Hydrological Instability of Ponds Reduces Functional Diversity of Freshwater Molluscs in Protected Wetlands

Different facets of biodiversity of freshwater molluscs were compared in 21 small ponds located in the wetland area around Lake Luknajno (Nature Reserve protected by Ramsar Convention, UNESCO Biosphere Reserve). The ponds examined between 2010 and 2019 differed in their susceptibility to periodical drying out. In addition, the hydrological stability of many of them was significantly reduced in 2015-19 as a result of climatic changes (decrease in precipitation, shortening of the snow cover period, increase in the average temperature during the growing season, increase in the frequency of heat waves). The functional diversity of molluscs decreased linearly and monotonically with the increase in the frequency and intensity of drying up of ponds, so it can be treated as a good indicator of their hydrological instability. Other facets of biological diversity - taxonomic and phylogenetic - were unimodally related to differences in stability. Along time, species resistant to desiccation being specialized inhabitants of temporary water bodies clearly increase their percentage, and the share of species less resistant decreases.

Automated summary

This study compared different facets of biodiversity of freshwater molluscs in small ponds around Lake Luknajno wetland area. The results showed that the frequency and intensity of pond drying up had a negative impact on the functional diversity, taxonomic diversity, and phylogenetic diversity of molluscs.