A simple modelling approach to simulate the effect of different climate scenarios on toxic cyanobacterial bloom in a eutrophic reservoir

Toxic cyanobacterial blooms are of major concern in eutrophic inland waters due to their water quality deterioration capabilities. Understanding their dynamics and driving factors is of great importance to manage bloom events and their consequences. Ecosystem models enable us to simulate, analyze and understand ecological processes in complex aquatic ecosystems. In this work, we examined the ability of the General Lake Model-Aquatic EcoDynamics (GLM-AED), an open-access one dimensional hydrodynamic-ecological model to simulate physical variables and the dynamics of two cyanobacterial species in 2016. The effect of possible hydrological and climatic scenarios on cyanobacterial blooms occurrence was also investigated. Results indicate that the model was able to accurately reproduce changes in water level (MAPE of 0.4%), water temperature profiles (MAPE of 5 to 7%) and the biomass of Microcystis aeruginosa and Chrysosporum (Aphanizomenon) ovalisporum at the study area. Dramatic changes were observed under warming trends including increase in both the length of the stratification period and in cyanobacteria bloom dynamics. Data analysis revealed that while water temperature was the primary factor determining cyanobacterial succession and occurrence, other factors such as water level fluctuations and irradiance are also important. Our findings suggest that any further increase in temperature would promote the development of potentially toxic cyanobacterial blooms at Karaoun Reservoir. The good performance of the model will provide essential insights required for deeper ecological understanding and water quality management. (C) 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.