Environmental factors influencing the abundance and spatial distribution of modern dinoflagellate cysts in Izmir Bay (Eastern Mediterranean).

We analyzed surface sediments from 12 stations located in Izmir Bay to determine the impact of anthropogenic pollution on dinoflagellate cysts. Forty-three dinoflagellate cyst taxa and two cyst assemblage zones were identified. Zone 1 is characterized by the dominance of cysts of Gymnodinium nolleri , Selenopemphix nephroides, and Operculodinium centrocarpum from the oligotrophic part of Izmir Bay. Zone 2 is in the highly productive inner part of the bay and is characterized by the high abundances of Lingulodinium machaerophorum , Spiniferites ramosus , cysts of Scrippsiella spp., cysts of Polykrikos spp. and Quinquecuspis concreta. We used multivariate statistical analysis (DCA and CCA) on dinoflagellate cysts and environmental variables to support the identification of Zones 1 and 2. Our analyses also revealed that summer and winter chlorophyll- a as well as elevated nitrate and nitrite concentrations are significant parameters in controlling dinoflagellate cyst distribution in Izmir Bay. • The importance of L. machaerophorum as an indicator of eutrophic conditions in Izmir Bay. • Autotrophic dinoflagellate cysts were more abundant than heterotrophic. • Cyst assemblages reflect the eutrophic (inner) and the oligotrophic (outer) parts of Izmir Bay. • Inner Izmir Bay is N-limited and outer Izmir Bay is P-limited. [ABSTRACT FROM AUTHOR]