The impact of climate-related extremely low river levels on zooplankton in two oxbow lakes of a temperate river (the lower Vistula, Poland)

Oxbow lakes are important elements of river valleys. Regardless of whether they are natural or artificial (e.g., oxbow lakes of the lower Vistula), they play a key role in water retention and biodiversity maintenance. To function properly, they need to be regularly flooded by rivers. Unfortunately, due to accelerated climate change, water levels in rivers and oxbow lakes have dropped dramatically. Climate change is responsible for temperature rise (which increases evaporation) and decreased precipitation. The aim of study was to evaluate the impact of climate change on the environmental conditions and zooplankton population in two different oxbow lakes. Decreased water levels lead to higher water fertility and dominance of eurytopic organisms, mainly rotifers in the zooplankton. Rotifer species thrive because they are able to adapt to a wide range of environmental conditions. In addition, low water levels affect biodiversity in oxbow lakes and threaten the proper functioning of these water bodies.