A new species of physonect siphonophore, Halistemma transliratum sp. nov., is described from two specimens collected at mesopelagic depths in Bahamian waters by the submersibles ‘Johnson-Sea-Link’ I and II, and comparisons are made with the established species of that genus.

In direct-transfer temperature tolerance experiments, Lasaea rubra was found to have a median lethal low temperature of – 3.5°C and a median lethal high temperature of + 39°C. If introduced to temperatures slowly, survival at extreme temperatures was improved, particularly at freezing temperatures; > 92°0 of animals survived at – 10 °C and + 40 °C if introduction from a holding temperature of + 18 °C took place over at least 1 h.

Lasaea rubra are active at salinities between 15 and 60‰, indicating considerable tolerance of changes in body fluid osmolarity. In week-long exposure experiments more than 50 % of animals survived all salinities from 0 to 150‰; tight shell valve closure was maintained at extreme salinities.

When exposed to declining salinity, Lasaea rubra progressively isolates its tissues from the environment as salinities fall below 18–20‰, and maintains shell valve closure below 8‰. These responses are symmetrically reversed in response to rising salinity.

Salinity discrimination in Lasaea rubra is based upon sensing of external osmolarity, not external ionic concentrations.

The littoral prawn Palaetnon elegans Rathke regulates the body concentration of zinc at higher external zinc concentrations in the presence of EDTA. The dissolved zinc concentration in artificial sea water corresponding to the threshold of regulation breakdown changed from ca. 100 μg Zn 1-1 (ca. 1.53 μmol Zn 1-1) without EDTA, to ca. 316 μg Zn 1-1 (ca. 4.8 μmo1 Zn 1-1) in the presence of 8.6μmol EDTA 1-1 at 10 °C. The regulated body Zn concentration remained unchanged at 77–79 μg Zn g-1 dry wt with or without EDTA. Increased levels of EDTA in the medium decreased the rate of uptake of labelled zinc by P. elegans. The presence of 3 μmol EDTA 1-1 decreased the mean Zn uptake rate of prawns in 100 fig Zn 1-1 (ca. 1.53 μmol Zn 1-1) from 2.9 to 0.25% of total body Zn g-1 day"1 at 10 °C. The increased ability of P. elegans to regulate zinc in the presence of EDTA may be explained by the reduced bioavailability of the zinc-EDTA complex for uptake. There is marked individual variation in the rate of uptake of labelled zinc in prawns, even in the presence of the same concentration of zinc or zinc-EDTA.

The starfish Anseropoda placenta (Pennant) is abundant in the gravelly sands of the Bay of Brest (Finistere, France). The size, distribution and density of this animal were evaluated along a transect perpendicular to the River Aulne in the southern part of the Bay. The spawning phases, the recruitment and growth processes were defined. When the entire population was considered, three plurimodal year classes were visible from the length frequency histograms. Year-class segregations were observed. Their density varied in space and time in a manner which suggests a pattern of migration from the southern part of the transect towards the northern part. Juveniles were recruited mainly during the autumn on the gravelly bottom of the southern shallow part. By late winter, they had migrated to the deeper parts of the channel. Feeding preferences do not seem to be the main factor controlling these migrations which are discussed in relation to environmental factors and the intra- and inter-specific competition.

The paper presents preliminary data on the response of Pectinaria koreni to light and on the effect of light and temperature on its rate of sediment reworking. Pectinaria at the ‘settling in’ stage reacted to light by burying themselves completely under the sediment. There was indication that vertical movement of Pectinaria in the sediment followed a diurnal rhythm probably associated with feeding activity. Pectinaria was most active at higher temperatures and in the dark. At 7 °C the rate of sediment reworking was significantly less than that at 10 and 15 °C and was not affected by light. At 10 and 15 °C the amount of sediment reworked in the dark was significantly greater than that reworked in the light.

The mechanisms of accumulation of zinc and cadmium by the marine polychaetous annelid Neanthes arenaceodentata (Moore) have been studied. Animals have been exposed to EDTA chelate buffered sea water containing 65Zn and 109Cd. The calculated free ion activities of the zinc and cadmium in the sea water were 10-8.13 M and 10-7.65 M, respectively. Uptake occurs from the free ionic pool of metal and EDTA and EDTAmetal complexes are largely excluded from the animal. In unfed animals, the metals accumulate linearly with time at a rate which decreases when the temperature is reduced but increases in the presence of metabolic inhibitors. Experiments using [14C]EDTA as an extracellular marker indicate that the observed increase in accumulation caused by the inhibitors is at least partially due to media entering extracellular anatomical compartments such as the coelom and lumen of the gut which are normally isolated from the seawater by cilia or sphincters.

Glass eels of the American eel Anguilla rostrata (Lesueur) utilize selective tidal stream transport, a series of semidiurnal vertical migrations in phase with the tide, to migrate up the Penobscot River estuary, Maine, U.S.A., in the spring. Glass eels, freshly collected during their migration, exhibited rhythmic activity with circatidal periodicities when tested in groups in the presence of a water current under constant conditions in the laboratory. Freshly collected groups of eels which had already completed their migration through tidal water did not exhibit circatidal activity rhythms under the same conditions. The activity rhythms of groups of eels freshly caught in tidal water appeared to be entrained by a 12.5 h cycle of water current reversals, but not by a 10.0 h cycle of current reversals. In other entrainment experiments water collected on flood and ebb tides was alternately added to the experimental tanks every 5.0 h. Under these conditions groups of eels freshly caught in tidal water did not display any rhythmic activity. Only 2 of 100 glass eels, freshly collected from tidal and non-tidal water, which were tested individually in static tanks, exhibited rhythmic activity. The activity rhythms would allow an eel to time its vertical migrations in the estuary despite varying environmental conditions.

The effect of increasing the temperature of Mytilus edulis by 10 °C is to increase the rate of 65Zn uptake. If the temperature is oscillated through this range there is a further enhancement of metal uptake. The effect is associated with a decrease in cytosol metal and an increase in granular fractions. These unexpected results are interpreted in terms of cellular metal-ligand homeostasis.

Two sabellariid polychaetes, Sabellaria alveolata from European waters and Phragmatopoma californica from the west coast of North America, are known from previous work to have larvae that settle and metamorphose preferentially on the cemented sand tubes of conspecific adults. The naturally occurring inducers of larval metamorphosis were recently isolated and identified for P. californica. In the present study, larval behaviour of S. alveolata and P. californica was compared in reciprocal laboratory settlement assays. For both species, metamorphosis occurred to a greater extent on conspecific tube sand than on control sand or on heterospecific tube sand. Extraction of the tube sand of S. alveolata with organic solvents diminished its capacity to induce metamorphosis pi conspecific larvae, but this capacity was not transferred to the extracts, as was the case for P. californica. The substance responsible for the enhanced metamorphosis of S. alveolata on conspecific tube sand remains unknown. The free fatty acid (FFA) inducers of larval metamorphosis of P. californica either inhibited, or had no effect on, metamorphosis of S. alveolata. Both species responded abnormally upon exposure to unnaturally high concentrations of certain (particularly polyenoic) FFAs. Abnormal larval responses of S. alveolata, however, did not incorporate behavioural components of normal metamorphosis, as were observed for P. californica. FFAs were isolated from the natural tube sand of S. alveolata at less than one-tenth the concentration found in the natural tube sand of P. californica. The differences between the two species provide further evidence that a very specific mechanism is responsible for the perception of FFAs by the larvae of P. californica.

In an attempt to describe the physical and chemical characteristics of the sediments as an environment for the invertebrate benthos, a total of 273 stations covering the sector from 56° N to 61° N in the North Sea was sampled. The sediment samples which were collected by grab and corer were analysed for particle size (as well as silt-clay content and sorting), organic carbon, plant pigments and trace metals (Cd, Pb, Zn, Ni, Co, Cu). On a smaller scale a few stations were sampled for redox potential, pH and pesticides.

Taking into account the geological history and the on-going hydrographic processes, explanations for the formation of the sedimentary provinces in the North Sea were provided. The sediments were predominantly fine to medium sand, but there was a depth-related gradient with the finer grades, organic carbon and, to a lesser extent, plant pigment being found in the deeper sedimentation basins of the Fladen Grounds and Norwegian Trench.

Trace metals and pesticide contaminants associated with the finer organic and inorganic fractions were higher in the sediments of the above deeper areas as well as in the vicinity of estuaries. It could be concluded that despite the enhanced concentrations of Cd, Ni, Pb and Co, at the east of Shetland, which were due to a geochemical anomaly, there was no evidence of any important or large-scale contamination of the North Sea as a whole.

All groups of meso- and macro-zooplankton in the North Sea off Northumberland, at a depth of 53 m, were studied during a 15-year period (1969–83); copepod productivity was estimated from biomass and growth rates. Phytoplankton were seasonally bi-modal with peaks in April and August–October; copepods were uni-modal peaking in June–July. The predatory zooplankters: larval fish, decapods, ctenophores, medusae (the summer-autumn predators) peaked between May and September, while chaetognaths and euphausiids (the winter predators) peaked in December–January. Copepods and the summer-autumn predators were seasonally and inter-annually positively correlated, and declined in abundance from 1974 to 1980. Euphausiids and chaetognaths on the contrary increased in abundance during these years, and were seasonally and inter-annually negatively correlated to the copepods. The mean annual abundance of copepods was positively related to the previous winter's minimum, and inversely related to the abundance of chaetognaths and euphausiids. Annual copepod productivity averaged 1260 kJ m-2 year-1, and showed no relationship to other groups of plankton.

The physiological rates of a normally omnivorous marine rotifer, Encentrum linnhei, were measured under the steady-state chemostat conditions in which the physiological state of the food-algae was kept constant whilst the rotifer growth rate was changed to preset levels. The specific clearance rate ranged between 50 and 100 μl/μg rotifer C/day (1.5–3.0 μ/rot/day) and varied hyperbolically with growth rate, a similar curve was obtained with the specific ingestion rate which varied between 1–2 μg C/μg rot C/day. A mean respiration rate of 0.45 μg C/μg rot C/day was obtained from oxygen consumption measurements. About 60‰ of ingested energy was found to be egested as paniculate matter and 9–4 °0 dissipated as heat, the latter comparing with a theoretical figure of 4–5‰.

From rates, transfer efficiencies were obtained giving a mean net growth efficiency (K2) of 38‰ and a mean overall growth efficiency (K1 of 15‰. A curvilinear increase of Kl with growth rate contrasts with linear and hyperbolic responses found with brachionid rotifers.

Scale readings from 6269 bass caught in 1946–86 on various parts of the U.K. coast, with a few from the Channel Islands and France, have been analysed to determine U.K. growth patterns and assess the relative abundance of successive year-classes. In the U.K. growth was fastest on the south-east coast, slowest on the west coast. In the Channel Islands growth was initially slower than on the south-east coast but faster after maturity; though less fast than on the Biscay coast of France. Year-classes of exceptional abundance tended to grow more slowly than classes of normal abundance. There was evidence in each region of a slight long-term fall in growth rate. Best growth occurred in warm summers. The growth period commenced, and annulus formed, at dates ranging from early May for the youngest juveniles to mid July for adults; terminating in each case in October. Males grew rather more slowly than females and appeared less long-lived and less hardy, except on the south-east coast, where, exceptionally, samples were caught well offshore and included large, generally faster growing fish; this suggests a behavioural difference between the sexes rather than consistently slower growth in males. Explanations are offered for occasional fast growing fish, which occur mainly on the south-east coast and mainly with particular year-classes, notably 1966 and 1969. Problems of interpretation are considered and solutions offered.