In the Mediterranean region, reservoirs represent the main sources of water supply for various human demands. The main issues in these ecosystems are linked to eutrophication and, consequently, to the development of Cyanobacteria blooms. However, freshwater red tides caused by dinoflagellates are becoming a new emergent problem for water treatments. In Sardinian reservoirs, dinoflagellate blooms have been detected since the seventies and were mainly caused by Ceratium hirundinella. Recently, other dinoflagellates have given rise to similar events. One of the most intense was recorded in Cedrino Lake in February 2012. The causative dinoflagellates were firstly recognized as Peridinium species. In this study, fixed samples collected during this event were analyzed in more detail with optical and scanning electron microscopy. Surface sediment samples were taken and analyzed for the presence of resting cysts. Genetic analyses were conducted on alive and fixed vegetative cells. Furthermore, ecological data were analysed. The plate formula of the recovered cells was po, x, 4’, 6’’, 5C, 4S, 5’’’ and 2’’’’. Scattered pores ornamented the theca and numerous spines the hypotheca, but cells without spines have been observed. The cysts were slightly irregular in shape, and most of them maintained the external theca. The cyst content was grainy with yellowish to reddish accumulation bodies. Based on the tabulation features, this d i n o f l a g e l la t e w a s a s s i g n e d t o t h e P e r i d in i o p s i s g e n u s , ‘penardii’ section. The genetic results showed a very high similarity of the Sardinian sequences with Peridiniopsis penardii sequences from China. The species was recorded in Cedrino Lake in a wide time frame (September to June), but the two bloom events showed a well-defined seasonality (February-March). The species abundances were significantly correlated with a number of environmental parameters (e.g. temperature and nutrients).
First detection of the bloom forming Peridiniopsis penardii from a Sardinian reservoir (NW Mediterraean Sea) / Satta, Cecilia Teodora; Stacca, D; Lai, Gg; Mariani, Ma; Padedda, Bachisio Mario; Sechi, Nicola; Buscarinu, P; Lugliè, Antonella Gesuina Laura. - (2015), pp. 68-68. ((Intervento presentato al convegno XXII Congresso AIOL Associazione Italiana di Oceanologia e Limnologia tenutosi a Verbania Pallanza nel 28 settembre - 1 ottobre 2015.