Fish mass mortality in the Etolikon Lagoon, Greece: the role of local geology

Leonardos I., Sinis A.I.

Date de parution: avril 1997
Volume: 21
Number: 2
Pagination: 201-206
Editeur: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/1997-212-006
Résumé

Mass mortalities of fish in the Etolikon lagoon have been observed sporadically. In the mass mortality which occurred in November 1990 it has been estimated that a large part of the fish stock was lost. As a result, fish catches were greatly reduced in the lagoon in the following years. Hydrobiological studies suggest that the deaths are due to the high concentration of H2S in the hypolimnion. The continual enrichment of the water with H2S is attributed to the presence of gypsum deposits in the drainage basin and to the anaerobic breakdown of the accumulated organic matter. The presence of H2S in combination with the physiography of the ecosystem, the influxes of fresh and salt water, the runoff of agricultural chemicals and the strong prevailing southerly winds are responsible for the observed phenomenon.

Mots-clés: Fish population - Greece - Lagoon - Mass mortality
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