Namanereids are an interesting group because of their success, remarkable amongst polychaetes, in colonizing freshwater habitats, particularly damp-terrestrial situations in tropical rainforests (see reviews by Feuerborn, 1932; Corrêa, 1948; Wesenberg-Lund, 1958; Hartman, 1959). Species assigned to the subfamily Namanereidinae Hartman, 1959 are now known from world-wide localities but there are few records from European waters.

This paper summarizes the available information on the distribution and biology of Maxmuelleria lankesteri. This large echiuran was described almost a century ago but its local abundance and potential importance as a bioturbator were recognized only recently. The species is widespread around the British and Irish coasts, most commonly in fine muds. A deep-burrowing, nocturnal deposit feeder, M. lankesteri is unlikely to be seen by divers, but its presence can be deduced from the form of ejecta mounds and proboscis tracks. The worms are very difficult to capture intact. Body size in a sample from Loch Sween, Argyll, was approximately normally distributed. Very small individuals are rarely found. Developing oocytes were found in the coelom over the spring and summer. Mature eggs accumulate in the gonoducts, with maximum loads found from October to December, possibly indicating a single annual spawning during the winter. Despite intensive examination of a large number of adult females, no dwarf males were found, leaving open the question of their existence. The large, yolky eggs indicate lecithotrophy or direct development. Larval stages have not been recognized. The apparent scarcity of developmental stages and of very small adults suggests that recruitment may be sparse and infrequent.

Scavenging amphipods were studied at three locations along the 20°W meridian in the north-eastern Atlantic using vertical arrays of baited traps. The sampling sites had several features in common. All amphipods captured belonged to the superfamily Lysianassoidea. Generally, highest densities of amphipods were found in the bottom traps. Abundances as well as species diversity were strongly reduced in traps exposed from 8–500 m above bottom. However, differences between stations occurred in standing stocks, decreasing from north to south, in the taxonomic composition of the bait-attending amphipods and in the vertical distribution and size structure of the giant amphipod Eurythenes giyllus.. Possible reasons for the differences between the locations are discussed and the establishment of at least two provinces in terms of bait-attending amphipods in the eastern North Atlantic is suggested.

The stomach contents of ten species of elasmobranch from the north-eastern Atlantic indicate that most are generalist predators, eating a variety of polychaetes, molluscs, crustaceans and teleosts. Two species, Mustelus asterias and Squatina scjuatina were found to be specialist feeders, consuming portunid crabs and pleuronectids, respectively. Measures for both dietary breadth and dietary overlap are given and the implications of elasmobranch predation on the prey communities and on commercial species are discussed.

A technique is described for the in vitro culture of the eggs and embryos of amphipod crustaceans. The technique was used, with mixed success, to culture the eggs of four species of amphipod (Gammarus duebeni, Orchestia gammarellus, Gammarus pulex and Echinogammarus pirloti) through to hatching. Eggs of the brackish water G. duebeni showed good hatching success in culture (70–75%) over a wide range of experimental salinities (75–1250 mOsm kg1). The eggs of O. gammarellus showed higher mortality rates in culture (compared with G. duebeni), especially in more dilute salinities (300 mOsm kg1) in which they swelled greatly prior to disintegration. Survival and true growth (as distinct from osmotic swelling) of O. gammarellus embryos in dilute salinities were significantly im-proved by introducing embryos into culture at a later stage of development. Antibiotic treatment had no demonstrable effect on embryo survival or growth. Whilst difficult to culture using this method, the eggs of the fresh water G. pulex showed best hatching success on a very dilute saline medium (~40 mOsm kg1). The results are discussed in relation to the development of embryonic osmoregulation, the implications for brood pouch function and the potential for female control of the embryonic environment, especially in semi-terrestrial species.

Ninety-six species (97, 677 individuals) were collected over the course of 6 h in five suprabenthic sledge hauls from a very dense Ampelisca fine sand community from the Bay of Morlaix (western English Channel). All the species migrated into the water column at night (98% of the specimens collected in the suprabenthos were found in the night hauls). The 23 most abundant species collected were classified into five groups based on their height within the water column, but two groups predominated: the upper suprabenthic species, abundant at 0–80–145 m above the sea-bed; and the lower suprabenthic species which were abundant only near the sea bottom (-0–1–0–75 m high). Three different patterns of nocturnal vertical migration were distinguished based on the timing of maximum swimming activity: at dusk; at the beginning of the night; or later in the night. Sexually dimorphic patterns of free-swimming behaviour was observed in Ampelisca and some other species of Amphipoda (Bathyporeia teniupes, Metaphoxusfultoni), and Cumacea (Bodotria pulchella, Pseudocuma longicornis), with many more males than females migrating into the water column at night. Finally, the density of suprabenthic crustaceans in nocturnal hauls was amongst the highest reported from infralittoral or circalittoral suprabenthic studies on other parts of the Atlantic Ocean sampled during spring.

The distribution of Dodecaceria in northern Europe was found for samples borrowed from museums and other collections. Dodecaceria fimbriata was present in the coastal waters of mainland Britain and the Continent from the English Channel northwards. Dodecaceria concharum was only found in British mainland coastal waters and on the French coast at the western end of the English Channel. It was absent where salinities were below ~34%0. The two species were sampled along the Lothian and Borders coasts and the numbers of D. concharum fell with decreasing salinity as the Firth of Forth was approached. Dodecaceria diceria was found for the first time in the North Sea at depths of 100–200 m. The benthic salinity here is ~35%0.

Morphometric data on bass, Dicentrarchus labrax L. (Pisces: Percoidei), sampled around the coasts of England and Wales between 1982 and 1990, have been analysed to elucidate seasonal patterns of feeding, body condition and gonad maturity. The somatic condition and fat reserves of bass in the Irish Sea and southern North Sea improved more rapidly during the spring and summer than in bass further to the south. In winter, however, fat reserves were higher and there was more food in the stomachs of bass caught in the western English Channel. The onset of maturity was related to fish length. Male bass became mature for the first time at 32–36 cm total length, but though many females showed signs of gonad growth at this size, no female <42 cm was found with mature (ripe or spent) gonads. Gonad development in adult bass of both sexes began in October and, from January until June, most males >36 cm had ripe testes. The period during which ripe eggs could be expressed from the ovaries of female bass was briefer, with spawning apparently peaking in April. It is concluded that the migration of adult bass to the north in spring and southwards and westwards in autumn has both growth and reproductive benefits related to sea temperature, and that the more limited movements of bass <42 cm, which remain in relatively cold, inshore waters in winter, results in an inhibition of gonad maturity in females.

Results of a comparative study on the distribution, growth and reproductive bionomics of two species of sand-dwelling oedicerotid amphipod, Pontocrates arenarius and P. Altamarinus are presented. Pontocrates arenarius is a littoral species with highest population densities between mean tide level (MTL) and low water springs (LWS) while P. altamarinus lives in the immediate sublittoral between LWS and -2 m Chart Datum. Both species are iteroparous, have female biased sex ratios, year-round breeding and life cycles largely based on two generations per year. The percentage of ovigerous females in the total population indicates breeding activity, and temporal changes in this percentage (arcsin transformed) have been tested for correlations against seasonal variation in five environmental factors (mean maximum weekly air temperature, mean minimum weekly air temperature, mean weekly sea temperature, day length, and mean weekly windspeed). Based on these analyses, differences in the timing of peak reproductive activity between these two species are interpreted as indicating the operation of different mortality agents, i.e. abiotic factors in the littoral P. arenarius and biotic effects (e.g. predation by fish) in P. altamarinus from the sublittoral.

The olfactory epithelium of developmental stages from yolk sac larvae to adults of plaice, Pleuronectes platessa L. (Pisces: Pleuronectidae) and Dover sole, Solea solea (L.) (Pisces: Soleidae) was examined using scanning electron microscopy (SEM). Two ciliated cell types and a microvillar cell are present in both species soon after hatching and persist into adulthood. In juveniles and adults of plaice, there were significantly higher densities of ciliated sensory cells in the eyed side of the fish than in the blind side over all regions of the olfactory lamellae. Densities of microvillar cells were an order of magnitude less than those of ciliated cells in regions on the wider part of the lamellae, with no significant difference between organs in most of these regions. On the narrow part of the lamellae, densities of microvillar cells were significantly higher than on the wide part, and significantly higher in the eyed side organ. In sole, ciliated cells were significantly more dense in the blind side organ in three of the four regions examined in this species. In contrast, microvillar cells showed a similar pattern to that in plaice, being significantly more dense in the eyed side organ in two of the four regions. Comparisons between the species showed significantly higher densities of both cell types in sole, microvillar cells being an order of magnitude denser in comparable regions on the lamellae. In addition, the total area of the olfactory lamellae is around three times greater in sole. These data point to a possible morphological basis for the enhanced olfactory capabilities of sole apparent from behavioural studies.

The occurrence of genetic differentiation among western Mediterranean Hediste diversicolor (Polychaeta: Nereididae) populations was assessed by allozyme electrophoresis on cellulose acetate. Seventeen loci were analysed in four populations. The level of the genetic variability was markedly low (mean HL range: 0.014–0.034), but comparable to that of other brackish water nereidids. The values of Nei genetic distance index (D) confirm the existence of genetic differentiation between the geographically isolated populations at Venice, Elba, Navicelli and Serchio D range: 0.128–0.356). However, the two samples from Serchio and Navicelli, ~15 km apart, were not genetically different (D=0·00005). The level of genetic differentiation in H. diversicolor populations followed the isolation-by-distance model. Reduced gene flow among H. diversicolor populations may be explained by its limited dispersal capacity and the eco-physiological barriers that occur between different brackish habitats.

Adult individuals of Talitrus saltator were tested for celestial orientation in a plexiglass bowl covered with colour filters of different wavelengths. Results show that T. saltator can recognize the sun and use it for orientation only at γ <450 nm. At γ >500 nm, the sight of the sun (and sky) only induces phototactic behaviour. It has also been confirmed that an important celestial orienting factor is perceived in the UV range. Variations in populations from diversely oriented coastlines are discussed. Preliminary results of electroretino-graphic responses indicate the presence of at least two visual pigments in the eye and a steep decrease in sensitivity for γ >500 nm.

Iorania concordia gen. nov., sp. nov. (Crustacea: Decapoda) belonging to the family Alvinocarididae is described from the Mid Atlantic Ridge, TAG location (26°09'N 44°50'W). The taxonomic position in the family and distinguishing characters (rostrum, armature of telson, form of first maxilliped) of the new genus are presented, and a possible evolutionary feeding hierarchy within the family is suggested. A key is given to the genera of the Alvinocarididae.

The effects of pentoses, hexoses and uronic acids upon the temporary adhesion of cypris larvae of five barnacle species from four families has been studied. A common, concentration dependent, inhibitory effect of D-glucose was observed for the five species, with maximum inhibition (to 60% of control levels) occurring at 10−8M glucose. Using Balanus perforatus larvae, glucose was shown to be acting at the antennular surface, most probably by interacting with polar groups associated with the temporary adhesive. The pentose, D-arabinose, was less active than glucose, reducing temporary adhesion to only ∞80% of control levels. D-glucuronic acid was more active, decreasing adhesion to 60% at 10−9M, whilst two other hexoses, D-mannose and D-galactose, showed similar activity to glucose. We suggest that hexoses interact with the same polar groups in the adhesive, glucuronic acid with the higher activity because of its more polar nature. The pentose possibly interacts with a different, less common, group. Our results suggest that the chemical identity of bacterial exopolymers, particularly in respect of their pentose: hexose and neutral suganuronic acid ratios, may be an important factor in determining the strength of temporary adhesion shown by barnacle cyprids towards bacterial films.

Dispersion of Lepeophtheirus salmonis Kreyer 1838 (Crustacea: Caligidae) larvae from a single cage and also from a farm system was investigated in Ardmore Bay, west coast of Ireland. Surface plankton tows were taken from within a cage and also at various distances from the farm. Highest densities of larvae (maximum, 66·1 m−3) were consistently recorded within the cage. Less than 10% of the larval density recorded inside the cage was found outside at any one time, indicating a high retention of larvae within the cage throughout the sampling period. This was due to a reduction of water movement inside the cage caused by the physical barrier of the net which was fouled during the sampling period. Highest densities of larvae were consistently found in samples taken at 10 m (maximum, 4·8 m−3) from the last cage on the farm in comparison to those taken further away from it (maximum, at 1 km; 0·4 m−3). Regression analysis of the data from each of the sampling dates showed a significant inverse relationship (P=0·001) between distance and larval numbers. The models produced suggest that few louse larvae would have been recovered in samples (i.e. 100 m plankton surface tows) taken more than 2 km from the last cage on the farm. Although the ratio of copepodids to nauplii increased with distance from the farm, the densities of the copepodids did not increase.

Angular sensitivity functions were determined electrophysiologically for retinula cells in Nephrops norvegicus and Munida rugosa. For such aquatic species it is shown that reliable measurements cannot be obtained unless the eyes are submerged. In both cases, for submerged eyes, there is a significant reduction in retinula cell acceptance angles with light adaptation. In N. norvegicus the change is from 11·3° dark adapted (DA) to 8·85° light adapted (LA). In M. rugosa there is a larger difference, 12·5° (DA)–6·58° (LA). The changes in acceptance angle with adaptational state can be attributed to differences in screening pigment position between light- and dark-adapted eyes. In N. norvegicus only the retinula cell proximal pigment is migratory. The small change in acceptance angle with adaptation is consistent with the fact that the eye uses superposition optics even when light-adapted.

Protellina ingolfi Stephensen, 1944 was first reported from the southern Norwegian Sea, collected during the Danish Ingolf Expedition in 1895–96. This species was described from what Stephensen presumed was a adult male specimen (Stephensen, 1944). Additional specimens collected during the joint Nordic BIOFAR (Biological Investigation of the Faroes) and BIOICE (Biological Investigation of Iceland) programmes differ from the original description by Stephensen. Male, female and juvenile males are described and illustrated, and any morphological difference between Stephensen's (1944) original description and current material are discussed.

Based on the bivalve fauna known from an extensively studied zone, along the infralittoral in the Patras Gulf, a biotope approach was attempted using numerical taxonomy methods. The efficiency of various combinations of similarity measures and clustering techniques is discussed for this type of data (single group – binary). Four main station groups were delimited which were further assigned to the biotopes of known Mediterranean biocoenoses. The four groups correspond to: (a) the biotope of the Posidonia beds (HP) and that of coarse sands and fine gravels under the influence of bottom currents (SGCF). The limits of these two biocoenoses are not clear-cut, (b) The biotope of the coastal detritic bottoms (DC) usually occurring in deeper areas but met in the infralittoral under environmental stress, (c) A transitional zone where degenerating Posidonia meadows are gradually replaced by Cymodocea and Zostera, facies of the muddy sand in sheltered areas biocoenoses (SVMC). This degradation can be attributed to various disturbing factors including natural environmental changes, (d) The biotope of fine well-sorted sands (SFBC). A typical malacofauna is present with the addition of some species. Regardless of the differences, Pérès & Picard's (1964) scheme is more appropriate in the Mediterranean ecosystems than any other northern European scheme.

From May 1993 until January 1994, 788 male and 1604 female crawfish, Palinurus elephas in total, were examined from the South Wales and Cornish fisheries. Mean carapace length (CL) of Cornish crawfish was 125.6 mm for males, 132.4 mm for females and 135.0 mm for berried females, while mean CL for Welsh crawfish was 155.8 mm for males, 138.7 mm for females and 138.6 mm for berried females. The overall size distribution of male Welsh crawfish differed significantly from that observed in the Cornish population. An analysis of variance gave significant (P<0.05) differences for the factors; Site, Sex and the Sex/Site and Month/Sex interactions. Male crawfish reached greater overall size than female crawfish, but for specimens of equal CL, total lengths (TL) of females were longer than those of males. Males were heavier than females of equal CL or TL.

A meeting on Marine biodiversity: causes and consequences was held in York on 30 August – 2 September 1994, organized by the Marine Biological Association and the Scottish Association for Marine Science and supported by the World Wildlife Fund for Nature, the Natural History Museum and the Marine Conservation Society. The following 16 papers were first presented at this meeting.