The genus Xenuraega Tattersall, 1909, has been overlooked for most of this century. The rediscovery of Xenuraega now brings the number of genera of Aegidae to six. The genus and the type species X. ptilocera Tattersall, 1909, are described in detail. Xenuraega is characterized by the following apomorphies: antennal flagellum extending beyond pleotelson; mandibular incisor absent, distal mandibular margin fused to cephalon; pleon abruptly narrower than pereon, pleotelson small, not concealing pleopods; uropod exopod reduced to short stub, endopod elongate, styliform, nearly as long as body; pleopods 1–5 not contained within or concealed by pleon and pleotelson.

The annual reproductive cycle and cost of reproduction of the common whelk, Buccinum undatum L. (Gastropoda: Prosobranchia) were studied off Douglas, south-east of the Isle of Man. Sexual maturity was reached at 60–70 mm shell length. Two years of laboratory observation and field data indicated an autumn to mid-winter breeding season. Egg-laying occurred in the laboratory mainly between December and January, and hatching of juveniles between April and early May, 3–5 months after spawning. The cycles of testis and ovary development were very similar, especially during the breeding period. The annual energy invested in reproduction was estimated to be at least 4.1 kj m-2. The investment by females (3.84 kj m-2 y-1) was much greater than by males (0.26 kj m-2 y-1).

Although the English Channel is the northern limit of the latitudinal range of Sphaerechinus granularis (Echinodermata: Echinoidea), this echinoid can produce locally high densities in Brittany, such as in the Glénan Archipelago (Bay of Concarneau) where a small-scale fishery has been exploited since 1985. The reproductive cycle, the growth patterns and the migration of the species in this area were studied from 1988 to 1992. Sphaerechinus granularis presents an annual reproductive cycle with a major spawning in the early spring. But inter annual variability in the time when spawning starts can be observed. A relationship is established between the date of onset of spawning and the climatic conditions during the whole period of gonadal growth. Recruitment is isolated in time and reflects the reproductive cycle.

A study of tributyltin (TBT) uptake, tissue distribution and breakdown in dog-whelks, Nucella lapillus, was carried out using 14C-labelled tributyltin chloride. The compound was introduced into animals by exposure to sea-water, from a diet of labelled mussels and by injection. Measurements of 14C were made on tissue extracts containing total 14C, TBT+DBT and TBT. Organs examined included digestive gland, kidney, mantle, foot, viscera, gonads and blood. Absorption of dissolved TBT occurred primarily via tissues associated with the mantle: autoradiographic evidence showed that of these the ctenidium (gill) and osphradium were probably most important. Of non-reproductive tissues, mantle displayed least evidence of TBT degradation whereas kidney and digestive gland contained lower proportions of 14C as TBT (~60%) than other tissues. By virtue of its more rapid response, initially at least, the kidney had a primary role in degrading dissolved TBT that reached the blood. Dog-whelks feeding on labelled Mytilus edulis absorbed organotins very efficiently via the digestive gland, which then played a major role in TBT breakdown. However, the capacity for degradation is not sufficient to prevent, TBT concentration factors of the order of 100,000 (dry tissue/water) being attained in N. lapillus. Autoradiography revealed surprisingly high grain-counts in nerves, which may be significant in view of evidence in the literature that neurohormones are intermediaries in the chain linking TBT with imposex.

Diets of the two deep-sea species of Mediterranean oplophorids were studied by the analysis of 244 foregut contents of Acanthephyra eximia and 69 of Acanthephyra pelagica. All the specimens were collected on the deep slope (between 610 and 2261 m) using an OTSB-14 bottom trawl.

The diet of A. pelagica consisted of small mesopelagic fishes (Cyclothone braueri, Myctophidae) and bathypelagic crustaceans (Gennadas elegans, Pasiphaea multidentata, Eucopia hanseni, Meganyctiphanes norvegica, hyperiids). In contrast, A. eximia was an important scavenger, feeding on fish remains. Benthic species (polychaetes, Calocaris macandreae, gastropods, etc.) were also detected in its diet. There was little dietary overlap between the two species. In A. eximia bathypelagic decapods were important only in the diet of large specimens. In small specimens the acquisition of decapod prey was not attributable to active hunting. On the lower slope A. eximia was more detritivorous, and predatory activity was lower. This trend was most distinct in small and medium-sized individuals, which predominate at that level.

Between 1984 and 1993, levels of imposex (the induction of male characters including a penis on females) were measured in gastropods Nassarius (Hinia) reticulatus (L.) at localities in south-west England. Since tributyltin (TBT) was thought to cause imposex, concentrations in tissues and sea-water were also determined. Measurements made prior to the restriction of TBT usage in 1987 showed that intensities of imposex were related to TBT levels in females. Tissue concentrations were also related to those of sea-water and concentration factors (dry tissue/water) were approximately 30,000 at 10 ng Sn I-1 and 75,000 at 1 ng Sn I-1. Penis development in females was initiated at about 1 ng Sn I-1 and in this respect JV. reticulatus appears less sensitive to TBT than the dog-whelk Nucella lapillus.

As result of the TBT restrictions, concentrations in sea-water and tissues at some of the more polluted sites decreased by factors of 5–10 times between 1987 and 1993. However, population imposex declined very slowly. This was attributed to the longevity of the snails, the slow decline of penis-length in older females and the limited recruitment of less-affected females.

It was concluded that N. reticulatus is a useful alternative to N. lapillus as an imposex-based TBT indicator at contaminated sites. However, when environmental TBT concentrations are declining fairly rapidly, analysis of N. reticulatus tissues provides a far better indication of change than measurements of population imposex.

A new species of mouthless and gutless free-living marine nematode, Astomonema southwardorum sp. nov., the dominant species from a methane seep pockmark in the North Sea, is described and illustrated. The new species is distinguished by its combination of short cephalic and cervical setae, with the latter being sparsely and irregularly distributed, and also in male specimens by its arrangement of precloacal and caudal setae and its postcloacal papillae. The genus Astomonema Ott, Rieger, Rieger & Enderes, 1982, is rediagnosed. Astomonema brevicauda (Vitiello, 1971) Vidakovik & Boucher, 1987, is considered to be a species inquirenda.

A population of the supralittoral Orchestia gammarellus (Pallas) (Amphipoda: Talitridae), living in a percolating filter of a sewage treatment works has been studied over 12 months. The population showed a seasonal pattern of occurrence, few animals being collected during the winter. The sex ratio was biased significantly to females except during the breeding season when it did not deviate significantly from 1:1. Ovigerous females, never collected in high numbers (1–14 per month), were found from April to August, with peak occurrence in May/June. Juveniles were present throughout the year, but peak recruitment occurred in summer, following the period of reproduction by females. The smallest ovigerous female had a body length of 12.6 mm and the largest measured 20.0 mm. Egg numbers (5–31 per brood) increased with increasing female size and egg volume more than doubled during embryonic development. These findings are discussed in relation to the possible methods of colonization of this unique habitat and the influence of sewage on crustacean life-history traits.

The common whelk, Buccinum undatum L., was selected as a model host-parasite system in a seasonal study at an ‘accumulating’ sewage-sludge dump-site in the Firth of Clyde, Scotland, where marked spatial concentration gradients exist for a variety of trace contaminants in the sediments. A total of 2808 whelks was examined from seven sites over 18 months. The prevalence of larval digenean parasites increased significantly with distance from the dump site from approximately 2% on its periphery to 15.1% at a reference site 3 km from the centre. At a second reference site, 13 km from the dumping area, 19.7% of Buccinum were parasitized. The effects of site, season, sex and parasitism on growth and condition of Buccinum and exposure to sewage sludge on the age-prevalence relationship and host response to infection were examined. Age-frequency distributions of Buccinum were used to compare various sources of mortalities (natural, fishing, pollution and parasite-induced). Patterns in parasite prevalence recorded at the dump site were not correlated with any natural environmental or host-related factors that were examined. The gradient in parasitism in Buccinum is considered to result principally from the toxic effects of trace metals on the miracidium, reducing parasite transmission to the molluscan host. The Bucrinum-parasite system may therefore provide a sensitive and valuable biologically-based index of the dispersal of these contaminants around the sewage-sludge dump-site, and may have wider applications for marine environmental monitoring.

First-stage zoeal larvae of the green (shore) crab, Carcinus maenas (Crustacea: Brachyura: Portunidae), ingested three types of particles offered in sea-water suspensions. In experiments using two types of fluorescent particles (1–2 µm and 1–7 µm ) and living Dunaliella tertiolecta cells (5–7 µm), particles were ingested in at least 40% of the zoeae examined with brightfield, darkfield, and epifluorescence microscopy. These results suggest that green crab larvae may be capable of utilizing planktonic particles in the size range of bacteria, small algal cells, and organically-enriched detrital particles in their natural diet.

Evidence is presented of direct innervation of the secretory cells of luminous glands in the calanoid copepod Euaugaptilus magnus (Wolfenden, 1904). Synaptic structures are present, characterized by specialized pre- and post-synaptic membranes, clusters of synaptic vesicles and pre-synaptic dense bodies. Only one type of synaptic vesicle is present; this is spherical, clear cored and 30–50 nm in diameter. Similar vesicles at synapses in other Crustacea are thought to contain the neurotransmitter glutamate. Each gland appears to be innervated separately and all four secretory cells of each gland are innervated by the same nerve, giving rise to the possibility that control can be exerted over the firing of individual luminous glands.

A new genus, Mesoikopleura, in the family Oikopleuridae (Lohmann, 1915), is described from several specimens collected at low mesopelagic depth (710–860 m) during different cruises using the ‘Johnson-Sea-Link’ submersibles, and from one collected by the ‘Cyana’ submersible during the ‘Gyrocean’ cruise. Three species of this new genus are described: M. enterospira, M. youngbluthi and M. gyroceanis. One of the species already described as belonging to the genus Pelagopleura is moved to the genus Mesoikopleura. Consideration of the genera closely related to Mesoikopleura leads to the division of the subfamily Oikopleurinae into two groups at the level of super genera: Labiata and Alabiata.

A cohort of newly settled Mytilus edulis (L.) (Mollusca: Bivalvia) spat (mean shell length 530 µm) was collected from red filamentous algae at a site on the North Wales coast. After a period of growth in the laboratory, cellulose acetate and starch gel electrophoresis were used to investigate genotype frequencies at the Gpi, Odh, Lap, Pgm, Idh and Mpi loci. Individual testing of each locus, using the X2 test revealed significant deficiencies of heterozygotes at the Pgm, Mpi and Idh loci. However, further testing using a sequential Bonf erroni test, designed to assess the probability of observing at least one significant result from a number of tests by chance alone, revealed that only the deficiency of heterozygotes at Pgm and Mpi loci was significant at the table-wide 95% level. Since post-collection mortality was <3%, these heterozygote deficits must have existed at the time of collection. The conclusion drawn is that heterozygote deficiencies in mussels are generated during the larval stage or at early settlement.

Purified serum immunoglobulin (Ig) from the flounder has been fragmented by treatment with trypsin at 56°C. The major product of the digestion is a protein which resists further degradation over a two-hour period. This fragment constitutes approximately 40% of the Ig molecule and on fully reducing SDS electrophoresis is composed of a single polypeptide chain of apparent molecular weight 33 kD. This is larger than the light chains and therefore indicates that the fragment is derived only from the heavy chains of the Ig molecule. If this fragment is composed of eight polypeptide chains, consistent with the tetrameric nature of the flounder Ig, then its molecular weight is 264 kD. Although its electrophoretic mobility on 4% non-reducing SDS gels suggests a molecular weight of 180 kD, densitometric data support the 264 kD value. The kinetics of the digestion indicate that the first event is the liberation of a 50 kD fragment which is a dimer of two 25 kD polypeptides and which may be a Fabµ fragment.

Samples of two loliginid squids Alloteuthis africana and A. subulata were collected from the continental shelf off the west Sahara in August-September 1987. Statoliths were taken from 124 specimens and processed using statolith ageing techniques. Statoliths of both species were very similar in shape. In the ground statolith, growth increments were examined and grouped into four growth zones distinguished mainly by the width of the increments. Age of adult mature males of both species did not exceed eight months, that of females six months. Alloteuthis africana grew faster than A. subulata in weight and, particularly, in length. At age 180 d the mantle of A. africana was twice as long and the body weight 1·2–1·5 times as large. Both species matured over a wide range of sizes and ages (from 120 to 180 d). The life span of A. africana and A. subulata hatching between January and May on the west Saharan shelf is about six months, much shorter than that of A. subulata in its northern temperate range.

A new species of lugworm Arenicola defodiens sp. nov. (common name ‘black lug’ or ‘runnydown’) is described from 148 specimens taken from intertidal sands around South Wales. Comparisons are made with the well-known and generally more common lugworm Arenicola marina (L.). To aid in diagnosis, a table illustrating differences in the genetics, ecology and morphology is also provided.

The Vestimentifera, or deep-sea tube worms, comprise an ecologically and anatomically unusual group of marine invertebrates, with poorly understood biogeography, ecology, phylogenetic affinities and evolutionary radiation. To gain insight into evolutionary diversification within the group, we have used a molecular biological approach. We report the cloning of a region of 28S ribosomal DNA from representatives of five vestimentiferan genera plus, for comparison, a polychaete and a perviate pogonophore. Phylogenetic analyses using these DNA sequences confirm that Ridgeia and Tevnia are closely related genera. The analyses also lead us to propose the hypothesis that the earliest vestimentiferan lineage to diverge gave rise to the genus Lamellibrachia only. In addition, our comparative DNA sequence data now provide a means to use molecular methods for identification of deep-sea tube worms; we employed this approach to demonstrate that the first vestimentiferan specimen from the eastern Atlantic Ocean belongs to the genus Lamellibrachia. DNA-based identification should have wide applications in the study of vestimentiferan biogeography and ecology.

The relative contributions of the eye, pigmentation (melanophores), and gut contents to the lateral body areas of herring larvae, Clupea harengus L., were measured using a combination of photography and computer image analysis. There was a power relationship between body area and body length (exponent 2.62) which was similar to that of the eye area (exponent 2.57) whereas the pigmented area increased at a greater rate (exponent 4.41). The area of the full gut relative to body length increased at an intermediate rate (exponent 3.04). Melanophores dilated under the effects of anaesthetic, increasing the projected pigment area of herring larvae by an average of 94% after 10 minutes of anaesthesia. These results are discussed in relation to the vulnerability of herring larvae to visual predation.

Tissues of Littorina littorea (Mollusca: Gastropoda) were processed for electron microscopy with an aqueous fixative which included hydrogen sulphide to precipitate intracellular cadmium. The procedure retained cadmium in the cytosol, where it was below the detection limit for x-ray microanalysis, but it did not increase the retention of the metal within lysosomes and other sites of accumulation where it was detectable. Aqueous fixation caused extraction of labile elements, particularly magnesium and potassium, and this effect was increased by the use of hydrogen sulphide. Cadmium and hydrogen sulphide had disruptive effects on the fine structure of cells. It is concluded that cytological fixatives should not include hydrogen sulphide, and that cryo-fixation is required for x-ray microanalysis of intracellular elements.

Methods used to identify individual organisms consistently over time have been invaluable tools in ecological studies, enabling reliable assessments of time-dependent parameters such as growth and mortality, and an accurate determination of their variance. These methods have proved to be particularly amenable to gastropods owing to the presence of an external shell on which marks or tags can be applied with little or no adverse effects on the animal. Marking and tagging techniques have enabled the study of several ecological parameters in adult marine gastropods, including growth (Frank, 1965; Hughes, 1972; Palmer, 1983; Gosselin & Bourget, 1989), mortality (Frank, 1965; Hughes, 1972), movements (Frank, 1965; Chapman, 1986), and foraging behaviour (Menge, 1974; Hughes et al., 1992). Small organisms, however, can pose considerable problems for individual marking (Southwood, 1978). As a result, marking and tagging methods have seldom been applied to newly hatched or recently settled juvenile marine gastropods. Several methods have been developed for simultaneously labelling large numbers of invertebrate larvae (Levin, 1990), and some of these methods may be applicable to juvenile gastropods. The usefulness of these methods, however, is limited because all animals receive the same label and, consequently, individual animals cannot be recognized. To my knowledge, no method of individually marking very small juvenile marine gastropods has been documented. In fact, it is sometimes perceived that small juveniles cannot be individually marked due to their small size and sensitivity (Frank, 1965; Palmer, 1990). The object of this paper is to present a simple method of marking early juvenile gastropods, which consists of applying colour codes to the shells of individuals as small as 0·9 mm in length.