LAUSR

Functional traits can be used to identify various ecosystem processes that are influenced by natural and anthropogenic factors. We tested the hypothesis that the species composition and functional feeding traits of zooplankton are influenced by environmental gradients, such as depth, trophic status, and ion content. This hypothesis was tested in three lignite strip mine lakes in Central Poland. Two shallow, polymictic lakes were reclaimed (1994 and 2008), and the third deep, stratified lake has been reclaimed during the flooding process, since 2011. Samples were collected monthly in 2016 and 2017. The functional responses of zooplankton communities to environmental variables were tested through redundancy analyses. Both eutrophy and oligotrophy contributed to the taxonomic heterogeneity and functional homogeneity of zooplankton. In eutrophic condition small microphagous rotifers and small-sized crustaceans dominated, while oligotrophy and high ion concentrations favored dominance of large microphagous and stationary/suspended feeders. In turn, the depth gradient of a newly emerging, stratified lake resulted in taxonomic and functional heterogeneity of zooplankton. Our results complement existing knowledge about zooplankton in post-industrial areas, and also provide new information on the mechanisms of formation and functioning of mine pit lake ecosystems.