Miniature acoustic transponders wrapped in bait were deployed on the sea floor in the continental rise and slope regions of the Porcupine Seabight during August 1992. These were ingested by Centroscymnus coelolepis (Chondrichthyes, Selachii) at 1517–1650 m depth, Antimora rostrata (Osteichthyes, Moridae) at 2020–2501 m depth, and Coryphaenoides (Nematonurus) armatus (Osteichthyes, Macrouridae) at 2501–4050 m depth. Fish with baits in their stomachs were tracked using a scanning sonar deployed on the sea floor. All fish had moved out of range of the sonar (500 m) within 3–9 h of the bait reaching the sea floor, indicating no site fidelity. Swimming speed of C. (N.) armatus increased with depth from 0056 m s-1 at 2500 m to 0·109 m s-1 at 4000 m. This is partially explained by a bigger-deeper trend in fish size.

The escal light gland of three different-sized specimens of the deep-sea anglerfish Haplophryne mollis (family Linophrynidae) has been examined by light and electron microscopy. The light gland has a central cavity, with diverging branched ducts which ramify into numerous tightly-packed radial tubules. In the two largest specimens all glandular lumina contain symbiotic bacteria. Except for a thin-walled part of the typical radiating tubules, the epithelial walls of the light gland are of a uniform structure, consisting of flattened basal cells, situated next to the basal lamina, and tall cells extending to the lumen.

In the smallest specimen examined the various parts of the light gland were not fully differentiated and only a very few symbiotic bacteria were present; its glandular epithelium differed from that of the two larger specimens by containing many goblet cells, the secretion of which may be important for the initial establishment of the right strain of symbiotic bacteria

Observations on the luminescence of live specimens have shown that the light emission can be rapidly modulated from within the esca. The in vivo flash kinetics are considerably slower than those of Dolopichthys longicornis, but similar to those of both the caruncle exudate of Ceratias holboelli and in vitro anglerfish bacterial luciferase.

Marine organisms have long provided ideal systems for the study of development. The reasons for this are essentially twofold. Firstly, gametes, zygotes and embryos of many species are relatively accessible, facilitating observation and experimental manipulation. Secondly, the exceptional diversity to be found in the sea allows wide ranging comparative and evolutionary studies. The aim of this meeting was to highlight significant advances in developmental biology research using marine organisms and to bring together workers from a variety of disciplines to encourage cross-fertilization of ideas and comparisons between different systems. Particular attention was paid to new approaches for solving fundamental problems at different levels of complexity and organization. The meeting was organized such that parallel developmental processes in different systems, both animal and plant, could be compared. Sessions covered egg activation/cell cycle control; polarization/early development; embryogenesis/larval development; and the interaction between development and environment. Examples were chosen from a wide range of organisms, including molluscs, echinoderms, asddians, echiuran and polychaete worms, ctenophores, copepods, amphioxus, fish and algae (Brownlee, 1993).

Soft tissue δ13C values were determined in vestimentiferan tube worms, alvinellid polychaetes and molluscs from Axial Seamount and Middle Valley, North-east Pacific. Inorganic carbon in mollusc shells and water samples was also analysed. In the vestimentiferan, Ridgeia piscesae, which lives in symbiosis with sulphur-oxidizing chemolithoautotrophic bacteria, tissue samples from the Axial vents showed δ13C values from −11 to −16‰, whereas at Middle Valley, where venting occurs through sediments, the δ13C ranged from −16 to −26‰. The tissues of an associated polychaete, Paralvinella palmiformis, which feeds on free-living bacteria, had δ13C values in the range −21 to −26‰. The bivalve Calyptogena from Middle Valley was more depleted than Ridgeia and Paralvinella, −37‰, closer to the ratios found in chemolithoautotrophic symbioses in non-vent habitats. Considerable, but variable, depletion (−23 to −42‰) was found in small gastropods. Mollusc shells and diluted vent water differed little in δ13C compared to inorganic carbon in ambient deep sea-water.

Demersal fishes on the continental rise and slope were sampled by trawl, baited trap and a baited camera. Seventy-one different species were trawled, but only 18 species approached baits. At rise soundings (4100 m to 2250 m) Coryphaenoides (Nematonurus) armatus was dominant at baits and comprised 41·5% of the trawl catch. On the slope (<2250 m) Synaphobranchus kaupi was dominant at baits and comprised 32·7% of the trawl catch. At 1500–2501 m Antimora rostrata competed at baits and comprised 5–10% of trawl catches. At 1500–1650 m Centroscymnus coelolepis also consumed baits but was not captured by trawl. For C. (N.) armatus abundance was proportional to tarr2 (where tarr= arrival time), demonstrating that arrival time of the first fish at baits provides an estimate of population density. Maximum estimated abundance at 2897 m was 877 km-2, more than five times the abundance on the abyssal plain. Halosauropsis macrochir, Lepidion eques, Coryphaenoides guentheri, Gadiculus argenteus and Coryphaenoides rupestris were important in trawl samples but absent or rare at baits.

Through SEM observations a probable sense organ located at the base of the ventral side of each dorsal cirrus in some eunicid polychaetes is described. This organ is externally characterized by numerous long ciliary projections. Similar structures are also found on corresponding positions in species belonging to other family groups in the Order Eunicida but in the Order Phyllodocida were found only in Aglaophamus sp. This species also has a similar structure, with ciliary projections, at the ventral base of each dorsal cirrus. However, the situation is quite different from any Eunicida species in that numerous bundles of ciliary projections are also scattered on the lateral sides of the body. Although the function of the ciliated organ of eunicids still remains unknown, a brief TEM observation of this organ on Marphysa sanguinea clearly shows that this organ is a sensory receptor and seems to suggest that it serves as a chemoreceptor rather than a mechanoreceptor.

It is generally agreed that fertilization in deuterostomes is accompanied by a large intracellular calcium wave that triggers the onset of development, but we still do not know exactly how the calcium wave is generated. The question has two parts: how does interaction of sperm and egg initiate the calcium wave, and how does the calcium wave spread across the cell? Two provisional answers are available to the first part of the question, one involving receptor-G-protein interactions of the sort that mediate trans-membrane signal transduction in somatic cells, the other injection of an activating messenger when sperm and egg fuse. Both these ideas are being actively pursued; the dialectic is productive, albeit no synthesis is in sight. We discuss their strengths and weaknesses. The second part of the question can now be much more precisely formulated: thanks to the recent flush of interest in calcium waves in somatic cells, new ideas and new experimental tools are available. The work on somatic cells repays a debt to eggs, where the basic properties of calcium waves were first set out, ten years before they turned up in somatic cells.

The Raman spectrum of a cell homogenate obtained from the unfractioned blood cells of Ascidia gemmata was recorded in an effort to determine the ratio of the level of sulphate to that of vanadium in the blood cells. The ratio obtained was 1·47, which is close to 1·5, the value predicted if sulphate ions are present as the counter ions of V3+ ions. We found evidence that an aliphatic sulphonic acid is present in the blood cells, namely, the Raman spectrum of the cell homogenate included a band at 1044 cm−1, which corresponds to the symmetrical stretching vibration of the SO3− group of the anion of cysteic acid.

Light and electron microscopical studies were carried out in order to characterize the blood cells of the bivalve mollusc, Scapharca inaequivalvis (Bruguière). Cytochemical techniques were also used to investigate peroxidase, phenol oxidase and lysosomal enzyme activity in the cells. Four types of blood cell were found: the more numerous erythrocytes and three populations of white blood cells. The red blood cells were found to be nucleated and contained dense cytoplasmic granules and various organelles; a well-developed Golgi apparatus, rough endoplasmic reticulum, variable numbers of mitochondria and fine cytoplasmic microtubules were observed. The white blood cells were generally smaller and less frequent. The type 1 cells possessed variable numbers of acidophilic, cytoplasmic granules and showed a high degree of vacuolation. The highly granular cells showed more extensive pseudopodia, perhaps indicative of intense phagocytic activity. The type 2 cells were basophilic and possessed few or no cytoplasmic granules. The type 3 cells were infrequently seen; they were relatively large and packed with large, dense, acidophilic, membrane-bound granules. Peroxidase and arylsulphatase activity was found to be present in the type 1 and 2 white blood cells and in the cytoplasmic granules of the erythrocytes. No phenol oxidase activity was detected.

In the undisturbed sea urchin embryo, cleavage of the blastomeres is invariant and gives rise to five polyclonal territories that are each defined by the larval structures to which they give rise, and by unique programmes of gene expression. These territories are the aboral ectoderm, the oral ectoderm, the vegetal plate, the skeletogenic mesenchyme, and the small micromeres. Structural gene markers for four of these territories (all except the small micromeres, which participate in later development) have been cloned and characterized, and the regulatory domains of several of these genes have been mapped to the level of specific protein-binding sites.

The analysis of 35 bottom trawls taken on the slope in the Catalan Sea (western Mediterranean) has shown the existence of two different demersal fish assemblages occurring on the upper (350–650 m) and middle (1150–1300 m) slope. The middle slope assemblage is characterized by much higher values in some ecological parameters such biomass and mean fish weight, resulting from the dominance of middle to large size species (e.g. Alepocephalus rostratus, Trachyrhynchus trachyrhynchus, Mora mom). On the upper slope two different stations were considered, one inside and the other outside a submarine canyon. Only slight differences were found in species composition, and hence sample and species were not clearly separated by a correspondence analysis. However, some interesting ecological differences exist between these two stations. Much higher values in abundance and biomass inside the canyon were indicative of higher food availability there. Moreover, a drop in mean fish weight was also noted inside the canyon. The analysis of size distributions in the commonest species along the upper slope showed that the submarine canyon acts as a recruiting ground for some of them.

Gill number 8 of intermoult male Carcinus maenas (L.) (Decapoda: Brachyura) was used to study the morphological variation and distribution of the major gill cells. Three gill regions (proximal, mid and distal) were sectioned and examined by light and transmission electron microscopy. The ultrastructure of the three epithelial cell types (striated, chief and pillar) was similar to previously published descriptions, but some variations in cell form and distribution were observed. In all gill regions, striated and chief cells were larger towards the lamellar raphe than near the marginal canal. In the proximal gill region, the epithelium consisted almost exclusively of striated cells, implying an osmotic/ionic role for this region. In the mid gill region, the epithelium comprised a mixture of chief and striated cells. In the distal region, chief cells predominated, implying a respiratory role for this region. Pillar cells exhibited no clear distributional pattern within the gill and, although their shape varied with position, their involvement in ionic regulation, osmoregulation, respiration, structural support or the flow of haemolymph through the gill is not clearly defined. Nephrocytes, thought to be involved in gill defence mechanisms, occurred in the haemolymph space or attached to the intralamellar septum and showed no structural variability. Glycocytes were always associated with the intralamellar septum, implying that there are specific gill regions for glycogen storage. Haemocytes showed some structural variation but there was no obvious correlation with gill region; small-granule haemocytes were the most common haemocyte type in the gill.

A Galway Bay population of the dragonet Callionymus lyra (L.) was investigated between March 1978 and November 1979. Monthly collections were made on board commercial fishing vessels. A total of 3302 fish was examined. The male to female sex ratio in the catch was 1·14:1 and it departed significantly from a 1:1 ratio. Males grew significantly faster than females, when measured by length and by weight, and attained a greater maximum length, but females had a longer life span. Females were significantly heavier than males for any body length. The spawning season was protracted, lasting from January to August and peaking during February-April. Callionymus lyra is a carnivore, feeding mainly on polychaetes and crustaceans, but molluscs and echinoderms were also eaten in abundance. A yearly cycle in feeding intensity was observed, showing reduced feeding during the colder months. The feeding index expressed as gut weight / body weight was significantly higher for females.

The extracellular matrix of the sea urchin involves a protein with a molecular weight of 180 kDa (sea urchin fibronectin), which corresponds to mammalian fibronectin, and a nectin specific to Echinoidea with a molecular weight of 105–115 kDa (sea urchin nectin). Sea urchin fibronectin and sea urchin nectin have cell adhesion protein properties. They are, however, different from each other in biochemical properties, biological functions and intraembryonic distribution. Sea urchin fibronectin isolated from the sea urchin ovary accelerates scattering of micromere-derived cells and promotes spicule formation of micromeres in vitro. Sea urchin nectins identified so far in Paracentrotus lividus (Lamarck), Temnopleurus hardwicki (Gray) and Pseudocentrotus depressus (A. Agassiz) are presumably homologous molecules displayed in different species. They seem to be secreted into the hyaline layer as its constituents, and to play some role in morphogenesis of the embryo.

The membranous lobe of Thenus orientalis (Lund) is a broad fleshy protuberance arising midventrally from the sternal skeleton between the second maxillipeds. Its position, morphology and structure are described and its association with the metastome of other crustaceans discussed. Several roles during ingestion can be postulated. The lobe extends anteriorly towards the mandibles and forms the roof of the preoral cavity and posterior boundary of the mouth. It has a flattened strengthening rod extending the width of the aboral surface, which is covered by three types of anteriorly-directed annulate setae and densely arranged clusters of microscales and microspines. Histologically it is characterized by large amounts of longitudinal and circular striated muscle and tegumental glands beneath the oral surface. These glands secrete sulphated acidic mucopolysaccharides which lubricate food during ingestion. Spherical cells are dispersed throughout the connective tissue beneath the aboral surface. These are characterized by a granular homogeneous cytoplasm, a peripheral cell nucleus and few organelles. Their contents stain positively for protein and neutral mucopolysaccharides and their role is most likely storage of these compounds, although the significance of this is not known. During ingestion, food is passed over the lobe surface and its anterior lip retracts ventro-posteriorly, dilating the preoral cavity to allow quick and efficient swallowing of large food items.

The respiration rates of five genera of benthic Foraminifera were determined by Cartesian diver microrespirometry. Across all genera studied, the rate averaged 11·3×10−3 μl O2 individual−1 h−1 at 10°C. Estimates of foraminiferal mean biovolumes ranged from 0·66 to 6·54×106μm3, giving an overall mean volume-specific respiration rate of 7·36 × 10−9 μl O2 h−1 μm−3. For non-symbiont-bearing Foraminifera, in general, volume-specific rates (log μl O2 h−1 μm3) are best described by the equation, −0·98 × (log cell biovolume, μm3)−2·01. The respiration results show that these benthic Foraminifera respire some ten times more rapidly than naked amoebae of equivalent size. The combination of high respiratory rates and the often large standing stocks of Foraminifera encountered, suggests that these organisms may contribute significantly to total microbial benthic respiration.

Ascidian development is reviewed and a model is presented for specification of the larval body plan and cell fate during embryogenesis. The model involves the combined activity of determinants inherited from the egg and inductive cell interactions in the embryo. It is suggested that there are four determinant systems in the egg which are segregated to different blastomeres during cleavage. The ectodermal, endodermal, and muscle determinants specify cell fate autonomously, while the axial determinants initiate cell-shape changes at gastrulation and generate a cascade of inductive activities establishing the larval body plan. In the proposed signalling cascade, the endoderm induces notochord by generating a planar inductive signal late during the cleavage phase, and the notochord cells in turn induce the nervous system by generating a vertical inductive signal in the overlying ectoderm during gastrulation. Ultraviolet (UV) irradiation experiments are described which suggest that axial and muscle determinants exhibit UV-sensitive components resembling nucleic acids and proteins, respectively. The model is evaluated in terms of developmental changes during the evolutionary transition from indirect to direct development. This transition can be explained according to the model by loss or inactivation of the muscle determinants and modification of the inductive activities generated by the axial determinants. These changes are supported by recent studies of embryogenesis in direct-developing ascidians.

Atlantic salmon smolts were sampled from the intake screens of the Oldbury power station in the inner Severn Estuary at weekly intervals between July 1972 and June 1977. These catches, and those taken over nearly three years from the nearby Berkeley power station, demonstrated that the abundance of smolts in the estuary peaked in autumn (October) and, to a far greater extent, in spring (April and May). However, small numbers of smolts were occasionally found in all other months of the year except July. Standard length-frequency distributions of smolts remained unimodal throughout the year. Lengths ranged from 76 to 187 mm, mean 130·2 ±1·87 mm (95% CL), and wet weights ranged from 5·4 to 68·0 g, mean 26·9 ±1·17 g. The mean monthly standard length of smolts increased slightly between the autumn of one year and the spring/early summer of the next year, suggesting that, on average, the former were six months younger than the latter. The condition factor was significantly greater in autumn (1·40) than in spring (1·23). It is estimated that the total number of salmon smolts entrained annually on the screens at Oldbury during the five years ranged from 92 to 791, with a mean of 405. Total estimated numbers at Berkeley ranged from 196 to 788 per annum. The numbers at Oldbury are lower than those estimated for the downstream migrants of the Twaite shad, another anadromous species, and far lower than those of the most abundant of the marine fish species that use the Severn Estuary as a nursery area.

The common sandhopper of European shores, Talitrus saltator (Montagu, 1808) (Crustacea: Amphipoda) remains inactive in high shore burrows for much of the winter in more northern latitudes. In the laboratory exposure to low temperature (2 or 3°C) was accompanied by the onset of inactivity, a precipitous decrease in oxygen uptake and a marked increase in the concentrations of the major ions in the haemolymph. The increase in the concentration of Mg2+ in the haemolymph was particularly pronounced. The possibility that Mg2+ ions are implicated in bringing about a reduction in activity and oxygen uptake is discussed.

The functional morphology of the buccal mass of 23 species of cephalopod (Octopoda, 4 species; Teuthoidea, 17; Sepioidea, 2) was investigated by gross dissection, histology and observations on fresh preparations. Cephalopod beaks lack a joint or articulation point. The jaws slide and rotate around an area rather than a fixed point. During closing the superior mandibular muscle (SMM) provides the force of a bite and the largest movement vector, whilst the inferior mandibular muscle (IMM) acts to retract the upper beak, causing shearing action. Dorsal portions of the lateral mandibular muscles (LMM) flex the upper beak walls outwards, probably to accommodate the backwards sweep of the radula and buccal palps during closing. To open the beaks, the ventral portions of the lateral mandibular muscles pull the rear lateral walls of the two beaks towards each other, moving the lower beak back relative to the upper.