Distribution of dinoflagellate cysts in recent sediments from Izmir Bay (Aegean Sea, Eastern Mediterranean)

To determine the species composition, abundance and horizontal distribution of dinoflagellate cysts in recent marine sediments, samples were collected at 13 stations in Izmir Bay, Aegean Sea. At least thirty-six dinoflagellate cyst types were identified, with the assemblages mainly dominated by Lingulodinium machaerophorum, Polykrikos kofoidii, Operculodinium centrocarpum, Gymnodinium cf. nolleri and Quinquecuspis concreta. Total cyst concentrations ranged from 41 to 3292 cystsg− 1 dry weight sediment. The majority of the cysts occurred in the inner and middle parts of the bay, where higher cyst concentrations were observed. According to the One Way Anova test, the difference between stations was significant statistically (p < 0.05). Two of the dinoflagellate cyst species have not been recorded previously as cysts or motile stages in Aegean marine waters; Gymnodinium cf. nolleri and Oblea acanthocysta. Alexandrium minutum and Alexandrium affine type cyst were observed at almost all stations although the cyst type of the Alexandrium catenella/tamarense complex was only found in the outer bay. These findings indicate potential seedbeds for initiation of future blooms and outbreaks of potentially toxic species in Izmir Bay.

Research Highlights
► L. machaerophorum and P. kofoidii that indicate eutrophication in the Izmir Bay.
► G. cf. nolleri and O. acanthocysta were new records to Aegean coastal water.
► Potentially toxic cyst types of A. minutum and O. centrocarpum indicate seedbeds.