Long-term abiotic changes in two technogenic lakes in the Wadi El-Rayan depression (Egypt)

Context The 38-year long-term changes of six abiotic characteristics in two artificial desert lakes. Aims To investigate the long-term dynamics of salinity, water temperature, transparency, oxygen content, total phosphorus and nitrogen. Methods From 1984 to 2022, seasonal data were collected on 10 sites in two connected lakes, and statistical analysis was applied to them. Key results All studied parameters changed in both lakes. Salinity changed differently in lakes, as well as some other characteristics. This was due to the individual peculiarities of lakes, namely one being flowing, and another being terminal. In both lakes, the water temperature increased, which was more pronounced in the terminal lake. Some quasiperiodic changes were also noted. Conclusions This study presents the largely neglected effect of interactions between regional climatic changes and individual lake peculiarities, as well as between directed trends and natural cycles. Implications This information is valuable for the management of waterbodies, resource use and the development of sustainable polyaquaculture in them.