Morphological Plasticity of Dominant Species in Response to Nutrients Dynamics in Bidighinzu Reservoir of Sardinia, Italy

The aim of this study was to describe the effect of environmental factors on the variation in population structure of phytoplankton in a hypertrophic reservoir and to analyse the size variability of dominant species, and finally to try to find a linkage between environmental factors and phytoplankton size structure. Species composition and dynamics of phytoplankton were typical of highly trophic conditions and were frequently characterized by the dominance of cyanobacteria, Microcystis, Anabaena, Aphanizomenon. Some environmental parameters play an important role in determining the phytoplankton community succession and their size structure, favouring or limiting the growth of the different groups of the phytoplankton. The results indicate that overall nutrient concentrations in Bidighinzu Lake were not limiting the phytoplankton growth in general. on the contrary, concentrations of nutrient were always above the required levels for phytoplankton growth. The results Show that phytoplankton community succession and their seasonal variability of size structure (consequently cell surface area, cell volume and surface area to volume ratio) were mostly influenced by the temperature and nutrients. However, these affecting factors (especially nutrients) on seasonal variability of size structure of common species in Lake Bidighinzu showed difference among the species.