SPATIOTEMPORAL VARIATIONS IN MEGABENTHOS ABUNDANCE IN 3 DIFFERENT HABITATS OF THE CATALAN DEEP-SEA (WESTERN MEDITERRANEAN)

The spatio-temporal variations in the megafauna (fishes, crustaceans, and other invertebrates) in three different habitats on the slope in t he Western Mediterranean (Catalan coast off Barcelona) have been inves tigated. Samples were collected at two fixed stations during 1991 and 1992, one inside and one outside a submarine canyon (at depths between 450 and 600 m) and additional samples were collected at another stati on on the lower slope (at a depth of 1200 m) in each season of the yea r. Three replicates of each sample were taken at each station. Differe nces observed between habitats, seasons, and zoological groupings were verified statistically by factorial ANOVA. The habitat appeared to be the main factor responsible for the differences observed in biomass a nd abundance values for the zoological groupings considered. Decapod c rustacean biomass was higher in the submarine canyon than in neighbour ing zones, and smaller species and juveniles were more abundant inside the canyon in the case of both fishes and crustaceans. Fish biomass w as most abundant in the lower slope. Seasonality was also a factor, al though to a lesser extent. Seasonal variations in biomass, especially fish biomass, were recorded in the deepest zone (1200 m). Crustaceans displayed lower sensitivity to seasonal factors, whereas other inverte brates did not, on the whole, exhibit seasonal variations.