Eight species of polydorid polychaetes were found to inhabit mollusc shells from south-western Australian waters. Numerous individuals of Polydora uncinata were extracted for the first time from the shells of both land-based cultured abalone Haliotis laevigata and H. roei, as well as from natural subtidal H. roei and Chlamys australis. Shells of the oyster Saccostrea commercialis cultured in sea-based systems were infested by Boccardia knoxi which was first recorded in these waters. Polydora aura, Dipolydora giardi, D. armata, D. aciculata and Boccardia proboscidea were common among shells of various natural intertidal and subtidal molluscs. A small number of P. haswelli were extracted from their self-excavated burrows in shells of cultured oysters. Boccardia knoxi and D. aciculata were redescribed based on the newly collected materials. Polydora uncinata and B. knoxi exhibited similar larval development patterns (exolecithotrophy and adelphophagy), iteroparity and longer life span, suggesting a high reproductive potential. This study suggests that further monitoring of polydorid species is needed not only from the viewpoint of marine biology but also to survey the risk invasive species pose to commercially important molluscs in this region and worldwide.

Tributyltin (TBT) pollution has exterminated populations of the dog-whelk Nucella lapillus along most of the north Kent coast (Thames Estuary) but the species survives as a small enclave around the North Foreland. Males in this enclave exhibit an unusual defect involving the non-development or partial development of the genital system: about 10% lack penes, or have undersized penes, and their gonoducts (vas deferens and prostate) are incompletely developed; in some cases, spermatogenesis appears to be retarded. Laboratory-bred animals display the same characters. This deficiency (‘Dumpton Syndrome’) is manifest also in the atypical development of male sex organs on the females (‘imposex’) induced by exposure to tributyltin (TBT). The evidence points to Dumpton Syndrome being a genetic disorder which has lessened the sterilizing effect of imposex and thereby has permitted the survival of this isolated enclave in an area of high TBT pollution.

Since its original isolation and description by Droop in 1953, ‘Monochrysis’ lutheri has proved to be one of the most valuable of cultured phytoflagellates. It has been used by many workers, too numerous to cite, in laboratory studies on phytoplankton growth kinetics, nutrition and biochemistry, and also in mariculture and animal feeding experiments, particularly experiments on the raising of crustacean and molluscan larval stages.

The ratio of the concentrations of κ- to λ-carrageenan is shown to be related to the nuclear phase in Chondrus crispus both in culture and in nature. This ratio is low in tetrasporic plants and relatively high in the gametophytes. It was found to vary somewhat amongst samples analysed, but was always less than unity in tetrasporophytes and greater than unity in gametophytic plants. The κ/λ ratio in Gigartina stellata was high in gametophytes as in C. crispus; the tetrasporophytic phase of this species is unknown. It is suggested that the commercial quality of carrageenan can be correlated with the biological status of the harvested plants.

The organic content of the shells of molluscs can represent a significant fraction of the total organic content (Bernard, 1974) but it is often neglected in calculations of energy budgets in these animals. This may be in part due to uncertainty about the true values, since published estimates of the organic content of shells show quite wide variation. The species examined and also the provenance of the selected samples contribute to this variation as does also the method of measurement. The methods principally used have been by ignition at various temperatures from 400 to 550°C for various durations between 2 and 36 h (see Shumway & Newell, 1984; Jørgensen, 1976; Mohlenberg & Kiorboe, 1981; Vahl, 1981; Shafee, 1979; Price et al, 1976) or by acid extraction using different extraction proceedures (see Ivell, 1979; Dame, 1972; Horn, 1986; Griffiths & King, 1979). To calculate the energy content of the organic component some investigators have used the Hughes (1970) coefficient of 5.037 cal mg-1, while others have used Paine's (1971) protein coefficient of 2.39 J g-1. Wilbur & Saleuddin (1983) have called attention to the need for more study of these analyses. We present here the results of a study of the shell organic content of three species of molluscs, using two methods for the measurement and giving data on biochemical composition and energy value.

The permeability properties of the silvery walls of the swimbladders of eels (Conger conger and Anguilla anguilld) have been studied. The intact swimbladder wall is very much more impermeable to carbon dioxide, oxygen and nitrogen than ordinary connective tissue. Removal of the silvery layer of the wall, which contains crystals of guanine with a little hypoxanthine, increases the permeability about 100 times and leaves a transparent ‘epithelial’ layer only a little less permeable than connective tissue to these gases. The wall of the pneumatic duct of the conger swimbladder, which is not silvered, has permeability properties similar to those of connective tissue. In long-lasting experiments a production of carbon dioxide not coupled to oxygen usage was detected in the epithelial layer. The ratios between the diffusion constants of CO, N and O for both the silvery and epithelial layers show that diffusion probably takes place through water-filled pathways, and calculations show that impermeable overlapping crystals embedded in the silvery layer could account for its very low permeability. Two deep-sea eels were shown to have swimbladders whose walls contained about 10 times more guanine/unit area than the conger eel. The possibility that layers of guanine crystals may divide fish into compartments is discussed.

Just before spawning the semen of the herring is isosmotic with the parent blood, the eggs are hyposmotic. Immediately the eggs are placed in sea water of salinities 5, 17·5, 35 and 50 %0 there is a change in the freezing-point of the yolk indicating that it has approached close to being isosmotic with the water. Changes in the freezing-point of the yolk during development indicate that the overgrowing embryo gradually regulates the osmotic concentration of the yolk, although full regulation is not achieved until after the closing of the blastopore. After this point there is no significant change in the freezing-point of the yolk or body fluids. Regulation is most probably brought about by the activity of the cells of the ectoderm.

Studies of a natural population of N. virens Sars at Southend reveal that the oocytes take a little over a year to mature. After a period of relative quiescence they grow rapidly between September and December and then increase little in size until early May. Within a given specimen small oocytes are more variable in size than large ones. Sperm develop fully from coelomic sperm plates in about eight months, and are mature by the beginning of May. There is a period during which they are characteristically clumped in quartets.

The age and growth rate of Modiolus modiolus have been studied from acetate peel replicas of polished and etched shell sections. Age estimates could be reliably obtained from the alternating patterns of light (summer) and dark (winter) growth lines present in the middle nacreous layer of the shell. Growth lines in the inner nacreous layer, however, generally converged to form blocks of nacre such that the identity of individual lines was lost, whilst in the umbones growth lines were often tightly compressed and difficult to resolve. Data obtained from analyses of the internal growth lines in the middle nacreous layer were used to construct growth curves for several subtidal populations using the von Bertalanffy growth equation. The fastest growth rate was recorded for mussels growing epifaunally on the legs of a drilling platform in the North Sea; these mussels achieved a maximum shell length of 110 mm within ten years. The oldest mussel (from Ling Bank in the northern North Sea) was 48 years old and measured 133 mm in length whilst the largest mussel (from Loch Spelve in western Scotland) was 147 mm long and 38 years old. With the exception of the relatively young population (maximum age 10 years) from the drilling platform, most of the benthic populations studied included mussels in excess of 35 years of age. It is clear, therefore, that M. modiolus is a potentially long-lived member of the subtidal benthos.

Here we present evidence of seasonal reproduction in the deep-sea vent mussel Bathymodiolus azoricus, a dominant member of the Mid-Atlantic Ridge (MAR) hydrothermal fauna in the Azores region. This is the first time that seasonal reproduction has been suggested for any deep-sea vent organism. This discovery was made possible by the use of novel, acoustically-retrievable cages, which allowed us to extend the frequency and temporal range of sampling that was previously limited to the summer months. The main spawning peak, at the Menez Gwen vent field (840 m) occurs in late December–January and shows a correlation with a winter–spring bloom in primary production in the euphotic zone. Our results suggest that this surface-derived material may act as both a food source for the dispersing mussel larvae and as a reproductive cue/supplementary nutritional source for the adult mussels. Further evidence of a dependence on photosynthetic inputs comes from the relationship between particulate feeding levels, which themselves correlate with the phytoplankton peak, and the amounts of storage tissue in the mantle, which ultimately gets converted into gonad. Thus, the pattern and energetics of reproduction in the Atlantic vent mussel B. azoricus closely resembles that found in the coastal mussel Mytilus edulis, which has been described as an adaptation for optimizing the timing of reproduction against a background of seasonally-varying food availability. This discovery emphasizes the complexity of the nutritional pathways found in some deep-sea chemosynthetic environments and highlights the need for more time-series studies.

Time-lapse video was used to record movement paths of Strongylocentrotus droebachiensis on a rocky bottom at 8 m depth, both at a grazing front and in recently formed barrens in the wake of the front. Urchins did not exhibit strong directionality in movement and we did not detect any differences in movement variables between the front and barrens. Density of conspecifics had a negative effect on the speed, move length (distance), and daily displacement of urchins, but did not significantly affect the proportion of time spent moving, the linearity index and the number of moves taken per day. The frequency distributions of turning angles between moves and steps were non-uniformly distributed, indicating directionality in individual paths. A correlated random walk model was used to predict the displacement of urchins through time and provided a good fit with observed data. Our results provide insight into the foraging behaviour of S. droebachiensis and are consistent with previous observations of small-scale movement in this species.

Winkles dwelling on horizontal surfaces orientate by means of a lightcompass reaction. As the tide recedes, most of the tracks in the sand are towards the sun but after a time each animal reverses its direction of crawling, so tracing out a roughly U-shaped path which leads it back, approximately, to its starting-point.

When kept in an aquarium winkles tend to settle on the sides above the waterline and to become inactive. When stimulated, as by immersion, they crawl downwards, then horizontally and then upwards before settling above the waterline.

Winkles collected from horizontal surfaces at first show no tendency to climb vertical surfaces in an aquarium. After a period which varies from a few hours up to 10 days they do climb the sides of the tank. Animals collected from vertical surfaces climb the sides of the aquarium at their first opportunity and then settle. It can be concluded that winkles have an inherent tendency to climb and settle in the head-up position on vertical or steeply sloping surfaces but that if this opportunity is denied them they become habituated to horizontal surfaces.

The minimum angle to which winkles can react by gravitational responses is of the order of 10–20 degrees.

In an aquarium starved winkles prolong their excursions below water when presented with suitable food but fully fed animals respond less strongly to the stimulus of immersion.

Dark-adapted winkles from horizontal surfaces are at first positively phototactic, but after a time varying from 15 to 20 min, they become negatively phototactic. Tested with the ‘two-light’ experiment most animals disregard the second light (telotaxis).

Studies of the larval nervous system of two species of starfish were carried out using antisera to a recently isolated native echinoderm neuropeptide, GFNSALMFamide (S1), and to serotonin. S1-like immunoreactivity was found in the larvae of the asteroids Pisaster ochraceus and Asterias rubens (Echinodermata: Asteroidea), originating in the apical region and becoming concentrated as two groups of cells in the dorsal ciliary band, the preoral transverse and adoral ciliary bands in larvae up to the early brachiolarian stage (five weeks). The pattern of serotonin immunoreactivity, although appearing earlier in the apical nerve plexus, is very similar to that of the peptide, with paired groups of immuno- reactivity apparent in the dorsal ciliary band. This evidence, together with other recent studies, indicates that this neuropeptide is present in both the larval and adult nervous system, despite the complete reformation of the system at metamorphosis. The close localization of SI with serotonin may also suggest a possible function for the peptide in larval and adult nervous systems.

We present the most comprehensive cytochrome oxidase subunit 1 gene tree published to date for demosponges based on new sequences. The CO1 barcoding fragment is sequenced for 65 species from the Caribbean Sea, and its gene tree reconstructed. Although its deeper nodes are not particularly well-supported, the gene tree provides a variety of information for new phylogenetic patterns, as well as support for previously published 28S rDNA gene trees. In our analysis Halichondriidae cluster with Suberitidae, supporting previous 28S rDNA data. Chelae-bearing Poecilosclerida are monophyletic but most taxa lacking chelae in this dataset cluster more distantly. Haplosclerida are not resolved monophyletically under this fragment. While some species exhibit distinct barcodes, some genera contain species that share CO1 haplotypes.

The taxonomic status and nomenclature of the hermaphrodite forms of Fucus (other than the alga currently known as F. spiralis L. and certain hybrid forms) usually included under the name Fucus inflatus L. by European authors, but under several specific names by N. American and some other authors, is discussed. It is considered that the numerous forms described are best interpreted for the present as forms of a single, extremely plastic and widely distributed species.

The dry weight condition index and water content of two groups of mussels, one with heavy infestations and the other with mild infestations of Polydora ciliata, were determined over a period of 15 consecutive months. The results were seasonally variable, but for most months the heavily infested mussels had a condition index significantly lower, and a water content significantly higher, than the mildly infested mussels. This suggests that heavy infestations of P. ciliata are associated with reduced flesh content in mussels.

Further analyses of the body components of the two groups of mussels, showed that the mantle tissue of heavily infested mussels was reduced much more than the nonmantle tissue. Since the mantle is the main repository of gametes, this suggests that heavy infestations of P. ciliata might lower the fecundity of mussels.

The following short descriptions of several of the eggs and larvæ of Plymouth prosobranchs, hitherto unknown or imperfectly known, are brought together, although many of them are not fully worked out. It is hoped in the near future to publish a general account of the British species with reference to all known forms, including those which have been specially described from Plymouth.

Some of those described below have not yet been identified, but it is thought that it is worth while noting them for the benefit of future workers, especially some striking forms, important in the plankton on account of their size. This is notably the case with the three larvæ probably belonging to the Turridæ.

Structure and climate of the east North Atlantic are appraised within a framework of in situ measurement and altimeter remote sensing from 0°–60°N. Long zonal expendable bathythermograph/conductivity–temperature–depth probe sections show repeating internal structure in the North Atlantic Ocean. Drogued buoys and subsurface floats give westward speeds for eddies and wavelike structure. Records from longterm current meter deployments give the periodicity of the repeating structure. Eddy and wave characteristics of period, size or wavelength, westward propagation speed, and mean currents are derived at 20°N, 26°N, 32·5°N, 36°N and 48°N from in situ measurements in the Atlantic Ocean. It is shown that ocean wave and eddy-like features measured in situ correlate with altimeter structure. Interior ocean wave crests or cold dome-like temperature structures are cyclonic and have negative surface altimeter anomalies; mesoscale internal wave troughs or warm structures are anticyclonic and have positive surface height anomalies. Along the Eastern Boundary, flows and temperature climate are examined in terms of sla and North Atlantic Oscillation (NAO) Index. Longterm changes in ocean climate and circulation are derived from sla data. It is shown that longterm changes from 1992 to 2002 in the North Atlantic Current and the Subtropical Gyre transport determined from sla data correlate with winter NAO Index such that maximum flow conditions occurred in 1995 and 2000. Minimum circulation conditions occurred between 1996–1998. Years of extreme negative winter NAO Index result in enhanced poleward flow along the Eastern Boundary and anomalous winter warming along the West European Continental Slope as was measured in 1990, 1996, 1998 and 2001.

The long-term monitoring of two stations, 55 and 80 m depth, from 1971 to 1985 shows clear evidence of periods of stability interspersed with periods of change. These periods were identified by several different multivariate methods and persistence stability was quantified by the use of a between years similarity index. A short period of change at the shallow station, 1972–3, was followed by a prolonged period of stability 1974–80. The period 1981–3 witnessed a second period of change with rising total numbers and biomass with some evidence of a downward reversal in 1984–5. The deep station exhibited an essentially similar response except that the stable period 1974–80 was broken into two sub-periods 1974–6 and 1978–80 due to sequential changes in the dominant species which were regarded as evidence of biological interaction with the activities of the polychaete Ophelina acuminata possibly playing a key role. The shallow station showed little evidence of biological interaction and the majority of the species have exhibited similar responses throughout. The general rise in numbers and biomass at both stations is regarded as evidence of intermittent changes in organic flux to the bottom from the water column. The winter temperature fluctuations were shown to have short-term, but significant, effects on the diversity of the communities, bringing about year to year changes in the equitability and dominance.

Jellyfish (Cnidaria: Scyphozoa) are increasingly thought to play a number of important ecosystem roles, but often fundamental knowledge of their distribution, seasonality and inter-annual variability is lacking. Bloom forming species, due to their high densities, can have particularly intense trophic and socio-economic impacts. In northern Europe it is known that one particularly large (up to 30 kg wet weight) bloom forming jellyfish is Rhizostoma spp. Given the potential importance, we set out to review all known records from peer-reviewed and broader public literature of the jellyfish R. octopus (Linnaeus) and R. pulmo (Macri) (Scyphozoa: Rhizostomae) across western Europe. These data revealed distinct hotspots where regular Rhizostoma spp. aggregations appeared to form, with other sites characterized by occasional abundances and a widespread distribution of infrequent observations. Surveys of known R. octopus hotspots around the Irish Sea also revealed marked inter-annual variation with particularly high abundances forming during 2003. The location of such consistent aggregations and inter-annual variances are discussed in relation to physical, climatic and dietary variations.