Summer Coccolithophore Community in the Western Black Sea: Comparison with North Aegean Records

Postgraduate Thesis uoadl:2876904 36 Read counter

Κατεύθυνση Περιβάλλοντα Ιζηματογένεσης, Οικοσυστήματα και Γεωβιοπόροι
Library of the School of Science
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Ravani Alexandra
Supervisors info:
Δήμιζα Μαργαρίτα, Επίκουρη καθηγήτρια, τμήμα Ιστορικής Γεωλογίας και Παλαιοντολογίας,τμήμα Γεωλογίας και Γεωπεριβάλλοντος, ΕΚΠΑ
Original Title:
Summer Coccolithophore Community in the Western Black Sea: Comparison with North Aegean Records
Translated title:
Summer Coccolithophore Community in the Western Black Sea: Comparison with North Aegean Records
The Black Sea is the largest semi-enclosed marginal sea and receives drainage from almost one-third of continental Europe. Intensive coccolithophore blooms (Emiliania huxleyi, primarily) are typical events for the Black Sea. The main aim of this study is to determine the spatial and vertical distribution patterns of living coccolithophores from the oxic surface zone in the western part of the Black Sea in June 2016. A total of 95 plankton samples from 33 stations were taken from discrete water samples (1 to 50 m depths) that were collected from inner, outer shelf and open sea zones. Living coccolithophores showed excessively high densities, ranging from 2.44x104 to 7.63x106 coccospheres l–1. Emiliania huxleyi dominated in the surface assemblage and constitutes the 98% of the coccolithophore community. Differences in spatial distribution between inner shelf and open-sea environments were observed that are primarily associated with freshwater inputs and associated nutrients from the Danube river. In general, this species was usually higher in the surface layer (up to around 35 m), and tended to decrease in density below ~35 m water depth, while Algirosphaera robusta occurred in high densities (up to 7.94x106 coccospheres l–1), indicating low light availability below the thermocline (Kleijne, 1993; Young, 1994). A strong positive correlation between E. huxleyi density and CTD-fluorescence data but also Chl a concentrations indicate a direct relationship between coccolithophores and chlorophyll a. The significantly low coccolithophore and E. huxleyi concentrations of Northeastern Aegean assemblage in the summer period (Karatsolis et al., 2017), when BSW presented maximum inflow, are probably connected with the strong stratification of the Aegean Sea and the fact that the water that inflows to the surface of the Northeastern Aegean Sea from the Black Sea through the Dardanelles Strait is low in nutrients (Lagaria et al., 2017).
Main subject category:
coccolithophores, phytoplankton, Black Sea, North Aegean, Emiliania huxleyi, Algirosphaera robusta
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