Speranza Claudia Panico*, Alessandro Pedretti, Damiano Virgilio and Guido Incerti
Context: Phytoplankton is a crucial component of limnic ecosystems as being the foremost representative of primary producers, then sustaining the whole trophic network. The aim of this study is to evaluate the effects of changing environmental conditions, in the period 2011-2023, on phytoplankton community’s structure and successional dynamics in a temperate-meso/eutrophic-lake in NE Italy.
Methods: Single taxa and diversity metrics based on biovolume data were related to physicochemical variables (temperature, pH, electrical conductivity and dissolved oxygen) along the water column, and concentrations of macronutrients (nitrite, nitrites and phosphorus) and herbicides (2-hydroxyatrazine, 2-hydroxy-terbuthylazine, desethylterbuthylazine, terbuthylazine, metolachlor and metolachlor ESA) collected on a monthly base for the 12-years period.
Results: The results showed that seasonal physicochemical dynamics and nutrients loading were the principal variables affecting the annual cycling of phytoplankton community composition. Different responses to herbicides loads were found for different functional guilds. Interpretation: The expected succession, characterized by diatoms dominance in the cold season, did not match completely the pattern found at the study site. Rather, a local dominance of Cryptophyceae in winter was related to a high competitivity and tolerance to eutrophication. Considering impacts by herbicides, sensitive groups such as Cryptophyceae and Euglenophyceae dominate the phytoplankton community at low herbicides loads. When loadings increase, following resuspension from sedimental deposits after anoxic conditions enhanced by increasing temperature, more tolerant and competitive groups emerge such as Cyanophyceae and Dinophyceae.
Conclusion: Given the importance of phytoplankton’s community for the ecological assessment of water quality evaluation in lakes and water reservoirs, our study provides a relevant contribution towards the full understanding of the interplay between climate warming and anthropogenic impacts along the phytoplankton ecological succession.
Published Date: 2025-03-28; Received Date: 2024-11-11
