Eutrophication of the Mastník bay of the Slapy Reservoir, Czechia
This article investigates the changes in water quality in the Mastník bay, a part of the Slapy Reservoir located at the Vltava River, during the 2015–2019 period. Due to the occurrence of drought conditions smaller streams in rural areas of Czechia have suffered from a low water quality, especially in the summer. For these reasons, the Mastník stream contributes to the abnormal eutrophication of the Mastník bay. Since the exchange of water between the bay and the rest of the Slapy reservoir has been limited, a large increase in the phytoplankton biomass has been observed in the Mastník bay. Consequently, the concentrations of chlorophyll in the Mastník
bay increased over the last 15 years, with the chlorophyll-α concentration exceeding 500 μg I−1 during the summer months in several cases. Based on the concentrations of total nitrogen, total phosphorus, chlorophyll and water transparency measured by this study, the Mastník bay is evaluated as being hypertrophic. In contrast, no significant effect of the Mastník bay on the concentrations of the monitored parameters has been demonstrated in the remaining parts of the Slapy Reservoir.