An ecological assessment of Fecampia erythrocephala, reporting its habitat distribution, abundance, host specificity, size-specific prevalence, frequency distribution among hosts, effect on host growth, and its site specificity within these hosts is presented. At the Isle of Man and near Plymouth, Fecampia erythrocephala cocoons were generally abundant on the undersides of rocks in the Ascophyllum and Fucus serratus zones. Infected crabs were also most common in these habitats. Both Carcinus maenas and Cancer pagurus were parasitized at similar prevalences, although the former species was relatively much more common in the habitats where the worm cocoons were abundant. Fecampia erythrocephala did not infect crabs larger than 11 mm carapace width, and prevalence decreased significantly with crab size. Prevalences reached 11% in areas where cocoons were abundant. Together with the large size of these worms relative to the size of the host crabs and the observations on worm emergence, these life history features indicate that F. erythrocephala is a parasitoid of young shore crabs. Fecampia erythrocephala cocoon abundance is often high in localized areas and size-prevalence information suggests that worms mature rapidly in these crabs. This suggests that F. erythrocephala is an important contributor to crab mortality and to the ecology of shore crabs at these sites.

Measurement of the respiration of Nucula nitidosa and N. nucleus determined that N. nucleus had a respiration rate approximately a third greater than that of N. nitidosa, 215·28 and 135·64 μl O2 gdfw−1 h−1, respectively. This was calculated to be equivalent to a metabolic rate of 0·648 J individual−1 24 h−1 for N. nitidosa and 1·752 J individual−1 24 h−1 for N. nucleus. Estimation of the production of N. nucleus, from its respiration rate, revealed that for comparable populations, N. nucleus was approximately a third more productive than N. nitidosa, 30 kJ g dry flesh weight (dfw)−1 m−2 y−1 as opposed to 20 kJ gdfw−1 m−2 y−1. Examination of the Kleiber's constant (β) obtained for each species, demonstrated that for N. nitidosa β fell in the range 0·75–1 and that for N. nucleus β fell in the range 1–1·25. This suggests, in combination with other data, that N. nucleus adopts an ‘exploitative’ functional strategy as opposed to N. nitidosa, which can be regarded as adopting a ‘conservationist’ functional strategy.

Observations on the hypoxic tolerance of both N. nitidosa and N. nucleus revealed that N. nucleus had a hypoxic tolerance about twice that of N. nucleus. The mean survival time±standard error for N. nitidosa was 3·53±0·18 d in contrast to 7·72±0·21 d for N. nitidosa. The hypoxic tolerance of either species was not related to body size and was independent of any possible effects of starvation. These results are discussed with reference to their potential effects to determine the distribution of N. nitidosa and N. nucleus.

The small free-swimming scallops, Chlamys hastata and Chlamys rubida, are frequently encrusted by the sponges Mycale adhaerens and Myxilla incrustans. It is unclear why this association exists. We hypothesized that living on scallop valves increases sponge survival by reducing the effects of sediment accumulation. Scallops were collected to measure correlations between sediment load and encrusting sponge mass. In the laboratory, the survival of sponges on living scallops and empty scallop valves was measured. Time-lapse video was used to quantify spontaneous swimming and clapping of C. hastata. In the field, both scallop size and sponge mass were significantly greater in high turbidity sites. In the laboratory, sponges on empty scallop valves experienced near complete mortality after five weeks. Manually clearing sediments increased survival but did not duplicate the high survival of sponges on living scallops, which regularly swam or clapped their valves.

Three species belonging to the genus Zanclea: Zanclea divergens, Zanclea tipis, sp. nov. and Zanclea exposita, sp. nov. have been described as epizoic of bryozoan from the coral reef of the Bunaken Marine Park (Sulawesi Sea, Indonesia). The record of Z. divergens is the second after its description from Papua New Guinea. Zanclea tipis is characterized by a polymorphic colony and a medusa with very extended exumbrellar pouches. Zanclea exposita shows a naked hydrorhiza creeping on the surface of the bryozoan skeleton.

An evolutionary trend among the Zancleidae, from species epibionts of algae and bivalve shells with the hydrorhiza covered by perisarc to species symbiotic with bryozoan with a naked hydrorhiza, is discussed.

Stomatolepas elegans on a Dermochelys coriacea is reported at Seiland, Finnmark, northern Norway at the highest latitude recorded for this species or for any members of its subfamily (Platylepadidae), as well as for its turtle host. The distribution of the species of Stomatolepas is given and their taxonomy is briefly discussed. A recording of data on the different species of Stomatolepas gives the distribution on the host as well as the identity and the collecting locality of the latter.

The tolerance of the European sea bass to high salinities was determined through abrupt and gradual transfers to different hyperosmotic media. Mortality rate reached roughly 50% in fish abruptly transferred to 70 psu salinity and in fish gradually adapted to 90 psu salinity. All fish abruptly transferred to 90 psu salinity expired in less than three hours. A crisis and regulation type osmoregulatory pattern, related to the range of the osmotic shock, was recorded following abrupt transfers to the tolerable experimental media. The lethal level of blood osmolality in sea bass was determined.

We summarize all the data of nest placement, incubation period, emergence of hatchlings and nest study of the first reported nesting event of a loggerhead turtle Caretta caretta (Reptilia: Cheloniidae) in the Spanish Mediterranean coast. The nest was laid in a beach of Almería province (south-east Spain) in July 2001. The incubation period was 58 days. Forty-two hatchlings emerged from a total of 97 eggs laid. Future beach surveys will determine whether this is a sporadic nesting event or whether loggerheads nest frequently in these coasts.

This study focused on the breeding period of Stenorhynchus seticornis (Brachyura, Majidae, Inachinae) in the south-eastern Brazilian coast. Monthly collections were accomplished from January to December of 2000. A catch effort of approximately 4 h was allocated to each monthly survey. The breeding intensity was determined as the percentage of ovigerous crabs within the whole adult female population. A total of 204 adult females were obtained, from which 74·5% presented eggs attached to their pleopods. Ovigerous females were observed year-round, usually comprising more than 60% of sampled adult females. The ovigerous frequency was not found to be correlated with either temperature or salinity.

The present study demonstrated histochemically that the enzyme activity was present in the cerebral vesicle, epidermis, muscles, endostyle and anus of amphioxus Branchiostoma belcheri tsingtaunese. This is the first noted report on localization of constitutive nitric oxide synthases in a celphalochordate.

Body volume was measured directly by the water displacement method and using three different geometric models, consisting of a series of cones and truncated cones, in California sea lion (Zalophus californianus) pups from the Gulf of California. Volume is required for the estimation of density, an indicator of the ratio of fat to lean mass. A model consisting of two cones and four truncated cones predicted body volume with greatest accuracy (volume=1·11+1·06&;estimated volume, r2=0·90, P<0·001, SEE=0·673, N=274). This model, however, was not adequate to estimate absolute pup body density (mass to volume ratio), as it yielded values poorly correlated with observed body density (r=0·14, P=0·02). However, the regression line of mass on volume indicated that density decreased with volume, so the mass to volume ratio is a biased estimate of density and is not appropriate for comparing whole body density among sea lion pups. The direct analysis of the relationship between body mass and body volume (observed or estimated) through analysis of covariance provided a better tool to compare the relative density among pups of different sex, populations, or born in different years. The results from such analyses are consistent with previous evidence of sex and age effects on body composition.

The analysis of remotely sensed altimeter data and in situ measurements shows that ERS 2 radar can monitor the ocean permanent thermocline from space. The remotely sensed sea level anomaly data account for ∼2/3 of the temperature variance or vertical displacement of isotherms at a depth of ∼550 m in the Subtropical North Atlantic Ocean near 32·5°N. This depth corresponds closely to the region of maximum temperature gradient in the permanent thermocline where near semi-annual internal vertical displacements reach 200 to 300 m. The gradient of the altimeter sea level anomaly data correlates well with measured ocean currents to a depth of 750 m. It is shown that observations from space can account for ∼3/4 of the variance of ocean currents measured in situ in the permanent thermocline over a 2-y period. The magnification of the permanent thermocline displacement with respect to the displacement of the sea surface was determined as −×650 and gives a measure of the ratio of barotropic to baroclinic decay scale of geostrophic current with depth. The overall results are used to interpret an eight year altimeter data time series in the Subtropical North Atlantic at 32·5°N which shows a dominant wave or eddy period near 200 days, rather than semi-annual and increases in energy propagating westward in 1995 (west of 25°W). The effects of rapid North Atlantic Oscillation climate change on ocean circulation are discussed. The altimeter data for the Atlantic were Fourier analysed. It is shown how the annual and semi-annual components relate to the seasonal maximum cholorophyll-a SeaWiFS signal in tropical and equatorial regions due to the lifting of the thermocline caused by seasonally varying ocean currents forced by wind stress.

Infauna diversity is reported from the Sabellaria alveolata reefs in the bay of Mont Saint-Michel in France, known as the greatest European reef formation. Polychaetes dominate the fauna, but other species also play a role in terms of reef functioning. Species richness of the associated infauna is much higher than that of the surrounding sediments and is concentrated mainly on the reef surface. Species richness clearly varied according to the three stages of reef evolution: the ‘degraded’ reef stage is different from the ‘ball-shaped structure’ and ‘platform’ stages. Multivariate analyses indicate that three species communities can be distinguished, each corresponding to a different stage of reef development. The number of species is very high, but only a few species are restricted to a particular reef stage. Variations of surface topography and spatial heterogeneity can explain unusual associations of species that make infauna associated with S. alveolata reefs very unique.

Moreover, the high densities of S. alveolata (up to 60,000 ind m−2) raise questions regarding the role of the reefs in the ecosystem of the bay. Anthropogenic influences, notably mechanical disturbances due to fishing activity, show a steady increase and may have a serious impact on the assemblage diversity and the ecological stability of the reef, even though recolonization of S.alveolata is possible in degraded reef areas. An important question that must be addressed is whether human activities could influence the role of S. alveolata reefs in the bay of Mont Saint-Michel.

The specimens of Melibe fimbriata were found during October 2001 in Stari Grad Bay (Island of Hvar, Croatia) in Cymodocea nodosa and Posidonia oceanica beds on sandy and sandy–muddy bottoms at depths of 2 to 15 m. Presently, this is the northernmost record of this lessepsian immigrant in the Mediterranean basin.

Published and unpublished records of epipelagic calycophoran siphonophores from around southern Africa were examined for zoogeographic structure. There is a close match between prevailing patterns of surface ocean circulation and zoogeography, which while similar to previous studies of intertidal taxa and euphausiids, is different from them in some key details. Separate subtropical provinces are associated with both the Angola and Agulhas Currents, and the latter system has a marked influence on the composition of (warm-temperate) assemblages along the south coast of South Africa. The nearshore waters in the Benguela upwelling ecosystem (cold temperate) are distinct, but the Lüderitz upwelling cell does not appear to act as an internal boundary within the Benguela ecosystem, as has been previously noted for benthic communities. Species richness is greater in oceanic than coastal waters, and peaks in subtropical waters. High diversity is also noted offshore in the area between Capes Agulhas and Columbine, where water of Indian, Southern and Atlantic Ocean interact. Indicator species for each major water mass were tentatively identified.

Both the salmon louse Lepeophtheirus salmonis and its close relative Caligus elongatus are ectoparasitic on Salmonidae in salt water in the northern hemisphere. In this study we monitored population dynamics of these parasites on anadromous brown trout, i.e. sea trout, on the Norwegian Skagerrak coast in the winters of 1998–1999 and 1999–2000. The low salinity was expected to reduce sea lice populations as lice do not tolerate sojourns of more than a few weeks, at most, in freshwater. Results confirmed the presence of both parasite species on estuarine sea trout in winter, and showed that the lice populations go through a bottleneck in this period. Prevalences of infection of both parasite species were very different in the two sampling periods, but fell below 10% in March in both winters. Median infection intensity was 1–2 fish−1. Salinity was statistically related to the presence of C. elongatus both winters, and to L. salmonis in 1999–2000. Temperature appeared to be less important for the abundance of lice.

The short-term response of Mediterranean upper infralittoral macroalgal species to experimental human trampling was investigated. Disturbances of six different intensities were applied within the integral reserve of the Ustica Island marine protected area (Italy, Mediterranean Sea). The dominant macroalgal species Cystoseira brachicarpa v. balearica and Dictyota mediterranea were strongly affected by human trampling. Higher levels of disturbance significantly affected both algal percentage cover and canopy at an increasing rate. Three months after trampling, for both variables it was highlighted that the algal recovery from disturbance was incomplete, being significantly different among trampling intensities. The current study revealed that in the short-term it was not possible to identify critical levels of trampling that are sustainable for this shallow community.

Most krill species undergo diel vertical migration (DVM) which is to some extent influenced by light intensity. During a solar eclipse (11 August 1999) the upward and downward movement of krill, Meganyctiphanes norvegica, inhabiting a Swedish fjord followed closely changes in light intensity. Here the eclipse was partial (77%) and the weather overcast and yet krill at 70–90 m depth were able to detect, and respond to very small changes in light. This observation of an event during mid-day which is not pre-programmed confirms light as an important triggering mechanism for krill DVM.

The spectral sensitivities of five species of decapod crustaceans have been determined by electroretinogram measurements. Their spectral sensitivities conform to the general picture for marine crustacea with high sensitivity to blue-green wavelengths and some showing sensitivity to violet/near ultraviolet. Two deep-water species (Paromola cuvieri and Chaceon (Geryon) affinis) have spectral sensitivity maxima below 500 nm, whereas the three coastal species examined (Crangonallmani, Pandalus montagui and Nephrops norvegicus) are maximally sensitive to light of longer wavelengths (510 to 525 nm).

The abundance of Calanus finmarchicus is known to have fallen between the present and the late 1950s in north-eastern Atlantic shelf waters. Further west in deeper water, however, long-term abundance of the copepod has risen.