The fecundity of Liocarcinus depurator (Decapoda: Brachyura) in the Ría de Arousa (Galicia, north-west Spain) and the reasons why it fluctuates were analysed, comparing the results with data available from other geographical areas. The incubation of L. depurator eggs in the Ría de Arousa generally takes place between January and September, although ovigerous females can be found all year round. The number of eggs per brood in L. depurator varied considerably in the Ría de Arousa and ranged from 5265 (carapace width (CW=31·3 mm, stage III) to 203,724 (CW=44·6 mm, stage I). The allometric equations adjusted to fit each egg development stage indicated that there was a strong positive correlation between female body size and the number of eggs the animal is able to bear. Female body size, measured as the carapace width, was the main factor causing variability in the fecundity of L. depurator. The second most important cause of variability in the development stages of the eggs was the number of eggs per brood, which may be due to the gradual loss of eggs that occurred during the incubation of these eggs in the female abdomen. Temporal changes constituted another significant factor in the variability of the fecundity of L. depurator. The allometric equations (log F=log a+b×log CW) fitted to each month and development stage I presented changes in the slope which point to the existence of a temporal evolution in the number of eggs. In the Ría de Arousa and for all the development stages, L. depurator was found to have a significant negative correlation between the number of eggs per clutch and egg volume. Egg volume also correlated negatively with the size of the female in stages I of the egg development. The degree of correlation between the volume and number of eggs was greater than the correlation between volume and size. The main cause of the variability in the egg volume of L. depurator in the Ría de Arousa may be attributed to the development stage (ANCOVA, P<0·001).

Infection of Nephrops norvegicus by a dinoflagellate parasite belonging to the genus Hematodinium, is reported in populations of Nephrops from the Irish Sea. Diseased animals are recognized by an opaque vivid body colour and high densities of parasites in the haemolymph. Infection causes a general morbidity of the host along with a reduction in swimming performance, which eventually leads to the death of the host lobster. Research vessel cruises performed over the period 1994–2001 have shown Hematodinium to occur in populations of Nephrops from the Irish Sea throughout this period. High infection prevalence during the month of April and negligible levels during October agree with published data on seasonal infection levels in Scottish Nephrops stocks. Data on spatial and temporal infection prevalence are presented for the first time for the Irish Sea and show variation between stations and between years. Mean infection prevalence peaked at 18% of captured Nephrops during April 1996 and was followed by a downward trend to 2001. Infection predominates in small Nephrops (<30 mm carapace length) and in females is normally associated with immature animals. Although a positive correlation with seawater salinity was noted, preliminary analysis did not show a relationship between prevalence and other environmental factors.

Adult Nassarius reticulatus were exposed for two to three months to dissolved tributyltin (TBT), dibutyltin (DBT), triphenyltin (TPT) and diphenyltin (DPT) chlorides and to copper sulphate (CuSO4) in order to study the effectiveness of these compounds to induce imposex (penis and vas deferens development). The dialkyltins and copper did not promote imposex under exposure to 500 ng Sn l−1 and 500 ng Cu l−1. However, dissolved nominal concentrations varying between 100 and 500 ng Sn l−1 of TBT or TPT induced imposex in, respectively, 22 to 43% and 24 to 44% of the females. The testosterone titres of females increased significantly after two months' exposure to 250 ng Sn l−1 of TPT and TBT and the same happened to males exposed to 100 and 250 ng TPT-Sn l−1 and to 250 ng TBT-Sn l−1.

Various indices related to reproduction and the fecundity of Helicolenus dactylopterus dactylopterus (Teleostei: Scorpaenidae) were analysed. Sexual dimorphism does not occur in the population we studied and the sex ratio is always equal. The size of the species at sexual maturity is a standard length of 130 mm for males and 145 mm for females. The maximum gonadosomatic index values for males and females are temporally out of phase to a large degree, which explains the intra-ovarian storage of spermatozoa that occurs in this species. There are large hepatic reserves which are basically used in the synthesis of vitellogenin, while the mesentery fat reserves are not mobilized until the end of the maturation process of the oocytes. Multiple spawning takes place between January and February, consisting of between 11,000 and 87,000 eggs, of about 500 μm in diameter. The fecundity of the species is, with a high degree of correlation, determined by the size and weight of the individuals.

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.

Spatio–temporal changes in density, breeding cycle, growth and population structure of Hydrobia ulvae (Gastropoda: Prosobranchia) were studied by monthly sampling of a wide bare mudflat in Marennes-Oléron Bay. Four stations, located along a cross-shore transect and characterized by different geomorphological structures, were investigated from March 2000 to February 2001. Hydrobia ulvae was mainly distributed in the upper half part of the mudflat and no individuals were found in the lower part. The breeding cycle extended from March to December and showed two annual peaks, in spring and in autumn. Three cohorts were recruited during the year and showed high growth rates during summer; the parameters of the von Bertalanffy model describing the growth curves were equal to kmax=0·47±0·5 mm month−1 and L∞=5·4±0·2 mm. The snail population had similar size–frequency structure along the transect at the beginning of the survey but summer recruitment initiated spatial differentiation. Reproduction occurred in the middle part of the mudflat but recruits mainly settled down at the upper level of the mudflat; new cohorts appeared with increasing individual densities. The middle part of the mudflat was rather dominated by adult individuals which showed large density fluctuations.

Mytilus edulis, Cerastoderma edule and Aequipecten opercularis were found to ingest zooplankton when suspended in mesh cages in the water column in the Firth of Clyde. Zooplankters were also found in the stomachs of bivalves that had been taken directly from their natural habitat. The bivalves consumed a wide range of zooplankton species, but selectively consumed smaller categories of zooplankton present. Condition of zooplankton in the stomachs of the bivalves varied with zooplankton species. A degree of larviphagy was evident, particularly in Mytilus edulis.

Sub-lethal exposure of the marine amphipod Gammarus locusta to a range of copper concentrations (Cu) in water and spiked sediments were performed, and the resulting bioaccumulation of Cu into intracellular granules investigated. The presence of Cu-granules was demonstrated histochemically by the rubeanic acid method. The granules were quantified by automated image analyses (expressed as volume fraction, VV). The metal composition of the granules was characterized by X-ray microprobe analysis. The results showed that granules, rich in copper and sulphur, were formed in response to Cu exposure in water and sediment. These granules appeared in the B-cells of the hepatopancreas. VV values increased over the dose-range of Cu compared with control in water (P<0·001) and sediment (P<0·01) exposures. The abundance of the granules also increased with increasing whole-body Cu content, suggesting that at least part of the increasing Cu level was incorporated into the granules, as a strategy for Cu detoxification along with normal storage of Cu during the moult cycle. The presence of sulphur within the granules is thought to represent an organic detoxification mechanism for Cu. The formation of Cu-granules as a cellular response is a useful biomarker of Cu-exposure in ecotoxicological studies with amphipods. The rubeanic acid method is a useful screening tool for this copper.

The reproductive cycle of Bolinus brandaris (Gastropoda: Muricidae) was investigated. Specimens were sampled monthly from a site off Sant Carles de la Ràpita, in the western Mediterranean, between February 1999 and March 2000. A pattern was observed in the reproductive cycle, with two reproductive peaks (April and June–July). The first stages of gametogenesis began in September for males and November for females. Mature males were found from December to April and from June to July. Maximum ripening in females was attained at the end of June and during July, coinciding with the spawning season. In May, there was a resting stage in females, and for both sexes from August to October.

Males exhibited variation in penis length and vas deferens width related to the reproductive cycle. Sizes of both dimensions increased as maturation progressed. The variation was not found in imposex females.

Laboratory assessment of barnacle cyprid settlement showed that it was increased by a multiple of ∼6 and by a multiple of ∼3 by the pedal mucus produced by Patella vulgata and by Littorina littorea, respectively. Field experiments showed that pedal mucus produced by P. vulgata could increase cyprid settlement by a multiple of ∼4, but that there was no effect of the pedal mucus produced by L. littorea. Evaluation of the effect of pedal mucus coated with nitro-cellulose and various pedal extracts, on cyprid settlement, ascertained that there appeared to be no chemotactic or chemotaxic effect of pedal mucus on cyprid settlement. In contrast, the use of a physical analogue to pedal mucus, silicon grease, increased cyprid settlement by a multiple of ∼18.  Pedal mucus produced by P. vulgata and by L. littorea increased the time spent by cyprids in surface suitability testing by a multiple of ∼10 and ∼3, respectively. Only the pedal mucus produced by P. vulgata had any effect on the exploratory behaviour of cyprids increasing the time spent on this behaviour by a multiple of ∼3. Pedal mucus affects the settlement of cyprids through adhesive enmeshment, resulting in positive feedback to the mechanoreceptors housed in the antennules of cyprids, in what is effectively a settlement cascade. Pedal mucus produced by P. vulgata and L. littorea can affect the settlement of the majority of settling marine organisms through physical entrapment. Pedal mucus produced by L. littorea will have little, if any, effect on the settlement of organisms in the field whereas the pedal mucus produced by P. vulgata may be of major importance in determining the adult distribution patterns.

Settlement of Concholepas concholepas (Gastropoda: Muricidae) on natural and artificial substrata was studied between April 1999 and March 2001 at two sites in central Chile; the Las Cruces Marine Reserve and El Quisco Management and Exploited Area. Four different artificial materials were tested in the low intertidal zone during 1999 settlement season to determine their properties as settlement and microhabitat substrata for competent Concholepas larvae. Globular pads made of plastic filaments were identified as the best artificial collectors, exhibiting overall higher settlement rates than rock plots and lower variability among replicates within a given site. Thus, subsequent monitoring of settlement used only these globular pads that were replaced twice monthly. The temporal pattern of settlement was remarkably similar from year to year, starting at the end of austral winter (August–September) and ending in summer (December–January), defining a temporally restricted settlement season. Settlement at two sites within the Marine Reserve of Las Cruces was significantly higher than at sites in El Quisco. However, during the second settlement season, an additional site at El Quisco exhibited settlement rates comparable to those observed at Las Cruces. The results show that Concholepas settlement varies significantly over scales of several hundreds of metres as well as tens of kilometres, probably due to differences in coastal oceanographic conditions.

The control region of the mitochondrial genome was amplified and sequenced for six individuals of the gobioid fish Pomatoschistus minutus, from several European localities, and one specimen of the related Deltentosteus quadrimaculatus. The length of this region for the former species was found to be 773 bp, 7·1% shorter than that previously described as the most compact D-loop known among teleosts. Sequences from other fish have been compared and the largest gap falls in the section between the conserved sequence block and the pyrimidine tract. Alignment of P. minutus sequences was done with D. quadrimaculatus, whose control region length was 853 bp, and this gap was found to be of 61 bp. For the P. minutus sample, the intraspecific sequence divergence is 0·07%.

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.

Surface characteristics including wettability, thickness and adhesive potential of the pedal mucus produced by Patella vulgata and Littorina littorea were measured, to determine their effects on the settlement of marine organisms. The pedal mucus produced by P. vulgata was less wettable than that produced by L. littorea. For organisms that prefer to settle on hydrophobic substrata the pedal mucus produced by P. vulgata would be their preferred settlement site. The pedal mucus produced by stationary P. vulgata was thicker (mean thickness±SE=0·37±0·004 mm) than the pedal mucus produced by mobile P. vulgata and/or that produced by L. littorea, neither of which differed in their thickness (mean thickness±SE =0·10±0·01 mm).  The pedal mucus produced by P. vulgata had a greater adhesive potential (mean force of adhesion for the size range of mimics examined=3715–5380 Nm2) than the pedal mucus produced by L. littorea (mean force of adhesion for the size range of mimics examined=2846–3361 Nm2). Comparison of the adhesive potential of the pedal mucuses with a pedal mucus analogue, silicon grease, suggests that the pedal mucuses function as a Stefan (1874) adhesive when adhering organisms.

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).

Semele solida and Tagelus (Tagelus) dombeii are two tellinacean bivalves which coexist in the lower intertidal zone of a sandflat in south-central Chile but follow different feeding strategies. Wheras T. (T.) dombeii is a suspension-feeder, S. solida is a facultative deposit-feeder. In this study, digestive gland indices and reproductive cycles were described in relation to annual food availability and related to their feeding modes. Results showed that gonadic index cycles were similar for both species, with highest values being observed during the spring when water temperature was still on the rise and microflagellate and centric diatom density was at its peak. However, histological analyses indicated that the spawning period of T. (T.) dombeii extended from November 1995 to March 1996 and from August 1996 to January 1997, whereas S. solida presented a continuous spawning period that extended from September 1995 to December 1996. Results suggest that extended spawning throughout the winter by S. solida is a consequence of its ability to feed on bottom deposits when food in suspension is low.

The relationship between shell growth rate and striae deposition was investigated in a field study in which groups of juvenile scallops, Pecten maximus, (Pectinidae: Bivalvia) were deployed for monthly periods over a year in the Menai Strait (North Wales). The number of striae deposited per day, inter-striae width (the increment of shell deposited between successive striae) and striae abundance (the number of striae deposited per mm of shell height) all correlated well with measured shell growth rates. During the winter months, when seawater temperatures were minimal (6°C), inter-striae width declined, whilst striae abundance increased, whereas during the summer when seawater temperatures were maximal (18°C), shell growth was rapid with maximum inter-striae width, resulting in a seasonal pattern of narrowly grouped, then widely spaced striae. This seasonal pattern in inter-striae width variation provides an accurate and reliable method for estimating the number of growth cycles and hence the age of P. maximus.

Death assemblages found in the Augusta Roadstead harbour (Mediterranean Sea) reflected some modifications in benthic environment that occurred since the 1960s, when the construction of dams closed the commercial harbour. In particular, evidence of a drop in the hydrodynamic levels were found, together with a mud sedimentation increasing. Furthermore, a turbidity phase characterized by a dominant Corbula gibba was identified as due to extensive dredging. Such temporary communities, distributed in accordance to the degree of instability and pollution, preceded the present day, very poor and destructured benthic assemblages.

A new species of the genus Caprella (Crustacea: Amphipoda: Caprellidea) is described based on the specimens collected from the Strait of Gibraltar, southern Spain. The new species, Caprella caulerpensis, was found living in mud bottoms with the seaweed Caulerpa prolifera (Forskål) Lamouroux. Caprella caulerpensis can be distinguished from the most related species, Caprella rapax, mainly by the number of articles in the flagellum of antenna 1, the morphology of the dactylus of gnathopod 2 and the pereonites length.

The exposure to discharging nematocysts of the eolid nudibranch Cratena peregrina feeding on polyps of the hydroid Eudendrium racemosum was examined. The smaller size-class of microbasic eurytele mastigophor nematocysts is located on the tentacles of the hydroid polyps, while the larger size-class of holotrichous isorhiza nematocysts is located on long cnidophores and basal rings of some polyps. Discharging nematocysts of the tentacles do not appear to have damaging effects on the dorsal appendages of the snail, the cerata. In contrast, contact of a cnidophore with a ceras elicits massive discharge of nematocysts, which results in adherence, membranolysis and local destruction of the epidermis within seconds. The differential locations and effects indicate that the small tentacle nematocysts serve for capturing prey, while the large cnidophore nematocysts serve for the hydroid's defence. Both small and large, discharged and intact nematocysts were found in the pharynx and stomach of the snail after feeding. Thus, the alimentary tract appears to be efficiently protected against discharging nematocysts. Small and large intact nematocysts, which were capable of discharge, were also found in the cnidosacs.