The harmful dinoflagellate Prorocentrum minimum has different effects upon various species of grazing bivalves, and these effects also vary with life-history stage.Possible effects of this dinoflagellate upon mussels have not been reported; therefore, experiments exposing adult blue mussels, Mytilus edulis, to P. minimum were conducted. Mussels were exposed to cultures of toxic P. minimum or benign Rhodomonas sp. in glass aquaria. After a short period of acclimation, samples were collected on day 0 (before the exposure) and after 3, 6, and 9 days of continuousexposure experiment. Hemolymph was extracted for flow-cytometric analyses of hemocyte, immune-response functions, and soft tissues were excised for histopathology.Mussels responded to P. minimum exposure with diapedesis of hemocytes into the intestine, presumably to isolate P. minimum cells within the gut, thereby minimizing damage to other tissues. This immune response appeared to have been sustained throughout the 9-day exposure period, as circulating hemocytes retained hematological and functional properties. Bacteria proliferated in the intestines of the P. minimumexposed mussels. Hemocytes within the intestine appeared to be either overwhelmed by the large number of bacteria or fully occupied in the encapsulating response to P. minimum cells; when hemocytes reached the intestine lumina, they underwent apoptosis and bacterial degradation. This experiment demonstrated that M. edulis is affected by ingestion of toxic P. minimum; however, the specific responses observed in the blue mussel differed from those reported for other bivalve species. This finding highlights the need to study effects of HABs on different bivalve species, rather than inferring that results from one species reflect the exposure responses of all bivalves.

Large numbers of gelatinous zooplankton were collected off Mejillones Peninsula, Chile (Humboldt Current System) in January 1997 during an oceanographic cruise. The area was characterized by the mixing of 3 water masses and the development of coastal upwelling. Siphonophores were the predominant group at most of the stations and the calycophoran Bassia bassensis was overwhelmingly the most abundant species. Five group associations were distinguishable in relation to the water masses identified. Siphonophores were associated with Subtropical Surface Water, the ctenophore Pleurobrachia sp. with Subantarctic Water, the pelagic tunicate Salpa fusiformis with Equatorial Subsurface Water, an assemblage of all gelatinous groups with mixed waters, and a low occurrence of gelatinous groups with upwelled Equatorial Subsurface Water. Molluscs were the group least associated with any water mass. The potential percentage of small copepods removed by B. bassensis ranged between 2.9 and 69.3%. Our results indicate that B. bassensis was the most important secondary predator in the top 50 m of the water column, and could therefore have had a significant trophic impact on the population of small copepods off the Mejillones Peninsula during the sampling period, where small copepods constituted 80.6% of the total mesozooplankton community. This siphonophore potentially ingested an average of 17.3% of the total copepod biomass.

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.

The harmful dinoflagellate Prorocentrum minimum has different effects upon various species of grazing bivalves, and these effects also vary with life-history stage.Possible effects of this dinoflagellate upon mussels have not been reported; therefore, experiments exposing adult blue mussels, Mytilus edulis, to P. minimum were conducted. Mussels were exposed to cultures of toxic P. minimum or benign Rhodomonas sp. in glass aquaria. After a short period of acclimation, samples were collected on day 0 (before the exposure) and after 3, 6, and 9 days of continuousexposure experiment. Hemolymph was extracted for flow-cytometric analyses of hemocyte, immune-response functions, and soft tissues were excised for histopathology.Mussels responded to P. minimum exposure with diapedesis of hemocytes into the intestine, presumably to isolate P. minimum cells within the gut, thereby minimizing damage to other tissues. This immune response appeared to have been sustained throughout the 9-day exposure period, as circulating hemocytes retained hematological and functional properties. Bacteria proliferated in the intestines of the P. minimumexposed mussels. Hemocytes within the intestine appeared to be either overwhelmed by the large number of bacteria or fully occupied in the encapsulating response to P. minimum cells; when hemocytes reached the intestine lumina, they underwent apoptosis and bacterial degradation. This experiment demonstrated that M. edulis is affected by ingestion of toxic P. minimum; however, the specific responses observed in the blue mussel differed from those reported for other bivalve species. This finding highlights the need to study effects of HABs on different bivalve species, rather than inferring that results from one species reflect the exposure responses of all bivalves.

Menorca Channel (Balearic Islands, western Mediterranean) comprises 98,700 Ha of continental shelf. It has been proposed to include this area in the Natura 2000 network due to the wide range of species and habitats of high conservation value found here, such as Posidonia oceanica meadows and maërl and coralligenous beds. This study aimed to establish a scientific basis for managing and protecting the continental shelf bottoms in Menorca Channel. Sampling was carried out with side-scan sonar, beam trawls, box corers, a remote-operated vehicle and an underwater drop camera. The information collected was used to map the habitat distribution between 50 and 100 m depth, as well as make an inventory and describe the spatial patterns of both the specific and functional diversity. A total of 636 species was recorded in a mosaic of habitats in which Corallinacea calcareous algae and other soft red algae (Osmundaria volubilis and Peyssonnelia spp.) were the most abundant groups. Hotspots of specific and functional diversity were located in areas with high habitat heterogeneity and complexity. Protection of Menorca Channel should not only include the habitats and species in the European directives, but also the habitats that are not currently protected, such as O. volubilis and Peyssonnelia beds, due to Electronic supplementary material The online version of this article (

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The pattern of microgrowth bands in shell sections of the Mediterranean clam Chamelea gallina shows a seasonal variation in width. Widely spaced growth bands are formed in winter and late spring between January and June, whilst narrow growth increments are deposited in summer and early autumn between August and October, following the maximum summer seawater temperature. The warm summer seawater temperature of 33 "C in the western Mediterranean may be responsible for the suppression of shell growth, as evidenced both by the narrowing of the growth increments and by the later appearance of clefts in shell sections. There is no correlation between spawning and the formation of clefts in the shell of C. gallina. The annual pattern of narrow and wide growth increments has been used to estimate the age of C. gallina and to construct growth curves for this species from the eastern coast of Spain. Growth curves for the clams, determined from the internal microgrowth bands and from the spacing between the clefts in shell sections, differed from the curve calculated using surface growth rings.