engleski

Unusual zooplankton bloom in the open southern Adriatic Sea

The paper reports an unusual response of the microzooplankton community to oceanographic conditions observed during the winter of 2015 at the open South Adriatic. Record-breaking nauplii abundance of 13 734 ind. m-3 have been sampled for the open South Adriatic by 50 - μm net sampling. High densities were noted up to the 300 m depth for all copepods developmental stages The observed zooplankton maximum could have been ascribed to (i) warmer-than-usual surface and intermediate ocean temperatures, (ii) a high excess in precipitation preceding the samplings for a prolonged period, which freshened and widened surface layers and pushed saline Levantine Intermediate Water inflow below 400 m depth, and (iii) strong wind episodes that could transfer nutrients from coastal area to open ocean and induce limited vertical convention. The latter has been confirmed by observing neritic tintinnids species exclusively in the mesopelagic layer and autotrophic cells below the photic zone. Average seasonal maximum of zooplankton abundance is shifted from spring and early summer towards late winter months. Our results are documenting large and fast variations of production conditions, rarely found to occur in oligotrophic waters such as the South Adriatic Sea.

tintinnids ; nauplii ; copepods ; primary production ; Eastern Mediterranean

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