distribution and behaviour of cod in the southern North Sea (ICES IVc) and English Channel (ICES VIId) by re-analysing historic data from conventional tagging experiments, and by conducting new experiments with electronic tags. Cod tagged and released in IVc showed a northwards shift in distribution during the feeding season consistent with a homing migration away from spawning grounds along the coasts of the UK and the Netherlands. In contrast, cod tagged and released in VIId did not exhibit a consistent pattern of seasonal movement. Many cod released in VIId were subsequently recaptured close to their release position, although some moved out of the Channel and into the southern North Sea. Overlap between the recapture areas of cod released in the different management areas was no more than 25% in either the spawning or feeding season. Behavioural data from electronic tags suggest that cod in IVc make use of tidal streams to migrate northwards and eastwards in spring, whereas selective tidal stream transport was rarely exhibited by cod tagged and released in VIId. Overall, the evidence suggests that there are behavioural differences between cod in IVc and VIId that limit the mixing of cod from these two areas during the feeding and spawning seasons.

Sea water is a complex solution in which the principal ions are sodium, potassium, calcium, magnesium, chloride and sulphate. The vapour pressure (V.P.) of such a solution can be calculated approximately by making the assumption that each salt contributes to the vapour pressure lowering in amount proportional to its concentration, but such a calculation would ignore the interactions between the various ions. The theory of these interactions has been worked out only for very dilute solutions and it is, therefore, better to rely on direct experimental determinations. Measurements have now been made by the isopiestic vapour-pressure method (Robinson & Sinclair, 1934), in which samples of sea water are equilibrated with sodium chloride solutions until they have the same vapour pressure. The results are expressed in terms of chlorinities of sea water and molalities (moles per kilogram of H2O) of sodium chloride solution which have the same vapour pressure. It is hoped that the results will be of use to physiologists who have occasion to make up salt solutions equivalent to sea water.

The chitin from pogonophore tubes is shown to be essentially the same as that from the pen of the squid Loligo and is classified as β-chitin (as are the known chitins in annelids). However, certain important differences in detail are seen when comparing X-ray diffraction photographs and infra-red absorption spectra of the chitin from the two sources. These matters are of interest in defining the systematic position of the Pogonophora as well as in reaching an understanding of the functions of the protective tube.

Six species of algae, Chlorella marina Butcher, Dunaliella tertiolecta Butcher, Isochrysis galbana Parke, Monochrysis lutheri Droop, Phaeodactylum tricornutum Bohlin and Hemiselmis virescens Droop were fed to oyster larvae in bacteria-free culture. In addition, cultures of Chlorella stigmatophora Butcher, Isochrysis galbana and Phaeodactylum tricornutum containing bacteria were also used. Cultures of galbana containing bacteria were used as controls in all series of experiments. In each series various densities of food, expressed both as cell numbers and as packed cell volume, were fed to the larvae of Ostrea edulis L. for 22–46 h and the change in the mean size of the larval population was used as the index of the value of the food.

The experiments with Chlorella confirmed previous work that organisms of this genus have little value as food for larvae. With Dunaliella and Phaeodactylum growth was better at low food densities with some (but not all) batches of larvae compared with Isochrysis. The comparison of cultures of Isochrysis and Phaeodactylum with and without bacteria showed no consistent improved growth with either food. Monochrysis had about the same food value as Isochrysis. With Hemiselmis some growth was obtained but not as much as with Isochrysis.

This study was undertaken to increase our very incomplete knowledge of the annual cycle inascidians.

Berrill (1950) states that ‘the age of ascidians, with one exception, is practically impossible to estimate, unless a certain inhabited area is followed closely through seasons and years’. In the present work the method has been to follow certain aspects of the ascidian population of a chosen area for a period of nearly two years. The area was the Old Dock in Ardrossan Harbour, Ayrshire, and the ascidian population contained four species: Diplosoma listerianum (Milne Edwards), Ciona intestinalis (Linnacus), Ascidiella aspersa (Müller) and Botryllus schlosseri (Pallas). Diplosoma belongs to the order Enterogona, suborder Aplousobranchiata; Ciona and Ascidiella to the order Enterogona, suborder Phlebobranchiata; and Botryllus to the order Pleurogona, suborder Stolidobranchiata. Thus each of the three main suborders is represented, and the four ascidians studied are amongst the commonest British species.

Nutritionally, there are three basic types of Dinophyceae: (1) free-living photosynthetic autotrophs; (2) parasitic heterotrophs living on or in other organanisms and (3) free-living phagocytic or chemosynthetic heterotrophs. Representatives of the first type, the free-living photosynthetic autotrophic species, have been extensively investigated at the fine-structural level (for a review see Dodge, 1971). There are fewer species of the second type, the parasitic Dinophyceae, but many of these have been investigated in the electron microscope (Cachon & Cachon, 1966, 1970, 1971a, b; Cachon et al. 1968; Soyer, 1969 c; Manier, Fize & Grizel, 1971; Siebert & West, 1974). The third type, the free-living heterotrophic Dinophyceae, probably comprises the greatest number of species in the class; as Kofoid & Swezy (1921) state ‘One cannot work with the marine unarmored Dinoflagellata for even a short time without being struck by the fact that the majority of the individuals observed show evidence of holozoic nutrition and that the number actually containing chromatophores is relatively small throughout the entire Dinoflagella’. While the free-living heterotrophic Dinophyceae comprise the largest proportion of the class they have been, by far, the most poorly studied at the fine structural level. Investigations on these organisms have been limited to a comprehensive study of Oxyrrhis marina (Dodge & Crawford, 1971a, b, 1974) plus studies on specific parts of Cryptothecodinium cohnii (Kubai & Ris, 1969; Pokorny & Gold, 1973) and Noctiluca miliaris (Afzelius, 1963; Soyer, 1968, 1969a, b; Zingmark, 1970).

At least a quarter of the world's cetaceans were recently confirmed as endangered and the situation may be worse as the status of many others remains unclear. Climate change is affecting the oceans and a number of studies have recently highlighted its potential impact on cetacean species - for example, there are important linkages between sea ice and krill, the primary prey for baleen whales in Antarctica. This paper provides a synthesis of new information available on this theme and considers its implications for the future conservation and management of cetacean populations and species.

The more mobile (or otherwise adaptable) cetaceans may be able to respond to climate related changes, although the extent of this adaptability is largely unknown. However, there is broad agreement that certain species and populations are likely to be especially vulnerable to climate related changes, including those with a limited habitat range, or those for which sea ice provides an important habitat for the cetacean population and/or that of their prey. International conservation bodies, such as the Convention for Migratory Species and the International Whaling Commission, are striving to address these issues. The challenges presented by climate change require an innovative, large scale, long term and multinational response from scientists, conservation managers and decision makers. This response that should encompass a precautionary approach, including addressing the detrimental effects of other factors negatively impacting populations and species.