No abstract

Marine macroalgae harbour abundant and diverse assemblages of epifauna. Patterns of distribution and abundance of epifauna, which are often variable in space and time, differ markedly among macroalgae species. Non-indigenous seaweeds may alter composition and structure of epifaunal assemblages and therefore harbour different assemblages from those associated with native macroalgae. In this study, we analysed the epifaunal assemblages associated with the native algae Bifurcaria bifurcata and the invasive alga Sargassum muticum on the southern part of the Galician coast (north-west Spain). In particular, we tested the hypothesis that there were differences in the epifaunal assemblages associated with the native and invasive algae. We used a hierarchical spatial sampling design to identify if these differences were consistent over space and time. Results indicated that there were significant differences between epifaunal assemblages associated with both algae. The fact that such differences were, in general, consistent at different spatial scales suggests that biological factors related to the specific habitat might play a more important role than physical factors as determinants of epifaunal distribution. This study also showed that S. muticum seems to supply a new and additional habitat for the native epifauna, contributing to increases in the spatial and temporal variability of epifaunal assemblages.

Macrobenthic assemblages were investigated at 26 stations located around Livingston Island, Deception Island and the Bransfield Strait at depths ranging from 42 to 671 m. Representatives of 30 major taxa were found. The maximal density was 5,260 specimens · m\ at Livingston Island; the mean abundance per station ranged from 160 to 4,380 specimens · m\. The total biomass of the macrozoobenthos declined with depth, with mean values of 3,201 g · m\ at shallower depths ( (100 m) and 210 g · m\ further down ( '100 m). After multivariate analysis (cluster analysis, MDS) based on Bray-Curtis dissimilarities, most stations could be assigned to one of three groups on the basis of distinct biomass differences between sites. The first cluster with a rich Ascidiacea biomass is common on shallower bottoms. The second, with Ophiuroidea as a characteristic group, is common on deeper bottoms. The absence of an 'indicator' taxon is characteristic of the remaining cluster of those stations with the lowest biomass values. No significant correlations were detected between macrobenthic biomass and any sediment parameters measured, probably because part of the benthos (i.e. the epifauna) could be better explained by the coupling with a highly productive water column. The role of the epi-infauna sensu Gallardo as the main factor structuring benthic assemblages in the investigated area is discussed.

This study aimed to determine the spawning strategy in the Atlantic bobtail squid Sepiola atlantica, in order to add new information to the knowledge of its reproductive strategy. A total of 12 females that spawned in aquaria were examined. Characteristics of the reproductive traits and egg clutches were similar to those of other known Sepiolidae. Clutch size varied from 31 up to 115 eggs. Females of this species had incorporated up to 1.58 times of their body weight into laid eggs. The size of laid eggs showed a positive correlation with maternal body size, supporting the idea that female size is a determinant of egg size. Our data suggest that S. atlantica is an intermittent terminal spawner, and that its spawning strategy comprises group-synchronous ovary maturation, multiple egg laying, and deposition of egg clutches in diVerent locations. The obtained data provide insights for future comparative studies on reproductive allocation.

A new species of sphaerodorid (Polychaeta: Sphaerodoridae), Sphaerodoropsisgarciaalvarezi sp. nov., is described from specimens collected on sandy bottoms off the Galician coast (Spain, north-east Atlantic). This species is characterized by having two pairs of digitiform lateral antennae, 13 dorsal macrotubercles per segment in mid-body setigers arranged in two transverse rows, five dorsal microtubercles per segment arranged in five longitudinal rows, six ventral papillae per segment arranged in six longitudinal rows, digitiform presetal lobes and ventral cirri, and composite setae with spinulation on blade and distal end of shaft. Complementary observations to original descriptions are also provided for closely related species Sphaerodoropsis bisphaeroserialis and Sphaerodoropsisarctowskyensis upon examination of type series.