Picoplankton and temperature dynamic in the Mar Piccolo of Taranto (Northern Ionian Sea).

Picoplankton is composed of both < 2 micron pico-sized heterotrophic bacteria and autotrophic pigmented organisms, all involved in the functioning of the microbial loop. The microbial loop represents a sensitive descriptor of changes in environmental conditions, and microbial assemblages (e.g. heterotrophic and autotrophic picoplankton) due to their very high turnover rates are assumed to respond rapidly to any environmental change. On account of these features, microbial assemblages have been recently proposed as tools for monitoring the functioning of aquatic ecosystems. In this framework in the present study we determined autotrophic and heterotrophic picoplankton densities, for two years, in the Mar Piccolo of Taranto and their relationships with the temperature. Results evidenced that picoplankton abundances were comparable to those of other polluted coastal environment subjected to antrophogenic inputs. A significant relationship was found between temperature and both autotrophic (r = 0.72, p < 0.05) and heterotrophic (r = 0.84, p<0.05) picoplankton.