Distribution and activity of prokaryotic microorganisms in the central and southern Adriatic Sea

Šantić, Danijela (2010) Distribution and activity of prokaryotic microorganisms in the central and southern Adriatic Sea . Doctoral thesis, Faculty of Science > Department of Geology.

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Abstract

This work analyzes spatial-temporal distribution of the abundance of heterotrophic bacteria, cyanobacteria genus Synechococcus and Prochloroccus as well as heterotrophic nanoflagellates as the main predators of prokaryotic microorganisms. There is also presented the share of HNA and LNA bacteria in the total population of heterotrophic bacteria and estimated bacterial activity based on bacterial production. On the basis of data on the abundance and production of heterotrophic bacteria, the sea of the researched area is characterized as oligotrohic. The exceptions were the areas that are under direct influence of the Krka, Jadro and Neretva Rivers. The analysis of the share of HNA and LNA bacterial groups in the community of heterotrophic bacteria showed the prevailing of HNA bacteria at the stations of a higher trophic level, while LNA bacteria dominated at the open- sea stations of Jabuka Pit and the Šibenik area. Studying the activity of bacteria in relation to the presence of HNA and LNA bacteria, the highest share of HNA bacteria was found in the areas of highest bacterial activity (Šibenik area, Kaštela Bay). Within other coastal areas, from Zadar to Dubrovnik, and at the open sea during the highest values of bacterial production in the community of heterotrophic prokaryotes the most dominating was LNA bacteria, indicating the activity of both groups of bacteria in the study area, particularly the activity of LNA bacteria in the oligotrophic area. The presence of cyanobacterial genera Synechococcus and Prochlorococcus was found at all researched stations, with slightly marked differences between the coastal and open-sea stations. In the total biomass of the researched prokaryotic community the heterotrophic prokaryotes dominated in the entire researched area, except in the Dubrovnik area where the predominant genus was Synechococcus, and at the open sea of the Šibenik local waters, where the biomass share of heterotrophic and autotrophic prokaryotes was equable. The strong dependence of heterotrophic bacteria, especially HNA group of bacteria, on the organic substance of phytoplankton origin in the coastal area during the warmer period, indicates the importance of "bottom up" control, while that dependence on the open sea suggests a possible competition relationship between bacteria and cyanobacteria for nutrients. Control of bacteria by predation was the strongest in the Šibenik area that is of the highest trophic level, and where it was determined that the HNA bacteria were important prey for HNF, while at open sea sites LNA bacteria and Synechococcus were more important prey for HNA.

Item Type: Thesis (Doctoral thesis)
Keywords: Adriatic Sea, heterotrophic bacteria, HNA bacteria, LNA bacteria, bacterial production, heterotrophic nanofagellates, Synechococcus, Prochlorococcus
Supervisor: Krstulović, Nada
Date: 2010
Number of Pages: 165
Subjects: NATURAL SCIENCES > Geology
NATURAL SCIENCES > Interdisciplinary Natural Sciences > Marine Science
Divisions: Faculty of Science > Department of Geology
Depositing User: Sonja Borak
Date Deposited: 29 Jan 2014 11:42
Last Modified: 29 Jan 2014 11:42
URI: http://digre.pmf.unizg.hr/id/eprint/283

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