Global biodiversity is increasingly threatened by widespread anthropogenic impacts, which have accelerated since the First Industrial Revolution. Lowland rivers rank among the most affected ecosystems, having undergone centuries of hydromorphological modifications. The scarcity of historical data hampers precise assessments of biodiversity loss in these rivers since 1950, a critical threshold when anthropogenic pressures led to unprecedented ecological change. We compiled a comprehensive dataset of records of Ephemeroptera, Plecoptera and Trichoptera collected in time series from nine Czech lowland rivers over the past 140 years. Additionally, we integrated environmental data on water quality and hydroclimatic parameters spanning the last 60 years. Both alpha and gamma diversity declined steadily until the 1980s, followed by a partial recovery at the turn of the millennium due to water quality improvements. However, biodiversity recovery has remained limited in recent decades due to persistent pollution, climate change and potential depletion of the regional species pool. Assemblages are undergoing compositional changes driven by species turnover, rendering a return to their mid-20th-century baseline unlikely. Our results further highlight a dramatic loss of biodiversity already in the first half of the 20th century, which has not been offset by the partial recovery of rivers observed after 1990. Immediate actions are necessary to prevent further biodiversity decline and safeguard the ecosystem services of lowland rivers.
Bojková et al. (Fri,) studied this question.