Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic

Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, understanding primary drivers diversity. We examined benthic macroinvertebrate diversity using a dataset >1,500 lake river sites. Rarefied ? within catchments was assessed along temperature gradients. Community composition region-scale analysis ? its components (nestedness turnover), biotic–abiotic relationships. lakes rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity related air temperature, lowest coldest catchments. Regional dissimilarity highest when were compared islands, suggesting that connectivity limitations led strongest dissimilarity. High contributions nestedness indicated island contained subset found regions. predominately occupied by Chironomidae Oligochaeta, whereas Ephemeroptera, Plecoptera, Trichoptera abundant at latitudes. associated geology precipitation also important correlates. The strong association supports prediction warming will increase low on islands suggests this be limited biogeographical constraints. Long-term harmonised monitoring region necessary detect inform science-based management.