The importance of egg and larval mortality in the determination of year-class strength was discussed at a colloquium at La Jolla, California in 1975 (see Hunter, 1976). In addition to the obvious effects of starvation, predation and disease, pollution by such substances as copper is an important factor affecting viability. The copper concentration in sea water is generally about 1–2,µ/l. Chester & Stoner (1974), in a comprehensive survey, found an average copper concentration of 0.8µ/l in the open ocean and 0.9 µg/l nearer the shore. In British waters Preston et al. (1974) reported a range of 1.1–1.6 µg/l and Portmann (1972a) found a range of 1–20 µg/l with the possibility of 1000 µg/l near sea-bed copper deposits.

Ridgeia piscesae from a hydrothermal vent and lucinid and thyasirid bivalves from inshore Canadian and UK waters, known to contain sulphur-oxidizing symbiotic bacteria, had lipids rich in 16:0,16:l(n-7) and 18:l(n-7) fatty acids in both bacteria-rich trophosome or gill tissue and in tissues without symbiotic bacteria. The results are consistent with the animals deriving these fatty acids from their sulphur-oxidizing symbionts. Ridgeia piscesae, Lucinoma annulata, Parvilucina tenuisculpta, Lucinoma borealis and Myrtea spinifera also contained substantial amounts of the non-methylene-interrupted dienoic fatty acids 20:2δ5,13 and 22:2δ7,15. It is proposed that these fatty acids are produced by chain elongation and δ5 desaturation in animal tissues of 18:l(n-7) produced by the bacterial symbionts. Thyasira flexuosa did not contain 20:2δ5,13 or 22:2δ7,15 but instead contained 18:l(n-ll) and 20:l(n-13) which were not present in the other species analysed. It is proposed that 18:l(n-ll) and 20:l(n-13) arise from the δ9 desaturation of 20:0 and 22:0, respectively, followed by chain shortening of the mono-unsaturated fatty acid products of δ9 desaturation. It is considered that 20:2δ5,13 and 22:2δ7,15 are formed in the animals in response to a relative excess of 16:0, 16:l(n-7) and 18:l(n-7), accompanied by a relative deficiency of (n-3) and (n-6) polyunsaturated fatty acids. The results are discussed in relation to the lipid nutrition of marine invertebrates containing bacterial symbionts.

The production of larvae by Ostrea edulis L. was studied in collections made from brooding females obtained from oyster grounds on the east, south and south-west coasts of England and from the Menai Straits. The size of the brood was directly related to the size of the oyster, but considerable variation was found from oysters of the same size whether measured as diameter, volume between the shells or dry meat weight. Part of the scatter was due to variation in condition of the oyster at spawning; oysters in good condition at the time of spawning produced more eggs than those in poor condition. This cause of variation was also seen in different populations; those with a high average condition index had a higher average fertility than those in poor condition, although the correlation was not quite significant at the P = 0.05 level (r = 0.632). It is presumed that most of the remaining variation is of genetic origin.

Fertility was related to size rather than age, although it is suggested that in some old slow-growing oysters it may be reduced. No decline in fertility was found as the breeding season progressed, nor was there clear evidence that larvae are liberated at a smaller size late in the season.

A comparison of the average size of broods at an early stage of development with those that were nearly mature showed that there was no loss of larvae during brooding. Samples of shelled larvae from 204 broods were measured; less than 10 % exceeded 190 µ size.

The death assemblage of molluscs (gastropods and bivalves) from the sandy beach at Harlyn Bay, north Cornwall is shown to be fully representative of the biodiversity of the regional species pool from all habitat types. The biodiversity measures used are average taxonomic distinctness (Δ+, the average degree to which species in an assemblage are related to each other) and variation in taxonomic distinctness (Λ+, the evenness of the spread of taxa across the taxonomic spectrum). A late Pliocene fossil assemblage of molluscs from St Erth Pits, north Cornwall, UK, is also not significantly different in biodiversity, in these terms, from the present-day regional species pool. The climate in the late Pliocene was similar to the present-day Mediterranean, suggesting that predicted changes in climate, by the end of this century, will not affect molluscan biodiversity, although the species composition will undoubtedly change.

The tenacity of cypris larvae of the barnacles (Crustacea: Cirripedia) Balanus perforatus (Bruguiere) and Elminius modestus Darwin was measured on multispecies biofilms developed under contrasting shear regimes. For both species, relatively thin, dense biofilms associated with high shear (83 s-1) afforded increased tenacity over relatively thick, less dense films associated with low shear (15 s-1). Although both species showed reduced tenacity on low-shear films compared to high-shear films, E. modestus cyprids attached as strongly to low-shear films as they did to unfilmed surfaces. Balanus perforatus cyprids, however, attached less strongly to low-shear films than to unfilmed surfaces. The results show that B. perforatus and E. modestus may appreciate differences in bacterial communi-ties grown under different shear conditions and highlight the potential for biofilms as one of the many cues to barnacle settlement.

The distribution, abundance and feeding behaviour of sea urchins (Paracentrotus lividus, Psammechinus miliaris, Sphaerechinus granularis) and the macro-algal biomass were assessed in two maerl beds within a north-east Atlantic coastal ecosystem (Bay of Brest, Brittany, France). To study the possible control of herbivorous sea urchins on the macrophytic algae, one maerl bed under the influence of urban sewage (northern site) was compared to one less influenced by urban and industrial outlets (southern site). Macrophytic biomass in the northern site was estimated as 40-fold higher than in the southern site where sea urchins were, on average, 38-times more numerous. Preliminary results support the hypothesis that grazing of sea urchin, even in low densities, can be a factor regulating the macrophytic biomass on maerl beds except in too nutrient enriched environments. So in the northern basin of the Bay, data pointed out the role of anthropogenic impacts on macrophytic biomass increase which was concomitant with the progressive disappearance of sensitive herbivorous species like sea urchins, both processes result in change in the ecosystem.

This study describes the spectral characteristics between 250 and 700 nm of lenses from 71 species of deep-sea teleost. The majority of these did not contain detectable amounts of short-wave absorbing pigment and transmitted all longer wavelengths to the same extent before cutting off smoothly and rapidly in the near-UV (50% transmission 310–348 nm). The lenses of 15 species, however, contained significant amounts of short-wave absorbing pigment. The majority of these lenticular pigments had smooth ‘bell-shaped’ absorbance spectra with a single peak in the near-UV. Such ‘simple’ pigments were extracted from four species (λmax: 360·8 nm, 36·50 nm, 395·7 nm, 324·8 nm) and detected in a further eight species, although insufficient material was available to allow their extraction from the latter group.

The absorbance profiles of lenses from another three species were more complex, suggesting the presence of one and two carotenoid-like pigments respectively in the lenses of Argyropelecus sladeni and A. affinis, and two as yet unidentified pigments in the lenses of Malacosteus niger. This brings the total of short-wave absorbing pigments so far described in the lenses of deep-sea fish to at least eleven. In Argyropelecus spp. the pigmentation was most pronounced in the lens cortex, while in Malacosteus niger it was restricted to the lens core. In all other species the pigment appeared freely diffusible throughout the lens. Several species showed an increase in the degree of lenticular pigmentation in older animals and two (Argyropelecus affinis and Malacosteus niger) demonstrated age-related changes in the relative concentrations of two different pigments within the lens.

Despite the widespread occurrence of Eurydice pulchra Leach on sand beaches along the Atlantic coasts of Europe and around Britain (Jones & Naylor, 1967), there has been no detailed work on growth and reproduction in this species until a recent account by Salvat (1966), who carried out investigations on breeding populations of this species and the closely allied E. affinis at Arcachon, south-west France. Apart from this there are some brief generalized observations on the reproductive cycle of E. pulchra in ecological studies upon the fauna of sandy beaches (Watkin, 1941, 1942; Scott, 1960; Lagardère, 1966), and some reference to reproduction in other species of the genus is given by Fage (1933), Bacesco (1948), and Soika (1955). In view of some contrasting accounts given by previous authors and the lack of detailed observations on British material, present investigations were carried out into the reproduction and life cycle of E. pulchra and E. affinis in South Wales. Estimates of the reproductive potential of each species are made and discussed in relation to actual population densities recorded on the beaches.

As a result of work by Pirlot (1933), Newell (1948), Smidt (1951) and Duncan (1953) it has become accepted that on European coasts the lugworm has a restricted breeding season occurring only in the autumn. Previously, several workers had stated that this species also spawns in the spring. Kyle (1896) reported that at St Andrews spawning took place between January and March and again between July and September. Similarly, Gamble and Ashworth (1898) and Ashworth (1904) found that on the Lancashire coast the laminarian variety spawned in the spring, although the littoral variety spawned during late summer.

The family Monhysteridae is characterized by 17 valid genera, seven of which are known to be free-living, inhabiting marine sediments. In total, 70 valid marine species are ascribed to these seven genera. Overall, the family is characterized by a confused taxonomic history with a large list of synonyms and species inquirendae. The taxonomic problem is not restricted to the old literature, but inconsistencies also appeared in recent studies. The aim of this study is to show the most important diagnostic characters to identify each genus and provide taxonomic tools for species identification. Dichotomous-keys and illustration-guides are attempted for the marine monhysterid species. For the family and each subfamily, tribe and marine genus a brief historical background, diagnosis and a list of valid species is provided. Hereby, we propose to transfer eight species of the genus Thalassomonhystera to the genus Monhystrella.

Many of the calanoid copepods contain large amounts of neutral lipid that is predominantly wax esters (Lee, Hirota & Barnett, 1971; Lee & Hirota, 1973; Sargent & Garten, 1976). The role of these compounds in the life-history of copepods is particularly well documented for the large Northern Pacific calanoid Euchaeta japonica Marukawa. These animals have their highest levels of total lipid (50% of the dry weight) at stage V, up to 80% being wax esters (Lee, Nevenzel & Lewis, 1974). Wax ester levels are lower in adult females but are high in the eggs, the contents of which are subsequently used during the naupliar stages (Lee et al. 1974). Thus, wax esters accumulated during the later developmental stages provide a fuel for the developing eggs and embryos; from which it follows that the amounts of these lipids present in mature animals are likely to be critical in determining the brood size and survival of the ensuing generation. So far, however, the factors controlling lipid levels in copepods have been poorly understood.

The common cockle Cerastoderma edule is intermediate host to several species of digenean trematodes. However, little is known about the factors influencing the settlement of trematode larvae in cockles as well as their effects on the host. Aspects of the transmission ecology, behaviour and effects on juvenile host specimens of trematode larvae belonging to the genus Himasthla and utilizing mudsnails Hydrobia ulvae as their first intermediate host and various waterbirds as their definitive host have been studied. Cercariae of Himasthla spp. (more than 90% of the metacercariae were identified as H. continua post-experimentally) exhibited a host size-dependent selection within the host size range from 2 to 6 mm. Infection efficiency was reduced by the presence of substratum allowing cockles to burrow, suggesting that the foot and visceral region may be attacked by cercariae. No increased mortality due to parasite infections could be demonstrated within 5 d after infestation. The metacercariae within experimentally infected cockles were primarily located in the connective tissue within the foot and visceral region. Although some cockles were completely filled with metacercariae only small functional effects were detected, such as a slightly prolonged burrowing time of infected specimens.

This study provides the first compilation on age and growth of some delphinids in south-eastern Brazil (18°25′S–25°45′S). A total of 154 delphinids were reported: 44 Atlantic spotted dolphin Stenella frontalis; 36 bottlenose dolphin Tursiops truncatus; 26 ‘Brazilian’ common dolphin Delphinus sp.; 20 rough-toothed dolphin Steno bredanensis; 16 Fraser's dolphin Lagenodelphis hosei; 3 false killer whale Pseudorca crassidens; 3 unidentified Stenella sp.; 2 pantropical spotted dolphin Stenella attenuata; 2 short-finned pilot whale Globicephala macrorhynchus; 1 spinner dolphin Stenella longirostris; and 1 striped dolphin Stenella coeruleoalba. Age was estimated by counting the number of growth layer groups present in the dentine in 74.5% of the sample. The growth of 92 individuals of the first five species was determined by the Gompertz model to length-at-age data. Stenella frontalis—the oldest specimen was 23 y and the asymptotic length of 224.4 cm predicted by growth curve occurred at about 20 y; T. truncatus—the oldest specimen was 26 y and the asymptotic length of 301.3 cm predicted by growth curve occurred at about 20 y; Delphinus sp.—the oldest dolphin was 18 y and the asymptotic length of 215.9 cm predicted by growth curve occurred at about 5–6 y; S. bredanensis—the oldest specimen was 24 y and the asymptotic length of 258.1 cm predicted by growth curve occurred at about 10 y; L. hosei—the oldest specimen was 19 y and the asymptotic length of 231.2 cm predicted by growth curve occurred at about 7–8 y. Only age was estimated for the other species. The age-at-length data for S. frontalis, Delphinus sp., S. bredanensis and L. hosei were consistent, suggesting a good agreement with previous work on these species. For T. truncatus, the age at asymptotic length obtained in this study might be confirmed by increasing the sample size. The information currently presented will contribute to further life history research of delphinids on the western south Atlantic coast.

Spirorbis corallinae sp.nov. is very similar to S. borealis but can be distinguished by its orange colour, small size, bifid opercular talon and particularly by the fact that the larvae choose to settle on Corallina officinalis rather than on Fucus serratus.

Other species dealt with, in a key to identification and notes on distribution, are S. granulatus, S. malardi, S. pagenstecheri, S. rupestris, S. spirillum and S. tridentatus.

The discovery of a shallow water (<2 m) foraging site off the Greek Island of Kefalonia, where diving and foraging behaviour of male loggerhead turtles (Caretta caretta) could be observed simultaneously, was of great interest. The preferred food sources were shown to be the bivalve mollusc Mytilus galloprovincialis, the sea grass Posidonia oceanica, and the entrails of fish discarded by local fishermen. Whilst foraging, the turtles generally rested on the seabed and employed their forelimbs to clear away detritus from their selected prey. Foraging dives were of short duration (mean ±SE = 2.3 ±0.43 min, N=96) compared to deeper dives reported in the literature presumably, because of the small lung volumes required to attain neutral buoyancy at such shallow depths.

Veliger larvae of the nudibranch mollusc Adalaria proxima are triggered to metamorphose to the benthic form by the adult prey bryozoan, Electro pilosa. Ion substitution and supplementation experiments with artificial sea water (ASW) have, however, shown that metamorphosis can be induced by elevation of the potassium ion concentration alone. Approximately 19 mM K+ASW (10 mM ‘excess’) was found to elicit maximal metamorphic responses: 29 and 39 mM K+ASW had no inductive effect. Choline chloride was also found to induce metamorphosis in a dose-dependent manner, with lO M ineffective, 10 M approximately threshold, and 5×10 M to 10 M optimal. Concentrations of choline >10 M were sub-lethally toxic. That the absence of larval metamorphosis on exposure to 29 and 39 mM K ASW was due to inhibition is inferred from interaction experiments with choline: at these concentrations of K, metamorphosis in response to choline could be abolished. Timed-exposure experiments indicated that artificial induction elicited by elevated K and choline involve either separate mechanisms, or different parts of the same pathway. Thus, whilst larvae required to be continuously exposed to 19 mM K ASW in order to complete metamorphosis, those exposed to 10 M choline would subsequently complete development in normal ASW following only 1–2 h exposure to the inducer. Preliminary experiments failed to specify further the nature of the natural inducer, beyond the confirmation that live intact colonies of the bryozoan Electro pilosa will trigger larvae to metamorphose.

Geographic variation of allele frequencies at four loci in Chlamys opercularis was investigated using electrophoresis on polyacrylamide gels. Large differences were observed between populations at a protein locus, while some small but significant variations occurred at the phosphoglucomutase-2 and octopine dehydrogenase loci. The leucine aminopeptidase locus appeared monomorphic. On the basis of mean genetic identities derived from three loci in nine populations and hydrographic data on coastal current systems, it is proposed that there are at least four relatively genetically isolated populations of this scallop around the British Isles, namely (1) North and West Scottish coast, (2) the Irish Sea, (3) the Celtic Sea (Brittany coast) and (4) the English Channel. It is argued that both random genetic drift and selection may play a significant part in the establishment and retention of large allele frequency differences between isolated populations of this species.

Genome size (or C-value) in benthic polychaetes was studied from both experimental data and literature. Nuclear DNA content variation was analysed as related to both phylogenetic relationships of various families, general life habit of the species (interstitial vs macrobenthic), diploid chromosome number (2n), and mean body size (length). Experimental data on genome size were obtained for 43 lower taxa (genera and species) by means of microdensitometric analysis of the amount of Fuelgen-stained haploid DNA in interphase nuclei. These data, added to those available in the literature (36 taxa studied by Conner et al., 1972) gave a total of 79 taxa (genera and species), representing 30 families and 14 orders. Twenty-one of the species studied belonged exclusively to interstitial (=meiofaunal) families or genera.

The development of the olfactory system, taste and sensory buds of the Dover sole (Solea soled) during metamorphosis has been studied by light and electron microscopy and preliminary correlations with changes in feeding behaviour have been made.

INTRODUCTION

During metamorphosis, the feeding behaviour of the Dover sole changes considerably. In the early larval phase, the fish swim pelagically, feeding on plankton using their visual sense, while the metamorphosed fish become more active at night, finding food by means of their chemical senses (for a review of the literature, see de Groot, 1971). However, previous observations have shown that sole are capable of feeding in the dark from the very early hatching stage (Blaxter, 1969) and also that at the time of first feeding, the majority of the larvae remain close to the bottom where they appear to ingest particles (Rosenthal, 1966; Fluchter, 1966).

patterns of distribution and abundance of giant sea anemones and anemonefish were compared among coral reefs along the coastline of sinai in the northern red sea. the sea anemones varied widely in abundance between reef areas containing different habitat types. they were rare on steep reef slopes with abundant coral cover (=low-density anemone sites, 0.09–0.68 anemones per 1000 m2 of reef area), but were common at a site containing patch reefs interspersed with sand (=high-density anemone site, 6.00–8.11 anemones per 1000 m2). distributions of the endemic two-band anemonefish (amphiprion bicinctus) varied significantly between the two main host anemone species. at the high-density site, individuals of the sea anemone heteractis crispa either did not contain anemonefish, or were occupied by single juvenile fish as shown in previous studies. at low-density sites h. crispa usually hosted clusters of juvenile anemonefish. in contrast, individuals of the sea anemone entacmaea quadricolor hosted either single adult fish (high-density site) or pairs of breeding adults (low-density sites), frequently in addition to some juvenile fish. mechanisms that prevent anemonefish from reaching adult size and forming breeding pairs in h. crispa may include high fish mortality above a size threshold because this host cannot adequately protect them from predation when they become large, active emigration of fish to e. quadricolor as described in previous reports, and/or environmentally-controlled cessation of fish growth. we conclude that in the northern red sea, individuals of h. crispa potentially serve as nurseries for anemonefish.