Dinoflagellate cysts in recent sediments from Bahia Concepcion Gulf of California

The composition, abundance, and distribution of dinoflagellate resting cysts in recent sediments were analyzed at 12 sites in Bahfa Concepcion in the subtropical Gulf of California. Calcareous and organic Peridiniales, Gonyaulacales, and Gymnodiniales were identified at species level (25 cyst types). Empty cysts constituted 75-90% of cysts in the samples. Cyst assemblages were dominated by calcareous Peridiniales (30-70%) and Gonyaulacales (13-44%), represented mainly by Scrippsiella trochoidea and Lingulodinium polyedrum. In the first centimeter of sediment, cyst counts varied from 173 to 9, 933 cysts g(-1) wet weight, and increased in abundance in the inner area of the bay. Cysts of the toxic species Gymnodinium catenatum were also detected, and successful cyst germination of Alexandrium margalefii is described. Cyst abundance and distribution patterns suggest that the bay acts as a cyst trap, and that the cyst assemblages reflect the local community of meroplanktonic dinoflagellates.