Spatial distribution of Chironomus salinarius Kieffer (Diptera: Chironomidae) in brackish water in Mediterranean area: First results

Coastallagoons are defined as open masses ofbrackish water isolated (or semi-isolated) from the sea by sand har, but receiving sea waters. They are characterised by a large environmental variability on spatial and temporal scales. Larvae o f Chironomidae are often numero us in brackish waters such as coastal lagoons; sometimes the adults can create swarms. The larvae usually have a clustered behaviour (ScHMID 1993), and their spatial distribution has to be considered at different scales and according to environmental variables. The chironomid distribution is usually linked to habitat characteristics like substratum or food avalibility, both in lotic and lentic habitats (ScHMID 1993, FRANQUET 1999, LüBINSKE et al. 2002, Vos et al. 2002). For the organisms living in soft sediments with high organic matter content, the oxygen concentration sould be considered (INTPANIS et al. 1996). Our aim was to provide an accurate knowledge of the larval spatial distribution in a French coastallagoon, related to environmental parameters.