Pelagic production and biomass in the Adriatic Sea
Serena Fonda Umani

On the basis of the available data on plankton production and biomass in the Adriatic Sea, three different areas may be delineated: a - Open waters of the central and southern Adriatic, characterized by an “oceanic” community. Primary production rates are low. Microphytoplankton and especially diatoms are abundant; microzooplankton is dominated by tintinnids; herbivorous copepods are dominant throughout the year and carnivorous species are also important. The plankton communities show high diversity and great stability. A “top down” control appeared to regulate the energy fluxes. b - Open waters of the northern basin, characterized by neritic associations with moderate primary production rates and biomass. The species originating from the southern Adriatic and the Mediterranean are present throughout the year. A marked west-to-east gradient of production and biomass is present during the stratified period. The models of phytoplankton control appear to shift from “bottom up” to “top down” control, following the western-eastern gradient and changing seasonally. c - A coastal zone characterized by a neritic community of low diversity and high primary production and biomass. Nanoplankton primary production generally prevails. This production appear to be used mainly by ciliates other than tintinnids during the stratified period. Nanoplankton also represents an important food source for the abundant filter feeders. During the persistence of the frontal system, separating coastal from off shore waters, terrigenous inputs stimulate high primary production which is confined to inshore areas. Zooplankton grazing is not sufficient to control the produced biomass and transfer to offshore is restricted, resulting in eutrophication

Keywords: Primary production, plankton biomass and distribution, Adriatic Sea.
Contents of this volume Sci. Mar. 60(Suppl.2) : 65-77 Back PDF
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