MEPS 133:57-71 (1996)  -  doi:10.3354/meps133057

Structure and functioning of the anthropogenically transformed Comacchio lagoonal ecosystem (Ferrara, Italy)

Sorokin YuI, Sorokin PYu, Gnes A

Since 1985, the lagoons of Comacchio, in the coastal area of the NW Adriatic Sea, have been experiencing an ecological catastrophe caused by an extremely dense bloom of picocyanobacteria. The bloom has resulted in a drastic depletion of all kinds of zooplankton, including protozoa. It has caused mass mortality of benthic fauna and the collapse of valuable eel and mullet fisheries. The ecosystem of these lagoons, being thus completely transformed and deprived of animal components of its food web, appears to be remarkably stable on annual and seasonal scales. Its main functional component is the phytoplankton community dominated by several species of picocyanobacteria of the genera Coelosphaerium, Aphanothece and Synechococcus. In this paper quantifications of the main components of the plankton are presented together with data on standing stocks of organic matter and its cycling, and on the cycling of phosphorus and sulfur. The energy balances of the ecosystem are calculated and energy flow schemes derived. The mechanism of the extreme stability of this new kind of aquatic ecosystem and a probable scenario of its origin are discussed.

Lagoonal ecology . Aquaculture . Cyanobacteria . Eutrophication . Microplankton

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