Do mucilage events influence pico- and nanoplankton size and structure in the Adriatic sea? |
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Authors: | Silvana Vanucci |
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Institution: |
a Department of Animal Biology and Marine Ecology, University of Messina, S. Agata, Messina, Italy |
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Abstract: | Temporal changes in abundance and biomass of picophytoplankton, heterotrophic pico-eukaryotes, and nanoplankton assemblages were investigated along a transect crossing the Adriatic Sea, from the Italian to the Croatian coast. This 15-months (June 1999-August 2000) investigation allowed comparing microbial parameters during summer 1999 (year without mucilage) and summer 2000 when a major mucilage event occurred. Pico- and nanoplankton assemblages displayed significant differences between the 2 summer periods. The main differences can be summarized as: (i) presence of cyanobacterial blooms (up to 108?cells?l-1) in summer 2000, absent in summer 1999; (ii) an increasing fraction of heterotrophic pico-eukaryotes (up to 5.0?×?106?cells?l-1) and heterotrophic nanoplankton (size 2-5?µm) during mucilage event; (iii) a reduced abundance of small-sized (2-3?µm) phototrophic nanoplankton in summer 2000. Changes in community structure were signals of changes in trophic condition of the system, which resulted in a competitive advantage for small sized pico- and nanoheterotrophs. Data presented here indicated that mucilage events are associated with changes in microbial community structure and functioning in ambient water and induced the amplification of 3-step microbial food chain. The potential use of the heterotrophic pico-eukaryotes for describing alterations of the trophic pathways during mucilage events is discussed. |
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Keywords: | Mucilage Nanoplankton Microbial food web Heterotrophic pico-eukaryotes |
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