Naslov
Seasonal and vertical distribution of planktonic bacteria and heterotrophic nanoflagellates in the middle Adriatic Sea

Autori
Šestanović, Stefanija ; Šolić, Mladen ; Krstulović, Nada ; Ninčević, Živana

Izvornik
Helgoland marine research (1438-387X) 58 (2004); 83-92

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Bacteria; Heterotrophic nanoflagellates; Seasonal distribution; Temperature; Adriatic Sea

Sažetak
Temporal and spatial patterns of bacteria and heterotrophic nanoflagellates (HNF) were studied monthly from January 1997 to December 1998 in the middle Adriatic Sea. Bacterial and HNF relationships with phytoplankton biomass and temperature were analyzed to examine how the relative importance of bottom up and top down factors may shift over seasons and locations. For the coastal area, an inconsistent relationship between bacterial abundance and chlorophyll a and a stronger relationship between bacterial abundance and bacterial production, suggest that other substrates than those of phytoplankton origin are important for bacteria. The analysis of simultaneous effect of temperature and bacterial production on bacterial abundance showed that the effect of temperature obscured the effects of bacterial production, suggesting that bacterial growth itself is highly temperature- dependent. The relationship between HNF abundance and bacterial abundance was slightly improved by inclusion of in situ temperature, bacterial production or both parameters, as additional independent variables. About 60% of the variability in HNF abundance can be explained by bacterial abundance, bacterial production and temperature. In the open sea, tight coupling of bacteria abundance with chlorophyll a concentrations implied a dominant role of substrates derived from phytoplankton in controlling bacterial abundance. During the colder months bacterial abundance was high enough to support higher HNF abundance than observed, suggesting that predation exerted a minor depressing influence on bacterial abundance during that period. During the spring-summer period, HNF controlled bacterial standing stocks by direct cropping of bacterial production.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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