Structure and variability of a microbial community at a transect crossing a double gyre structure in the northeastern Adriatic Sea

Abstract

The effect of environmental conditions on bacterial community structures, production and enzymatic activities was studied in the northeastern Adriatic Sea in the late spring of 2009 in waters belonging to the cyclonic gyre (CG) and the anticyclonic gyre (AG), and in waters not affected by the presence of these 2 gyres. The AG and CG were formed in the same pool of warm, low-salinity, nutrient-rich waters characterized by increased autotrophic production and abundance. Differences in bacterial community structures and in intensities of cell-specific prokaryotic production and enzymatic activities indicated that CG and AG were isolated circulation cells in which water resided for different periods of time. Bulk prokaryotic production and enzymatic activities were significantly lower in the region outside the influence of the gyres. Bacterial communities of these waters, particularly in deeper layers, were likely introduced by highsalinity oligotrophic waters from the central Adriatic. © Inter-Research 2013, www.int-res.com.