Land Use Influences on Freshwater Biodiversity

ABSTRACT Aim Land‐use change is a major driver of biodiversity loss, but most generalisations about its effects come from terrestrial ecosystems. Given the fundamental differences in spatial structure and community assembly processes between terrestrial and freshwater ecosystems, biodiversity responses to land‐use change may diverge. Here, we aim to advance understanding of the generality of land‐use impacts on freshwater ecosystems across spatial scales. Location Freshwater ecosystems across 33 countries. Time Period 1984–2017. Major Taxa Studied This study covers 6 major freshwater biological groups including algae, macrophytes, zooplankton, macroinvertebrates, fish and amphibians. Methods We analysed species‐level abundance data from 163 studies across 33 countries that compared assemblages in natural areas with those in landscapes dominated by urban, agricultural, or forestry. We quantified land‐use effects on species richness and relative abundance at both local (α) and regional (γ) scales, and assessed spatial turnover (β‐diversity) within each land‐use type. We further examined whether these responses varied geographically and across biological groups. Results All three land‐use types reduced species richness and altered relative abundance structure compared to natural vegetation, with urban systems showing the strongest and most consistent declines. Only urbanisation was associated with biotic homogenisation, particularly among species that were abundant. Biodiversity responses to land‐use change also varied with latitude and taxonomic group: tropical assemblages tended to differentiate across sites, whereas homogenisation was more common at higher latitudes. Macroinvertebrates and fish showed the strongest overall declines in the face of land use. Main Conclusions Freshwater biodiversity responds to land‐use change through distinct, scale‐dependent pathways that are not generalizable from previous work in terrestrial ecosystems, likely reflecting the physical structure and ecological dynamics of freshwater ecosystems.