CALCAREOUS NANNOPLANKTON FLUCTUATION, PROXY FOR HOLOCENE ENVIRONMENTAL CHANGES IN THE BLACK SEA.

The calcareous nannoplankton represents a group of major components of the oceanic phytoplankton, situated at the base of the trophic chain. The evolution pattern of these organisms is relevant in the past geological record and nowadays, for several research fields, such as: marine biology, marine geology, biogeochemistry, micropaleontology, biostratigraphy as well as paleogeographic and paleoclimatic reconstructions, including the paleoenvironmental ones. Taking into account that the calcareous nannoplankton species (namely calcareous nannofossils for the extinct taxa) already occur at the end of the Triassic, based on the fluctuation pattern in abundance and diversity, past climate and environmental changes may be revealed for approximately the last 205 million years. As the Black Sea basin experienced significant sea-level fluctuations and paleoenvironmental changes during its geological record, and especially within the Pleistocene-Holocene interval, the calcareous nannoplankton is employed for deciphering the aforementioned changes. Several investigations, including those presented herein, took place in the Black Sea based on this group of organisms both in the deeper parts of the basin and in the shallow ones (i.e., the continental shelf), revealing significant fluctuations of the extinct and extant assemblages. [ABSTRACT FROM AUTHOR]