LARVAL EXCHANGE AND DISPERSION OF POLYCHAETES BETWEEN A BAY AND THE OCEAN

A dynamic meroplanktonic study of the Bay of Arcachon (France) and the nearby continental shelf has been undertaken to examine the degree of larval exchange between the two ecosystems. Arcachon Bay is a bight connected via a narrow strait to the ocean, especially rich in invertebrate communities and more particularly polychaetes (>200 species have been indexed). The exchange of water masses between the oceanic system and the coastal lagoon is the consequence of strong tidal currents. Several well-represented species of larval polychaete populations were used as an index of communication (larval flow) between these systems, and allowed testing of whether one of the ecosystems is beneficial to the other. This study tends to demonstrate that the theory of a larval dispersion favoured by pelagic life is not necessarily verified. © 1990 Oxford University Press.