Small vagile epiphytic crustaceans formed the greatest proportion of the diet of worm pipefish. There were significant differences in the number (Mann–Whitney U=22006·5, P<0·001) and diversity (Mann–Whitney U=11546·0, P<0·05) of prey consumed by male and female pipefish. Harpacticoid copepods are the most numerically dominant form of prey consumed. Further gender analysis of mature pipefish revealed that reproductively mature females and egg-bearing male worm pipefish show significantly greater predatory effort (Kruskal–Wallis H=24·15, df=2, P<0·001). Increased feeding activity, within these groups, is suggested to alleviate the substantial reproductive costs for both female and egg-bearing male pipefish.

The spread of the oil spill from the tanker ‘Prestige’ was analysed in relation to the occurrence of the exceptional 2002/2003 Navidad using airborne and AVHRR satellite measurements. Altimeter-derived geostrophic velocity and Envisat ASAR observations were also used to investigate the structure of this Cantabrian extension of the poleward current around Iberia.

The age of the sea urchin Hemicentrotus pulcherrimus in Oshoro Bay at the northern distributional limit of the species was ascertained by counting black bands in charred genital plates after etching. Consequently, the seasonal growth of two year-classes was monitored and the seasonal changes were related to the reproductive cycle and water temperature. A black band at the edge of the genital plates was found in more than 50% of the sea urchins from September to November. No statistical difference of the test diameter and body weight forming the bands between the estimated and actual values showed that the band is formed annually and can be used as a chronometer. The sea urchin grew rapidly for one and a half months, from late August to late September or early October when water temperature reached a maximum of >20°C, then began to fall while the gonads increased in size prior to maturation. Growth ceased during October to November with initiation of gonadal maturation and the peak of black band formation in genital plates. Spawning occurred from March to May, later than in southern Japan. The annual cycle of growth and reproduction of H. pulcherrimus may be flexibly adapted to surbarctic waters.

Two inshore rocky subtidal sites on the west coast of Scotland (Saulmore Point, Firth of Lorn, 056°27′N 005°24′W and Davy's Rock, Firth of Clyde, 055°46′N 004°53′W) were surveyed for the presence of juvenile (0+) Atlantic cod, Gadus morhua between September 1995 and November 2001. A total of 951 juveniles were recorded at Saulmore Point and 34 at Davy's Rock. At Saulmore Point the abundance was highly seasonal, being observed between June and December only. Juveniles were present in only three out of six survey years, with a maximum abundance of 0·89 individuals m−2 recorded in 1996. Maximum abundance of juveniles at Saulmore Point was negatively correlated with winter seawater temperature, indicating that winter temperatures may be a useful indicator of subsequent juvenile abundance levels in inshore habitats.

The predatory effects of Pachygrapsus marmoratus on populations of the intertidal limpet Patella depressa were analysed on rocky shores located on the central coast of Portugal. Nocturnal observations on crab feeding behaviour were conducted and experimental exclusion cages were set in the substratum to assess density effects on limpets. The results indicated that although crabs feed on adult limpets the predatory level was minimal. Crabs used consistent tactics to detach limpets from the substratum but the majority of the attacks were unsuccessful, possibly due to morphological and behavioural adaptations of limpets. An alternative recruitment hypothesis is advanced to explain non-significant differences between experimental treatments and a possible predatory role on shaping levels of recruitment on lower levels of the shore is considered.

Sex ratio and size–gender distribution of Coralliophila meyendorffii and Babelomurex cariniferus collected in the field was studied. While sex ratio did not depart from the expected Fisher 1:1 ratio for dioecious species, the size–frequency distributions showed clearly a sexual size dimorphism with males significantly smaller than females. Laboratory monitoring of penis reduction in both species, combined with an anatomical and histological study of the reproductive system of individuals reducing penis revealed the existence of transitional sexual stages, proving the existence of protandry. Penis monitoring also demonstrated a high plasticity in size at sex change, suggesting a socially controlled sex change. In C. meyendorffii, where penis monitoring followed an experimental design based on the assumption that protandry existed and that presence of females influenced sex change, results strongly supported a social control of sex change. Evidences for protandry in other coralliophilids are summarized and protandry as a widespread sexual strategy in Coralliophilidae is postulated.

The long term effects of macroalgal canopy removal on community composition were investigated over a 12 year period. Experimental removal of the dominant Ascophyllum nodosum canopy led to short term changes in community composition, the major features of which were still apparent 12 years later. Ascophyllum was slow to recover despite high recruitment, and experimental plots were dominated by Fucus species. After 12 years a mixed assemblage of Fucus serratus, Fucus vesiculosus and Ascophyllum had developed. Canopy removal resulted in a change in the balance between grazing limpets and the cover of red algal turf in the understorey community. The cover of turfing algae declined significantly allowing the area grazed by limpets to extend. This led to a 3–6 fold increase in the limpet population 12 years after canopy removal.

This paper describes a study of the ranging and diving behaviour of two ‘offshore’ bottlenose dolphins, Tursiops sp., in the waters off south-east Queensland, determined using satellite-linked time-depth recorders attached to two animals. Animal 1's tag transmitted for 30 days, Animal 2's for 143 days. Immediately after tagging, Animal 1 swam south, reaching a point 146 km south of the point of tagging, then swam generally northwards until the tag ceased working. Animal 2's observed range covered 778 km2, with a core area of 86 km2. The greatest north–south distance between all locations for Animal 2 was 43 km. The manner in which maximum dive depth was related to dive duration was analysed using constrained principal curves. These analyses indicated that for both animals, short dives were to less than 5 m, and there was no clear relationship between dives of greater duration and depth. These dolphins appear to behave differently from ‘offshore’ bottlenose dolphins studied elsewhere.

The diversity and structure of meiobenthic nematodes and macrobenthic infauna were studied at four widely spaced subtidal sites around the UK coast in relation to a number of measured environmental variables. The stations were situated on soft sediments at water depths of 53 to 95 m and are intended as long-term monitoring locations as part of the UK National Marine Monitoring Programme. Similar benthic assemblages were encountered in comparable environmental conditions. The distribution of nematode and macrofauna species was mainly governed by the geographical location of the habitat and the granulometric composition of the substrate. There was no evidence of any adverse effect on the measures of benthic assemblage structure arising from trace metal concentrations in the sediment, indicating the relatively unpolluted nature of the offshore locations under investigation. Nematode and macrofauna assemblages exhibited stable patterns over time periods of three years.

Multiple locus allozyme heterozygosity has been shown to be weakly, but significantly correlated with certain fitness parameters in bivalves. Immune function of individual Mytilus edulis from the Menai Strait, Wales, UK was assessed monthly over one year (1997–1998) by measuring total blood cell (haemocyte) counts, differential haemocyte counts (% basophils and eosinophils), phagocytic capability (by zymozan uptake) and intracellular superoxide generation. Sampled mussels were also scored at 9 allozyme loci. Mussels were then grouped into multiple locus heterozygosity (MLH) classes and plotted separately against the different measures of immunocompetence. No significant association was present between MLH and total haemocyte count, phagocytic capability or intracellular superoxide generation. However, there was a significant association between MLH and the character (basophilic or eosinophilic) of circulating haemocytes (r2=0·057, P=0·002). Highly heterozygous individuals tended to have significantly more eosinophilic haemocytes circulating in the blood than highly homozygous individuals. Eosinophilic haemocytes are known to have a high capacity for phagocytosis of invading organisms and these results may therefore be interpreted as increased health (=fitness) in more highly heterozygous individuals.

The reproductive cycle of a local population the aspidochirote Holothuria tubulosa in Kaštela Bay (Adriatic Sea) was analysed from July 1994 to August 1995 by histological examination and observations of macroscopic features of the gonads. Five gonadal stages were described: recovery stage, growing stage, mature stage, spawning stage, and post-spawning stage. The distinguishing features used to describe gonad stages in both sexes included the main features of reproductive cells and gonad wall. The reproductive cycle showed a clear annual pattern and was synchronous in both sexes. Spawning occurred during the warm season, from July to September, when the surface water temperature ranged from about 22°C to 26°C. From October to January individuals were in resting phase and had no gonads. In both sexes, variations in maturity indices were related to the seasonal changes in temperature.

The diet of Haliclystus auricula was studied from the gut contents of Stauromedusae collected every two months in southern Chile between November 2001 and November 2002. A total of 3790 medusae were collected and examined. Stauromedusae prey consisted primarily of harpacticoid copepods (68·4%), followed by gammarid amphipods (15·4%), chironomid fly larvae (9·2%) and podocopid ostracods (5·9%). The remaining 1·1% of the diet was made up of empidid fly larvae, polychaete worms, isopods, juvenile decapod crustaceans and gastropods. Gut content was observed in 31% of the stauromedusae collected and only in medusae with an umbrella height greater than 0·4 mm. Frequency of medusae with prey items in their gut content increased with stauromedusae size. The type of prey most frequently found in the smallest medusae were copepods, whilst larger individuals contained mainly amphipods. A strong tendency for the length of prey consumed to increase with medusae size was found.

Vertical posture has been studied only in the scutellid sand dollar Dendraster excentricus although it has been reported in another Dendraster species and two species of laganid sand-dollars. The vertical posture has been associated with the posterior eccentric position of the apical system and petals of the test. We have discovered the scutellid sand dollar Encope michelini, which shows no eccentricity of the apical system and petals, also has the vertical posture in the population studied. Absence of eccentricity of the apical system and petals in living and fossil sand-dollars does not indicate absence of the vertical posture.

The morphogenesis and cytogenesis of the salt gland was studied in various embryonic stages of the viviparous Oman shark, Iago omanensis, from the Gulf of Aqaba, Red Sea. The primordium of the gland is revealed in embryos of 18 mm total length (TL) as a protrusion of the gut posterior to the spiral valve, enveloped in the peritoneal epithelium. In 30 mm TL embryos the glandular parenchyma begins to be organized into secretory tubules extending radially and opening into the central canal of the gland. From this stage on the developments include: thickening of the gland capsule and formation of internal lobules by extensions of connective tissue; strong amplification of the basolateral cell membranes of secretory cells into the cell-cytosols; enlargement of the gland by hypertrophy and hyperplasia of the ion-transporting cells. In 65 (±5) mm TL embryos the gland closely resembles that in adult fish and in pre-term juveniles of 165 (±5) mm TL the gland in general morphology and cytology is identical to that of adults. The results demonstrate that at time of liberation into the environment the juvenile of Iago omanensis is provided for osmoregulation with a functional gland.