A new version of a technique, based on telemetric devices, to monitor temporal aspects of the activity of homing species of limpets and the parallel recording of sea level oscillations is described. The home/away status of individual limpets was continually assessed by means of a magnetic reed switch. Signals from the reed sensors were transmitted to a distant automatic scanner/receiver, located away from the shoreline. The system can be easily replicated and employed for extensive long-lasting monitoring in the field, even in those cases where previous versions, based on cable connections, were unsuitable.

Dynamics of the Abra alba muddy fine sand community of the Rance Basin (western English Channel), initially sampled in one station by Retière at the beginning of the 1970s after the tidal power station built at the mouth of the estuary went into service, was reassessed from 1995 to 1997. Results showed a more ‘mature’ community in 1995–1997 with an increase in the number of species. After a short period, in spring 1995, during which the structure of the community was comparable to those described in 1972–1973, the assemblage was characterized by a great interannual structural stability. Densities of dominant species seem to fluctuate around a mean value comparable to the carrying capacity of the biota for these species. The recruitment of the dominant species with a long life span appears low compared to the densities of adults but seems sufficient to assure the replacement of individuals. Our results suggest that the pattern of massive recruitment followed by high mortality rates could not be the general rule and that a pattern of moderate recruitment followed by low post-settlement mortality of recruits should be more frequent.

The spatio–temporal abundance pattern of 0-group sea bass, Dicentrarchus labrax, was investigated between April 1995 and November 1996 by beam trawl surveys. The highest densities of D. labrax were recorded in shallow areas. Dicentrarchus labrax density was also significantly related to water temperature and salinity, but the variation pattern was not linear. The 0-group individuals of this species first occurred on the nursery ground in May and the highest densities were recorded in June. Diet of 0-group D. labrax was mainly composed of crustaceans, the most important food items being Decapoda, Mysidacea and Isopoda. Feeding activity increased during summer. Short-term variations were related to the period of the day and tidal cycle. The growth rate determined for 0-group D. labrax was higher than those reported for the UK and northern France, and was similar to those obtained in eastern Mediterranean.

This study provides a description of the Mediterranean monk seal (Monachus monachus) diet from the Aegean Sea coast of Turkey. A total of 23 prey items belonging to five species were identified from the two stomachs examined. Cephalopods constitute the dominant prey group by weight (94·01%). Sarcotragus sp. (Porifera) and Posidonia oceanica (Magnoliophyta) are assumed to be incidental prey. Of the cephalopods identified, Eledone moschata and Bathypolypus sponsalis were encountered for the first time in a monk seal stomach.

This is the first report of egg release by the oviparous excavating sponge Cliona viridis. Adult specimens of excavating (α) and massive (β) sponge forms for the presence of oocytes were monitored from 11 May to 12 July 2000, in a shallow-rocky coast of the north-west Mediterranean. The immediate environment around the sponge was sampled for the presence of eggs. Spawning occurred synchronously in the study area at temperatures above 19°C. Oocytes were released in clusters enclosed in adhesive maternal tissue. They contained symbiotic zooxanthellae. Free, adhesive egg-masses drifted in the water or adhered to erect algae in the vicinity of the sponge. Morula stages and larval release are described.

Larvae of Chthamalus malayensis (Cirripedia: Thoracica) from Hong Kong were cultured in the laboratory. Larval development includes six naupliar stages and a non-feeding cypris stage. Larvae reached the cypris stage in 20 d at ∼21°C compared to 14 d at ∼28°C. Morphological features including the cephalic shield, frontal horns, labrum, abdominal process, antennules, antennae and mandibles in all nauplius and cypris stages were described and illustrated using a combination of light microscopy and scanning electron microscopy. Attempts were made to compare morphological differences between the nauplii and cyprid of C. malayensis with those of other Chthamalus species including C. stellatus, C. montagui, C. dentatus, C. fragilis, C. dalli, C. antennatus, C. fissus and C. challengeri. The present description of the nauplii of C. malayensis is not in agreement with the previous description of this species.

There are sporadic records of Thia scutellata from Carmarthen Bay, Cardigan Bay and off the north coast of Wales. Relative scarcity of this small burrowing crab is probably due to habitat specialization. It lives in loose very well sorted medium sand, as typically found in parts of sand waves.

Responses of the Antarctic limpet Nacella concinna (Mollusca: Gastropoda) to meltwater exposure were studied at Adelaide Island (67°34′S 68°08′W). Limpets in crevices could be bathed in pure meltwater, though animals in large pools often avoided significant exposure to lowered salinity because of marked halocline formation. Small pools containing limpets showed extremely demanding osmotic environments with fluctuations between salinities of 3 and 30 psu being recorded within 1–2 min because of alternating meltwater and wave action. Analysis of haemolymph osmolarities in animals taken from the field demonstrated significant falls in osmolality (to 600–800 mOsm kg−1) compared with control animals living in seawater (1000 mOsm kg−1). A few moribund animals had osmolarities <600 mOsm kg−1. Nacella concinna are stenohaline osmoconformers with a median lower lethal salinity (96 h) of 20·9 psu and a median lethal time for freshwater exposure of 2 h 18 min. A 1 h exposure to freshwater caused a 14% increase in body volume and a 27% loss of body fluid ions. Nacella concinna responds behaviourally to meltwater by short-term, ineffective, clamp down of the shell, retraction of the head, cephalic tentacles and mantle margin tentacles. On vertical surfaces limpets respond actively to freshwater exposure by rapid detachment; 50% of animals lose adhesion within 5 min. Consideration of tidal regimes at Adelaide Island suggests that an individual intertidal limpet has a risk of being exposed to severe meltwater exposure about once per year.

This study examined the association pattern of two snapping shrimp species that inhabit burrows at exposed rocky shores of the Chilean Pacific coast. The two species Alpheus inca and Alpheopsis chilensis were frequently found to share the same burrows. In most burrows an heterosexual pair of each species was found. A strong positive correlation between the body length of female and male conspecifics cohabiting in a burrow was found both for Alpheus inca and for Alpheopsis chilensis. Similarly, a positive correlation existed between the mean body length of Alpheus inca and that of Alpheopsis chilensis occurring together in one burrow. Thus, a size-relationship between burrow cohabitants exists both in the intra-specific as well as in the inter-specific association of these shrimps. Most females, regardless of their reproductive stage, were accompanied by males. Within a particular burrow, females of the two species often were in the same reproductive stage, i.e. both were with embryos in a similar developmental stage, or both were without embryos. These data suggest that male and female conspecifics, as well as the pairs of the two species, remain together in the same burrow for relatively long time periods. It is proposed that the intra-specific communication system of snapping shrimp facilitates the development of inter-specific associations, such as the one reported herein.

The beryciform fish Hoplostethus mediterraneus (Beryciformes: Trachichthyidae) is a species discarded from the southern Portuguese coastal fisheries. It is taken as by-catch by deep water trawls, at depths of between 234 and 618 m, more than 80% being taken at depths of between 234 and 422 m. Immature fish ranged from 4 to 13 cm in length and were present at all seasons. Of the mature individuals, males ranged from 7 to 17 cm and females from 7 to 21 cm. From autumn until spring, fish with gonads at various stages of maturation were present, although there were no specimens with mature gonads.

A new species of Branchiomaldane was identified in a collection of polychaetes living in colonies of a stony coral. Branchiomaldane maryae sp. nov. differs from all other species of the genus by the presence of lensed eyes and 1–3 branchial filaments per parapodium. Comparisons between B. maryae sp. nov. and the other species of the genus are provided, together with some phylogenetic considerations on the position of the genus.

In this study, the indirect (i.e. boats not involved in dolphin viewing activities) impacts of boat traffic on the acoustic behaviour of Pacific humpback dolphins, Sousa chinensis, were assessed in Moreton Bay, Australia. Humpback dolphin acoustic behaviour is affected by transiting boat traffic. Boats' passage did not affect the rates at which dolphins produced click trains and burst pulse vocalizations. However, dolphins significantly increased their rate of whistling immediately after a boat moved through the area. This increase occurred only when boats were less than 1·5 km from the groups. Groups including mother–calf pairs showed an increase in whistles in response to boats' passage. Groups with no calves produced significantly fewer whistles. This evidence suggests that the noise from transiting vessels affects dolphins' group cohesion. Mother–calf pairs appear to be most disturbed by transiting vessels, and exhibit an increased need to re-establish vocal contact.

Since the degree of syphonal opening can be an index of the pumping activity, the shape and the surface of syphon openings in Mya arenaria were filmed with an underwater camera at two stations in the middle of the intertidal zone. The individuals were perpendicularly oriented to the main current direction or parallel with the inhalant syphon upstream during flood tide, causing refiltration risks during ebb tide. The surface of the inhalant opening (SI) was strongly reduced with increasing current speeds. Its shape (XI) varied with the individual's orientation and had a tendency to become more circular with time. The surface of the exhalant opening (SE) decreased and its shape (XE) flattened with increasing current velocity and with time. However, variations of XI and XE were weak. Current direction had no significant effect on SI, SE, and XE, but did cause a strong decrease of the SE/SI ratio during ebb in individuals exposed to important refiltration risks during ebb tide. Significant negative correlations between stomach content in phaeopigments and SI and SE suggest that a syphonal constriction could contribute to more efficient feeding. For parallel oriented individuals, the decreases of SE, SE/SI, and XE during ebb can then be interpreted as an attempt to deviate or increase the excurrent velocity relative to the incurrent so as to limit refiltration. We suggest that decreases in opening surface and shape may serve, above all, to increase syphon current jet velocity in syphonate bivalves.

In benthic intertidal studies it is common to standardize species density, and other variables, to a square metre, regardless of the surface area sampled. Using a fully-nested sampling design, with sampling unit surface areas ranging from 0·020 to 1 m2, the present study investigated the effect of this procedure on the accuracy of the results. It is demonstrated that this standardization has a profound influence on the resultant estimates, introducing a substantial error into inter-study comparisons.

In order to find the most suitable parameter for measuring the nereidid Laonereis acuta, correlations between total length or weight and eight morphological measurements: width of prostomium and 2nd, 6th, 13th and 19th setigers, length of the prostomium, length through segment 6th and length through segment 13th, were established. The width measurements showed the highest values of r, and were the most reliable indicators of size. Comparisons between weight and morphological measurements showed a similar pattern as well as negative allometric growth.

The Continuous Plankton Recorder (CPR) survey has collected plankton samples from regular tracks across the world's oceans for almost 70 y. Over 299,000 spatially extensive CPR samples are archived and stored in buffered formalin. This CPR archive offers huge potential to study changes in marine communities using molecular data from a period when marine pollution, exploitation and global anthropogenic impact were much less pronounced. However, to harness the amount of data available within the CPR archive fully, it is necessary to improve techniques of larval identification, to genus and species preferably, and to obtain genetic information for historical studies of population ecology. To increase the potential of the CPR database this paper describes the first extraction, amplification by the polymerase chain reaction and utilization of a DNA sequence (mitochondrial 16S rDNA) from a CPR sample, a formalin fixed larval sandeel.

An automated photographic technique was used to collect quantitative information on the activity patterns of Fissurella crassa under heavy-exposed sea conditions.The activity of this key-hole limpet was confined to nocturnal low tides. Total length of excursions was significantly greater during spring tides than neap tides, as was the maximum distance reached from the refuge. Total duration of excursions and their average speed did not vary significantly according to the spring/neap cycle. While the direction angle of excursions relative to the refuge was not influenced significantly by the spring/neap cycle, the lowest zone within the intertidal was reached by F. crassa during spring low tides only.

Fissurella crassa showed a spatial activity pattern fluctuating intra/inter-individually between a central place foraging and a ranging strategy, with a marked propensity for the former. Looped excursions were characterized by higher speed for the movements away and toward the limpet's refuge, than the movements at maximum distance from the refuge. As the outward and inward branches of looped excursions often overlapped extensively, trail-following is suggested as the main mechanism of orientation used by F. crassa to relocate the refuge.

European lobsters (Homarus gammarus) were sampled from nine sites around the UK coast to determine whether populations could be differentiated on the basis of morphometric variability, and to relate this to depth and indices of population size at each site. Discriminant analysis indicated that exoskeleton damage was the only characteristic that could distinguish males between sites. In contrast, females were distinguished between sites on the basis of variation in exoskeleton damage, claw spines and rostrum teeth, which tended to be positively correlated to indices of population density. This study suggests that female morphology may respond more strongly than male morphology to local selection pressures, albeit in a limited capacity.

Mysids have previously been shown to consume oxygen at much lower rates when in a swarm (cohesive group in which individuals are evenly spaced but not polarized) than when in uncohesive small groups. Thus the swarm represents a strategy for conserving energy. In this study different swarm sizes of mysids were forced to perform escape responses by exposing them to jets of ammonium hydroxide, while measuring their oxygen uptake. Swarms of 200 individuals showed no significant difference in oxygen consumption with or without the ammonium treatment. In contrast, swarms of 100 showed a significant increase of around 45% oxygen uptake when exposed to ammonium. In conjunction with earlier demonstrations of increased feeding success and lower oxygen uptake when aggregated, this work clearly confirms the energetic benefits of being in a larger social group rather than a smaller one or remaining solitary.

The crustacean species composition in the intertidal zones of 13 sheltered unconsolidated marine beaches in south-eastern Brazil is described. Fifty-three crustacean species were collected, adding 46 species to the total reported by previous studies in the same region. Decapods dominated the community, in contrast to exposed sandy beaches where peracarids normally predominate. The species were distributed irregularly among the beaches. Richness varied markedly among sites, and was positively related to a combination of factors such as fine sand grains, high organic matter content, and relatively low silt–clay content. The presence of rock fragments enabled both rocky shore and sandy beach crustaceans to occur on the same beaches. Richness and abundance of crustaceans showed no clear relationship to sediment grain size and slope, in contrast to the norm for exposed sandy beaches. The dominance of the tanaid Kalliapseudes schubarti in some areas may be a result of organic matter pollution in the region. These beaches showed higher species richness than typical sheltered and exposed sandy beaches, indicating that this sheltered, highly heterogeneous seascape is an important area for conservation.