Investigation of modern dinoflagellate cysts distribution in Izmir bay

Dinoflagellates, together with diatoms, represent one of the most important groups in the marine phytoplankton. Some dinoflagellates produce a resting cyst which can survive harsh environmental conditions in their life cycle. Dinoflagellate cysts are used as indicators of sea surface parameters (temperature, salinity, nutrient and primer production) and modern dinoflagellate cysts can be a database to reconstruct the evolution of sea surface conditions in decadal and millennial time scales. Studies of cyst distribution and abundance is important to evaluate harmful algal blooms which harmful and resting cyst producer species cause.Izmir Bay is one of the greatest natural bays of Aegean Sea. In this study, 16 surface sediment samples have been collected in Izmir Bay between 2008-2009 to determine horizontal distribution and abundance of the cysts. A total of 31 dinoflagellate cyst type (two cysts were unidentified in literature before) have been identified and recorded concentrations between 80-31532 cyst/g dry weight sediments. Lingulodinium machaerophorum, Polykrikos kofoidii, Quinquecuspis concreta, Duridinium caperatum and Spiniferites bulloideus species are dominated over other species to cyst concentration. Alexandrium minutum A. catanella/tamarense complex, A. affine type, Lingulodinium machaerophorum, Operculodinium centrocarpum and Operculodinium israelianum, Spiniferites hypercanthus and Spiniferites mirabilis potentially toxic cyst species were observed in the sediments of Izmir Bay. The presence of these cysts, in particular where higher abundances were found, indicates potential seedbeds for initiation of future blooms and subsequent outbreaks of toxic or other harmful events.The Izmir Bay is especially susceptible to the formation of HABs attributed to high biomass dinoflagellate blooms. Owing to these blooms and the relative characteristic features of this area, cyst formation and concentration is high in numbers.