Considerations on the effects of trophic status on microcystin production and the dominance of cyanobacteria in the phytoplankton assemblage of Mediterranean reservoirs (Sardinia, Italy)
Presentano: Maria Antonietta Mariani, Antonella Lugliè, Bachisio Mario Padedda
Results of a research on the relationship between Cyanobacteria, cyanotoxins and environmental conditions in Sardinia will be presented. Evidence for increasing levels of eutrophication and abundance of cyanobacteria suggest that climate climate change may have a strong impact, especially in the southern Mediterranean Region, Monthly samples were collected in four reservoirs (Bidighinzu, Pattada, Sos Canales and Torrei), characterized by different trophic status, from June 2010 to December 2011. Analysis of similarity indicated that cyanobacteria abundance and species composition differed significantly among the reservoirs. Redundancy analysis highlighted relationship between cyanobacteria abundance and trophy, and with hydrological and seasonal patterns. Spearman's analysis highlighted significant correlations among the most important species (Planktothrix agardhii–rubescens group, Aphanizomenon flos-aquae and Dolichospermum planctonicum), algal nutrients and microcystins concentration. Species composition during periods of maximum microcystin concentrations differed from those typical of Mediterranean sites. New potential microcystin producers were also identified (Aphanizomenon klebahnii, Dolichospermum macrosporum and Dolichospermum viguieri), highlighting a high diversity of cyanobacteria in the Mediterranean area and a need for detailed, long-term, research at a local scale.
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