Microbial enzyme activities in the upwelling system of Messina Straits: dynamics and biogeochemical considerations.

From June 2003 to March 2004, three extracellualr enzymes (Leucine aminopeptidase, Beta glucosidase, Alkaline phosphatase) and the abundance of culturable heterotrophic bacteria were determined in three coastal sites (Scaletta, Guardia and Pellaro) on the Sicilian and Calabrian sides. Samplings were performed at surface, and above, within and below the Deep Chlorophyll Maximum (DCM) layer. The temporal evolution of these microbial activities involved in Carbon and Phosphorus cycles was investigated; particularly, changes in microbial decomposition of proteins, polysaccharides and organic phosphates were related to the main environmental variables (temperature, salinity, nutrients, chlorophyll-a) and to the hydrodynamic regimen.