Preliminary examination of marine meiofauna from the Plymouth area, especially on mesopsammic representatives, resulted in the finding of several typically interstitial Mollusca. Among them, Caecum glabrum, Hedylopsis spiculifera, and Philinoglossa praelongata were recorded live for the first time in the area. This is also the first record of Ph. praelongata outside the Mediterranean Sea.

During a short stay at the Marine Biological Association Laboratory some preliminary studies on meiofauna were made. To obtain information especially about the interstitial fauna of marine sand, three typical samples of coarse sediment from different positions were examined.

Sample A: Plymouth Sound, Outer Cawsand Bay, Queens Ground, 50°20' 03“ N, 4° 10' 27” W; ca. 6 fathoms (=11 m); coarse sand, about 6 1 examined (14 September 1982).

Sample B: Plymouth Sound, southwest of Drake Island, 50° 21' 06“ N, 4° 09' 50” W; ca. 7 fathoms (= 13 m); coarse shell-sand, about 1 1 examined (15 September 1982).

Sample C: outer Plymouth Sound, 50° 18' 51“ N, 4° 10' 30” W; ca. 12 fathoms (– 22 m); fine gravel, about 1 1 examined (15 September 1982).

In this contribution only the gastropods are dealt with; other meiofauna will be treated ina later communication. The sole previous report of mesopsammic fauna from the Plymouth area is that of Spooner (1959). He examined two samples, one of which (Plymouth Sound) was taken fairlyclose to the above sample A, about 18“ more to the West at 4–5–5–5 fathoms (8–10 m; G. R. Forster, personal communication).

The free living eulimid gastropod Melanella alba Bowdich, 1822 is a temporary ectoparasite on echinoderms and, in Kilkerrin Bay on the west coast of Ireland, this species is found exclusively associated with the holothuroid Neopentadactyla mixta (Östergren), 1898. Melanella utilizes a highly specialized acrembolic proboscis to penetrate the integument and ingest the internal tissues of this holothuroid. That portion of the proboscis which penetrates integument bears a highly developed secretory epithelium composed of granular and goblet secretory cells. As the proboscis is unfolded into the host's integument by a combination of increased hydrostatic pressure and muscular movements, secretory material is released from this epithelium and appears to bring about a rapid loosening of the connective tissue elements of the host. The possible mechanism by which the integumental connective tissue is altered to allow unfolding of the proboscis into the coelomic cavity of the host is discussed.

Mussels, Mytilus edulis L. grow on the shore and are cultured on ropes in Killary Harbour, a fjordic inlet on the Irish west coast. The food resource available to cultured mussels differs from that available to wild mussels on the shore. Although phytoplankton densities as estimated from chlorophyll a concentrations are similar, the shore environment in the inner part of the inlet is characterized by high mean POC concentrations. This is because of the presence of variable amounts ofallochthonous detrital carbon.

The annual cycles of flesh weight and ash content of wild and cultivated mussels were followed over two years. These cycles were related to the reproductive cycle observed by taking histological samples of mussel gonad, by plankton sampling for larvae and by monitoring larval settlement. Shell growth was measured in wild mussels by reading seasonal growth patterns on sectioned shells and in cultured mussels by following progress of the modal shell length of cohorts on ropes.

Wild mussels have a partial spawning in early spring and spawn completely in the summer. Cultured mussels spawn twice during the summer, in the year following settlement. Growth rate of wild mussels decreases with increasing aerial exposure. The fastest growing mussels, at o % exposure, take about 6 years to attain the length attained by the mode of the cultured mussels after 18 months, when they are harvested.

We conclude that wild mussels utilize a mix of phytoplankton and detritus as food during the summer and that large wild mussels can use detritus during the autumn and early winter for an increase in flesh weight and gametogenesis.

An examination of the proportions of pedal disc colour and isozyme phenotypes, in samples of Actinia equina L. collected from around Britain, has shown that individuals which are heterozygous for a gene complex involved in morph determination occupy a habitat intermediate in position to those occupied by the two homozygotes. It is concluded that A. equina may best be considered as comprising three morphs, rather than two as had been distinguished previously.

As the abundance of anemones in samples displaying a particular pedal disc colour phenotype decreases, the proportion of these individuals which possess atypical combinations of colour and hexokinase-i phenotypes increases. This result is interpreted as indicating that individuals are subject to differential selection in different habitats, dependent upon their genotypes at hexokinase-i, or those at some other tightly linked locus.

Introduction

Our recent work on Actinia equina L. has revealed the existence of two morphs amongst anemones collected from British coasts, having column coloration ranging from red to brown (Quicke, Donoghue & Brace, 1983). One morph displays pedal disc colour (coloration) (PDC) ranging from red to pink (R), and occurs in the upper part of the intertidal range of this species, where it is commonly found firmly attached to vertical rock faces. The other has a grey (G) or green (H) pedal disc, which may sometimes display contrasting red or orange radial lines (L); these colour phenotypes will be collectively referred to as GHL. This latter morph occurs predominantly at a lower tidal level, where it usually occurs on horizontal surfaces to which it adheres relatively weakly.

Oxygen consumption was measured in squid (Illex illecebrosus) ranging from 42·7 to 443·0 g. Ambient temperature increased from 8·3 °C to 18·2 °C during the experimental period. Resting rates were calculated by correcting for the percentage of time not spent in the resting posture. A 100 g squid resting at 13 °C has a predicted oxygen consumption of 31·3 ml/h, while a continuously swimming squid has an oxygen consumption of 125·0 ml/h. Oxygen consumption is almost directly proportional to body size. A 10° increase in environmental temperature would increase oxygen consumption for a squid of given mass by 6·7 times.

Guanine and hypoxanthine were excellent sole nitrogen sources for several microalgal species grown in axenic culture. Of the algae studied only Chlorella stigmatophora grew well on pyrimidines. Freshly harvested nitrate or ammonium-grown organisms generally lacked ability to take up guanine or hypoxanthine but this ability developed during several hours of photosynthesis in nitrogen-free medium. Nitrate-grown (but not ammonium-grown)Tetraselmis subcordiformis and Chlorella fusca could take up guanine, the initial rate of uptake increasing when the cells were also nitrogen-deprived. Of the algae studied only Chlorella vulgarisand Attheya decora required prior incubation with guanine before being able to take it up. Porphyridium purpureum did not take up guanine. Factors affecting the development of ability to take up guanine and the characteristics of guanine transport were studied. The transport systems showed Michaelis-Menten type kinetics with K s values ranging from 05 to 3–7/IM guanine. In marine species, guanine uptake was dependent on the presence of Nations in the medium but Chlorella stigmatophora showed less dependence on Na+ than other species.

Cell-free extracts of Phaeodactylum tricornutum contained a methyltransferase which catalysed the methylation of guanine or hypoxanthine by 5–adenosyl-methionine. The product ofthe reaction appeared to be a methylhypoxanthine irrespective of whether guanine or hypoxanthine was substrate. This enzyme activity (per unit protein) trebled during 6 h of nitrogen deprivation. It is suggested that this enzyme is responsible for the methylation of guanine and hypoxanthine when these are taken up by nitrogen-deprived intact cells. Uricase, allantoinase and allantoicase were present in cells incubated with guanine, hypoxanthine, uric acid or allantoin;these activities did not appear during nitrogen-deprivation. Crude cell-free extracts containedaninhibitor of uricase and activity could be demonstrated only after ammonium sulphate precipitation of protein. When these three enzymes were induced by incubation with guanine, their order of appearance was identical to the order in which they operate in purine catabolism, namely (i) uricase (ii) allantoinase (iii) allantoicase. Guanine deaminase, xanthine oxidase and xanthine dehydrogenase activities were not detected irrespective of whether cells were nitrogen-deprivedor incubated with purine.

Four squid species from around Scotland and in the northern North Sea were examined for larval ascaridoid nematodes maturing in warm-blooded vertebrates. A larval contracaecinean (possibly Contracaecum osculatum) in Loligo forbesi, and Anisakis simplex L in L. forbesi, Alloteuthis media and Todaropsis eblanae are recorded, apparently for the first time. Neither of the inshore neritic myopsids L. forbesi and A. media appears to be an important host of Anisakis simplex L3. The oceanic oegopsid Todarodes sagittatus showed the highest A. simplex L3 burdens; whilst the general pattern of infection in this species was similar to that of teleost fish in the northern North Sea, the density of infection was lower. The possible significance of L3 in squid for the population dynamics of A. simplex is discussed. Larval ascaridoid nematodes in squid may have no public health significance in the U.K.

Males of Eledone cirrhosa grow to a size little over 600 g and normally have well-developed, and presumably active, reproductive organs from about 200 g upwards. Total weight of the genital bag is well correlated with total body weight (r= 0·906). Growth of the testis precedes that of the spermatophoric sac, and the size of neither of these reproductive components is predictable from body weight. The sizes of these organs and the estimated number and length of stored spermatophores are given for 100 g intervals of total body weight. No evidence was obtained for a seasonal trend in male maturity.

Female Eledone cirrhosa held in aquarium conditions for periods of time of five daysand over show relatively enlarged ovary sizes. Values for ovary index considerably exceed thoseof freshly caught animals and the incidence of the final stage of maturity, in which eggs pack the oviducts, is greater. A comparison of maturity indices for fresh and aquarium males was inconclusive. The range of factors associated with aquarium conditions is briefly reviewed and it is concluded that studies of cephalopod reproductive maturation must distinguish fresh and aquarium animals.

Introduction

External factors effective in inducing sexual maturation in cephalopods have been suggested several times. The influence of the absence of light has been implicated since the experiments of Wells & Wells (1959) showed that blinded Octopus vulgar is matured precociously. An effect of short day length in stimulating the optic glands of Sepia has been found by Defretin & Richard (1967) and Richard (1967) but this is not clearly the case for Octopus (Buckley, 1977). Octopuses kept in aquarium conditions for lengthy periods are said to have larger relative gonad sizes than those fresh from the sea (Wells & Wells, 1975). One of the factors associated with aquarium conditions is often a degree of starvation, and this circumstance alone is held to be a factor in inducing precocious sexual maturation in Eledone (Mangold & Boucher-Rodoni, 1973).

In the course of recent studies on the growth and reproduction of Eledone cirrhosa from the North Sea (Boyle & Knobloch, 1982,1983,1984) animals which had remained in aquarium conditions for 5 days or over were separated from the analysis.

Samples of the deep-sea forcipulate seastars Brisinga endecacnemos, Brisingella coronata, Freyella spinosa and Zoroaster fulgens have been collected at a number of stations in the N.E. Atlantic. Examination of their reproductive biology suggests subtle interspecific variations in their gametogenic cycles. The gonads of Brisinga endecacnemos are serially arranged under the dorsal arm surface, each cluster of gonad tubules having its own gonopore. In the closely related Brisingella coronata each gonad consists of up to 12 elongate tubules opening at a single gonopore at the dorsal surface. In both species the maximum egg diameter is about 1250 μm and fecundity may be up to 60000 eggs per individual. It appears that the eggs in Brisinga endecacnemos are produced in clusters whilst those of Brisingella coronata are produced continuously. InFreyella spinosa the gonad consists of a small tubular sac analogous to a single tubule of Brisinga endecacnemos. Maximum fecundity is only 2500 eggs per individual, and the maximum egg size is 1250 μm. In all three species eggs that are not spawned undergo internal oocyte degeneration. The gonads of Zoroaster fulgens show the typical asteroid configuration of two at the base of each arm, one either side of the ambulacrum. The maximum oocyte diameter is 950 μm. There is some evidence that there may be a seasonality of reproduction in this species. In all four species examined the large egg size and relatively low fecundity suggest direct demersal development with the subtle variations in their reproductive biology reflecting slightly different breeding habits.

Kingsnorth Power Station, on the River Medway Estuary, Kent, discharges cooling water into a canalcomprising a 4 km creek system. A comprehensive investigation of the sublittoral benthic fauna of the discharge system was undertaken from January 1979 to September 1981. The benthic macrofauna was sampled monthly at five stations along the system and a sixth in the River Medway adjacent to the creek mouth (DC4); salinity, sea-bed temperature, sediment particle size, sediment redox potential, residual chlorine and meiofaunal numbers were measured. The macrofauna is significantly suppressed at sites along the discharge canal, representing a community with half the number of species as at station DC4, comprising dense populations of a few dominant opportunistic species tolerant of thermal stress (e.g.Tubificoides, Cauleriella), and not those characteristic of organic pollution stress communities. The latter are regular summer immigrants in the creek, but persist only in low numbers if at all in the winter (e.g.Polydora ciliata). This suppression is the result of a 10°C temperature front between the heated discharge water and ambient estuarine water, passing over the sea bed with the ebbing and flooding tide four times each day. The residual gradient of mean temperature along the discharge canal causes some changes in the dominance of those species not eliminated by the temperature front. These temperature effects are expected to be localized, mainly in the area of sea-bed impingement of the discharge water; they are predicted to occur at any thermal discharge in tidal waters where the heated effluent contacts the sea bed.

Elminius modestus Darwin 1854 is a small, estuarine barnacle, until 1940 found only in New Zealand and southern Australia but now well established in Europe. Using electrophoresis, 22 enzymes were compared between 10 populations of E. modestus from Europe and three populations from the Antipodes. Fourteen enzymes gave consistent, scorable results at 19 loci, of which 10 were monomorphic. Contingency comparisons of allele frequencies at the polymorphic loci showed no significant difference within the European samples, within the Antipodean samplesand between the European and Antipodean samples. These results were discussed in the context ofboth the history of the spread of the species and its planktonic larval phase. It seems likely that the species spread to Australia by remote dispersal from New Zealand before 1832, and thatthe initial settlement in U.K. waters in the 1930s must have been large enough to establish thespecies successfully with a genome representative of that of the mother population, at least atthe loci examined.

An account is given of a commonly accepted method for measurement of the gill area of fishes. A number of practical hints are included together with some warning about possible sources of error. In particular, these include sampling methods and reduction of errors due to shrinkage. Emphasis is given to the importance of weighting in the calculation of gill area. Problems which arise in comparisons of gills from different species are discussed and attention is drawn to possible errors that can be introduced by the reduction of all data to a given body weight offish. Such dangers are especially present where comparisons are made between fishes which may differ in weight by as much as four orders of magnitude.

A series of samples were taken during the period 1975–81 in successively deeper 250 m bathymetric zones between 400 and 2900 m depth in the Rockall Trough. The bathymetric centres of distribution of the gadoid species are at shallower depths than those of the morid species. Micromesistius poutassou and Gadiculus argenteus thori exploit the pelagic and benthopelagic resources at depths shallower than 750 m depth. Molva molva andMolva dypterygia dypterygia are primarily fish eaters, the latter occurring deeper than the former. Phycis blennoidesand the rarerAntonogadus macrophthalmus are epibenthic feeders. Among the morids, the benthopelagic feeding Antimora rostrata lives primarily at depths of 1500–2500 m. Halargyreus johnsonii and the more common Lepidion eques both live at 750–1000 m depth but exploit different resources in the benthopelagic and epibenthic regimes.

Fourteen species of benthic invertebrates, found to be indicators of hydrographic conditions by Blacker (1957), were recorded during research cruises between Finmark and north Spitsbergen during the summers of 1978, 1979, 1980 and 1981. The distributions were compared with those found during surveys carried out between 1949 and 1959.Both Atlantic and Arctic species were found to the north of Bear Island and along the west coast of Spitsbergen, and the temperature ranges at which they were found were greater than those found by Blacker (1957).

Introduction

During the past century the annual mean temperature of the Arctic regions has undergone a considerable change. The warming of the regions began about 1885 (Willett, 1950) and peaked around 1938, when the mean air temperature of Spitsbergen was nearly 6 °C warmer than at the turn of the century (Hoel, 1953). The warming of the seas in the region seems to have started later - Jensen (1939) suggests 1917 - and sea temperature changes were detected north of Spitsbergen in 1921 (Schokalsky, 1936). This warming resulted in the reappearance of cod in great quantities on the Bear Island Bank, after the absence of any sustained quantities for about 40 years (Blacker, 1957).

The marine benthos of Svalbardf was surveyed during the latter part of the last century and the first half of this century (1878–1914,1923–31) when the benthos was recorded during several cruises in the region (see Blacker (1957) for review). The benthos was again recorded between 1949 and 1955 (Blacker, 1957) and 1955 and 1959 (Blacker, 1965); see Fig. lA.

It is conclusively shown that cyprids of the barnacle Balanus balanoides (L.) use a secretion released onto the antennulary discs for temporary attachment. This secretion does not stain with conventional histochemical techniques but was shown to be proteinaceous by staining blue in Bio-Rad protein-dye reagent normally used in protein assay. The discovery of this proteinaceous secretion adds further evidence to suggest that cyprids use a form of Stèfan adhesion for temporary attachment during exploration prior to settlement.

Introduction

Although recent advances have been made in the measurement of cyprid temporary adhesion (Yule & Crisp, 1983), the question of the precise mechanism has remained speculative. Earlier suggestions that the attachment organs of the antennules operated by suction (see Saroyan, Lindner & Dooley, 1969) were challenged on morphological grounds by Nott & Foster (1969) and finally disproved by the force measurements of Yule & Crisp (1983).

Nott (1969) and Nott & Foster (1969) were able to show numerous unicellular glands opening out, individually, onto the surface of the antennulary disc arranged in two concentric rings, one near the margin, and the other around the central sense organ. It was considered that these glands could produce a tacky secretion used for temporary adhesion. Yule & Nott (unpublished, reported in Yule & Crisp, 1983) failed to find any traces of such a tacky secretion on glass surfaces after cyprids had walked across them. To establish the presence or absence of a fluid secretion on the antennulary disc is fundamental to the further understanding of the type of temporary adhesion employed by cyprids.

Spatial pattern of settlement of cyprids of the barnacleBalanus balanoides (L.) was examined from photographs taken every low tide during the first 20 days of the settlement season. The locations of pits and cracks and the bases of detached adults were mapped in order to measure specificity of settlement in relation to surface contour and chemical cues associated with conspecifics. Cyprids were identified as to their date of settlement. Distances to nearest neighbours were computed for newly settling cyprids relative to each other, for newly settling cyprids relative to previously settled cyprids, and for newly settling cyprids relative to newly metamorphosed spat.

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.

The development of a unispecies bloom of phytoplankton in the Rade de Villefranche (N.W. Mediterranean, near Nice) during June 1982 coincided with the disappearance of salps from the area. A phytoplankton haul was taken on 24 June and examined in detail. The sample consisted of virtually a unispecies diatom population; Rhizosolenium spp., together with a few small medusae and crustaceans. The diatom cells were unusual in that they appeared to be associated with large amounts of extracellular mucus.

The appearance of this virtually monospecies bloom provided a rare opportunity to examine in detail the biochemical composition of a natural field diatom species (see discussion in Ballantine, Lavis & Morris, 1979 and Morris, 1984). After removal of zooplankton the phytoplankton were collected on a 30 μm clear nylon filter. A detailed biochemical analysis was carried out as previously described (Morris, McCartney & Robinson, 1983; Morris, 1984).

The Rhizosolenium spp. sample was composed of almost equal amounts of lipid (23 mg), insoluble carbohydrate (19 mg) and protein (24 mg) with much smaller amounts of soluble carbohydrate (009 mg). The lipid was composed mainly of polar lipids (70% total lipids), neutral glycerides (20% total lipids) and sterols (8% total lipids). The detailed fatty acid and sterol composition of these major lipid fractions are shown in Tables 1 and 2.