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RESEARCH PRODUCT

Driving factors of dinoflagellate cyst distribution in surface sediments of aMediterranean lagoon with limited access to the sea

subject

description

International audience; Seasonal distribution of dinoflagellate cysts were studied at five surface sediment study stations in Ghar El MelhLagoon (GML) (Tunisia) in relation to physicochemical parameters and phytoplankton abundance in the watercolumn. At least sixteen dinocyst types were identified, dominated mainly by Protoperidinium spp., Scrippsiellatrochoidea complex, Lingulodinum machaerophorum, Alexandrium spp. and Gymnodinium spp., along with manyround brown cysts. Cyst abundance ranged from 0 to 229 g−1 dry sediment. No significant differences in cyst distributionwere found among stations, though a significant variation was observed among seasons with cyst dominancein autumn. No significant variation was found between cyst abundance and the different abiotic factorsmonitored, neither in the water column (physicochemical parameters) nor in the sediment (% H2O). Low dinocystabundance was consistent with the dominance of non-cyst-forming dinoflagellates in the GML water column.