Polychaete patterns from an oceanic island in the eastern Central Atlantic: La Gomera (Canary Archipelago)

The polychaete macrofauna along the shallow sublittoral of La Gomera (Canar y Islands, eastern Central Atlantic) was surveyed during the summer 1995 wi th a 0.01 m(2) van Veen grab. Sampling resulted in a moderate number of spe cimens per sample unit, which influenced the assessment of alpha and beta d iversity. Diversity patterns followed sediment and hydrographic gradients b etween the north of the island (coarse sandy bottoms directly exposed to th e open ocean), and the south (sheltered fine sandy bottoms). Of the 81 taxa recorded, two species were new to science, while a further 24 species were cited for the first time from the Canaries. Spionids (46% of faunal densit y), syllids (14 species) and onuphids were locally well represented and the ir distribution responded to life history features and sediment types. Poly chaetes with a wide biogeographic range and relying on meroplanktonic phase s, for dispersal, predominated. Factors controlling the access of polychaet e populations to oceanic islands are discussed, including the role of major surface oceanic currents in the dispersion of larvae and reproductive adap tations of species.