Dinoflagellate cyst assemblages and harmful algal species from different transitional areas of the Western Mediterranean Sea

Abstract

The present study identified and quantified dinoflagellate resting cysts in sediment samples from transitional ecosystems in the Western Mediterranean Sea. The studied areas were two estuarine bays along the Catalan coast (Spain), and three lagoons along the western coast of Sardinia (Italy). Samplings were carried out from 2009 to 2011 at 5-11 sampling stations in the different sites. Germination experiments and genetic techniques were used to confirm species identification. Cyst assemblages showed high diversity, especially in the lagoons. However, the Peridiniales group dominated all the assemblages. Numerous species had not been recorded previously in the water column in their respective sites. Moreover, several species were detected for the first time in the Mediterranean Sea, including a new Scrippsiella species. Fourteen morphotypes belonged to potentially toxic or noxious species, with the genus Alexandrium dominating. Among the harmful species, a new Alexandrium cyst morphotype was described. Kryptoperidinium foliaceum cysts were first signalled in the Mediterranean Sea. Moreover, several species (e.g. Vulcanodinium rugosum, Gymnodinium litoralis and Alexandrium catenella) were detected for the first time in some of the sites. Detailed studies on cyst assemblages, combined with additional techniques, provided new valuable information on the dinoflagellate communities and, in particular, on harmful species