Prokaryote organisms, with characteristics of Gram-negative bacteria, occur intracellularly in Pogonophora, as described here for seven small species. The tissue containing the bacteria lies between the two longitudinal blood vessels in the posterior part of the trunk and has a special blood supply. This tissue is probably homologous with the so-called trophosome tissue of the much larger vestimentiferan pogonophores, which also contains bacteria, and the term can be applied to all pogonophores. The presence of such bacteria-containing trophosome tissue may be a characteristic of the phylum. In both large and small species examined the bacteria appear to be chemoautotrophs and probably assist the nutrition and/or metabolism of their hosts. It is not yet certain if the bacterium-containing cells do originate from mesoderm or endoderm, but, if the latter, then the trophosome represents the remains of the missing gut. The trophosome tissue situated internally, and transfer of bacteria must take place early in the life history, in the egg or embryo.

The ultrastructural organization of various metal-containing cells of Littorina littorea is described. These cells occur in the connective tissue, digestive gland, kidney, stomachand ctenidia. Specimens were compared from animals collected from clean and metal-polluted sites and it was shown that the majority of the metals were bound to intracellular ligands. These are usually compartmentalized within membrane-delineated structures.

The basophil cells and connective tissue calcium cells appear to contain oxygen donor ligands which mainly bind class A metals (e.g. Ca, Mg, K, Mn). The pore cells and ctenidium contain sulphur donor ligands which mainly bind copper. Ligands of unknown composition occur in the nephrocytes and stomach epithelial cells. The ligands in the basophil cells and the nephrocytes appear to bind a wide range of metals and may therefore serve a detoxification function. Ligands in the connective tissue calcium cells and pore cells are very specific in their binding characteristics, and this presumably reflects some particular metabolic pathway within these cells. Ligands associated with the stomach and ctenidial epithelia appear to be responsible for preventing the penetration of metals through these layers.

The effects of ligand specificity, induction and turnover rates are discussed in relation to the use of L. littorea as a monitoring system for metal pollution.

Introduction

The use of biological organisms to monitor the levels of pollutant metals in the environment has attracted extensive interest in recent years (Phillips, 1980). In the most arbitrary use of this procedure, the animal is simply regarded as a biological sink' which traps and accumulates the pollutants which gain access across its epithelial layers. The net result of the retention or excretion of these captured metals is represented by the final body load that is then related to the environmental levels of the metal.

International efforts are currently being made to establish networks of marine protected areas (MPAs) for the purposes of conservation of marine biodiversity. One of the primary objectives of MPA networks is to achieve representation of all marine biological diversity. Since we do not know the extent of biological diversity nor its distribution and function, we use surrogates to represent biological diversity. At a broad scale, measures of the physical environment are used, however at a fine scale biological assemblages have been shown to provide better representation of known biological diversity. While there are well known descriptions of assemblages for shallow water environments, few such descriptions of deep-sea benthic assemblages have been attempted. This paper provides descriptions of deep-sea epibenthic megafaunal assemblages based on a broad-scale video and stills image survey of the upper bathyal (200–1000 m) regions of the Rockall Trough and eastern Faroe–Shetland Channel. One thousand nine hundred and eighty-seven images were analysed from 139 video transects sampled from Dangaard and Explorer Canyons, Rosemary Bank Seamount, Hatton Bank, Wyville-Thomson Ridge, and the continental slope west and north-west of Shetland. Quantitative data obtained were analysed using cluster analysis and SIMPER analysis in Primer V.6 to identify benthic assemblages and their characterizing species. Thirty-one epibenthic megafaunal assemblages are defined by their characterizing species, and their distribution in terms of site, depth, temperature and substratum type. These 31 ‘biotopes’ provide consistent units for use in biological mapping efforts and assessments of representativeness in MPA network design. To facilitate the incorporation of these biotopes into existing deep-sea classification systems the biotopes have been assigned to broad substratum types. This is consistent with the use of substratum as a surrogate in many existing systems.

The harbour porpoise is the only resident cetacean species in the German Baltic Sea. Within the last several decades this harbour porpoise stock declined drastically, causing deep concern about its status. Plans of the German government for proposing Marine Protected Areas (MPAs) to implement Natura 2000 and for assessing the impact of offshore windmill constructions on the marine environment led to an increased research effort on the harbour porpoise in German waters. For the first time, long-term passive acoustic monitoring has been conducted in the German Baltic Sea from the Kiel Bight to the Pomeranian Bay from August 2002 to December 2005. Porpoise detectors (T-PODs) have been installed five to seven metres below the water surface at up to 42 measuring positions throughout the investigated area, registering the exact times of echolocation signals of passing harbour porpoises. The proportion of monitored days with porpoise detection in each quarter of the years has been analysed. A correlation of the results with the longitude of the measuring position revealed a significant decrease from west to east in the percentage of days with porpoise detections. Comparison of data gathered in the first quarters with the third quarters of the monitoring years displayed a seasonal variation with fewer days of porpoise detections in winter time than in summer time. Nevertheless, harbour porpoises have been detected year-round at most of the measuring positions in the German Baltic Sea. The present study clearly indicates a regular use of the German Baltic Sea by harbour porpoises with a geographical and seasonal variation in the usage of the German Baltic Sea. The larger numbers of harbour porpoise detections in spring to autumn compared with winter suggests that the German Baltic Sea is an important breeding and mating area for these animals.

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.

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.

A high concentration of certain planktonic animals was found in a frontal region in the English Channel. Temperature, salinity and current measurements and direct visual observations (underwater) describe the nature of the front. It is shown that water depth, season, strong tidal mixing and residence time are important factors leading to the formation and maintenance of a turbulent convergent tidal front.

Analyses of the jaws of nereid polychaetes have shown zinc to be a major inorganic component amounting to between 0·5 and 2·4% of the dry weight and accounting for up to 40% of the total body burden of zinc. In Nereis diversicolor, zinc concentrations in the jaws are not related to those of the habitat sediments. A high zinc content appears to be a structural characteristic of the nereid jaw.

Large, common, tough, the lugworm is an outstandingly good object for anatomical and physiological work. Its mode of life has not yet been clearly worked out, and one must know how an animal lives if one wishes to understand its structural and functional peculiarities. Burrowing as it does in muddy sand, the lugworm cannot be watched under natural conditions (except on the rare-occasions when itshows itself on the surface). Existing accounts of its behaviour inthe field are therefore practically confined to the form of the burrow which it excavates. The present paper attempts to synthesize, partly from field observations and partly from laboratory studies ofthe worm's activities, a coherent picture of its daily life.

Adult female Calanus helgolandicus Claus immersed for 24 h in sea-water solutions of [1-14C]naphthalene accumulated a detectable quantity (3.6 pg/animal) from concentrations as low as 0.10 μg/1.

Feeding experiments using barnacle nauplii or diatoms as foods showed that the dietary route of entry was more important quantitatively than direct uptake from solution in that in order to ensure that the same quantity of radioactivity in the animals was attained by the two routes the level of hydrocarbon in solution had always to be far greater than that present as paniculate food. Relevant to these observations was the further finding that after naphthalene had been accumulated directly from solution in sea water depuration was rapid and only a small fraction, less than 5%, of the original radioactivity could be detected after 10 days: by contrast, when the hydrocarbon was taken up by way of the food depuration was much slower, so that at the end of 10 days about a third of the original level of radioactivity still remained in the animals. Short-term experiments in which Calanus were fed on labelled diets for 24 h under bacteria-free conditions showed that at the end of this period over 90% of the radioactivity in the animals was present as unchanged naphthalene. However, more than two thirds of that released by the animals was in some form other than the hydrocarbon, a finding consistent with the view that Calanus is able to metabolize it.

During his studies on the Cirripedia Darwin (1854) gave much attention to the Chthamalidae, and his views of the species remained unchallenged for many years. Darwin's attitude to speciation appears to have been coloured by his concurrently developing theories of natural selection, and he was especially interested in the existence of wide variation within species. Thus Chthamalus stellatus as described by Darwin consisted of a number of races or varieties, and was of almost worldwide distribution (‘southern England, Ireland, Isle of Man, Mediterranean, Madeira, Cape Verde Is., southern United States, West Indies, Brazil, Rio Plata, Red Sea, Philippines, China, Gulf of Korea, Oregon or N. California’). This distribution has been considerably narrowed in the last 60 years, and recent investigators have raised varieties to specific rank, or described new species and subspecies. In North California and Oregon we now have the full species C. dalli (Pilsbry, 1916); along the eastern coast of U.S.A. we now have C.fragilis (Pilsbry, 1916); in the Caribbean and along the east coast of South America we have C. angustitergum and C. bisinuatus (Pilsbry, 1916; Ross, 1969; Southward, 1975); for the Indopacific region there are now the species C. challengeri and C. malayensis (Hoek, 1883; Pilsbry, 1916); and in the Mediterranean, C. depressus (Poli), which was reduced by Darwin to a variety of C. stellatus, has been raised again to specific rank (Barnes, 1956; Utinomi, 1959; Southward, 1964; Klepal & Barnes, 1975) and is now assigned to the genus Euraphia (Newman & Ross, 1976). Thus except for a few dubious records what remains of Darwin's C. stellatus is confined to Europe, N. Africa and W. Africa (Southward, 1964; Stubbings, 1967). Nevertheless, even such a reduced distribution encompasses several distinct climatic zones, and seems more extensive than the individual ranges of the three species (C. dalli, C. fissus and C. panamensis) found in comparable climatic regions of the N.E. Pacific.

Salinity is a major limiting factor in littoral and estuarine environments and the salinity encountered in such habitats fluctuates with tide, season and weather. Despite this variable situation, most investigations of salinity tolerance and osmoregulation have involved laboratory experiments at steady salinities. The literature devoted to such investigations is extensive, and has been reviewed on several occasions, notably by Krogh (1939), Potts & Parry (1964) and Kinne (1971).

The quantum yield and photosynthetic parameters of phytoplankton and sea ice microalgal communities were assessed from the Arctic Ocean and fjords of northern Svalbard. The phytoplankton community in Fram Strait was dominated by Phaeocystis while on Norskebanken it was dominated by diatoms. The quantum yield showed maximum values of 0·64 at 20–40 m below the surface and were consistent with nutrient replete waters elsewhere.

Sea ice infiltration communities were widespread and dominated by Phaeocystis. This is the first record of an Arctic infiltration ice community. Quantum yields were relatively low (0·247). Bottom ice communities, which were dominated by Nitzschia frigida, were extremely restricted and had moderate quantum yields (0·427). Communities growing on multiyear ice had quantum yields of only 0·126. All ice communities were well adapted to their light environment.

During 1934–5 I collected in Plymouth Sound and neighbouring waters seven species of the genus Corophium of which two were undescribed. I also collected one other species, and had sent to me two other species (one new) from other localities in South England. A list of these ten species, with the single other species known from Britain, is given in Appendix II, and their British distribution summarized.

In the course of identifying them I examined 23 of the 32 species of Corophium, and saw all the literature to which I could find references.

The chlorophycean alga, Brachiomonas submarina var. pulsifera Droop, was grown in two bacteria-free chemostats, differing only in the amount of light each received. Investigations were made into the changes in biochemical composition and calorific value of the cells when they were grown at different growth rates. This information was used to help to explain changes in the growth efficiency of the rotifer Brachionus plicatilis Miiller, grown in a bacteria-free chemostat which was linked to one of the algal chemostats, the algae being supplied as the source of food.

In continuation of my researches on the entozoa of British marine fishes I spent two months (August and September, 1909) at the Plymouth Marine Biological Station. By the courtesy of the Government Grant Committee of the Royal Society, a table was placed at my disposal and all expenses in connection with the investigation were defrayed.

Nitrogen excretion by Calanus finmarchicus (Gunnerus) and C. helgolandicus Claus collected at Millport and Plymouth has been measured under various experimental conditions.

Adult females feeding on Brachiomonas submarina, Cricosphaera elongata and Skeletonema costatum at cell concentrations corresponding to the mean annual level of particulate nitrogen in Plymouth Sound excrete 12·4, 9·0 and 6·4 μg N/mg dry body weight/day respectively. When the concentration of food is raised, as might occur during a spring outburst of phytoplankton, there is an increase in the quantity of nitrogen excreted. On the other hand, nitrogen excretion rapidly diminishes in the absence of food.

The view that bivalve molluscs are ideally adapted to fulfilling a mode of life in which the processes of feeding and digestion are continuous has long been accepted by most zoologists. An increasing amount of evidence, how ever, is being put forward to suggest that the opposite is true, that is, that bivalves are discontinuous in their feeding and digestive habits.

Hyperbenthos was sampled at six stations on the western slope of the Norwegian Trough. Four hauls, two day and two night replicates were taken at each station. The replicates were analyzed based on all sampled individuals of Mysidacea and Decapoda Natantia using Shannon diversity index, Spearman rank correlation, G-test, Bray-Curtis similarity index and Correspondence Analysis. The sampler provided samples of mysids and shrimps with an acceptable level of replicability based on number of individuals and diversity. In a cost-efficient context it is satisfactory to take only one sample at a station.

This review discusses the structure and operation of the fine mesh ‘mucous’ feeding filters of tunicates. The function of the endostyle in producing the feeding filter and the different ways in which the filter is deployed are also described.

The fine structure of the filter includes new data, and the ultrastructural dimensions of the filter mesh and filament thickness are tabulated for the different tunicate groups. Histochemical data suggest that a peptide core is surrounded by a mucopolysaccharide sheath, and endostyle gland cell histochemistry and ultrastructure indicates protein synthesis. The construction of the filter by the endostyle was first considered in ascidians, and has been updated by observations on the simpler endostyle in salps, where there is evidence that secretions of gland cells pass to the bases of a fence of cilia, there to fuse and pass off the ciliary tips as fine filaments composing the filter net. Although all filters that have been examined when deployed have a rectangular mesh, reasons are given for supposing that when formed in the endostyle they have a square mesh in which both longitudinal and transverse filaments are of similar thickness and that the transverse filaments are stretched as the filter is deployed, so becoming thinner.

Finally, some ecological consequences of the filter parameters in the different tunicate groups are considered.