Assessing the vulnerability of freshwater crayfish to climate change

Climate change is a major threat to the persistence of biodiversity. Global assessments highlight the most climate vulnerable species and geographic regions based on species traits and measures of exposure to climate change. Yet the majority of climate change vulnerability assessments have focused on terrestrial and marine vertebrates and largely ignored the less well-known freshwater species and invertebrates. We present the first global analysis of 574 species of freshwater crayfish (Families: Astacidae, Parastacidae and Cambaridae) using IUCN's trait-based vulnerability assessment protocol. Location: Global. Methods: We collected species-specific information on sensitivity (eight traits), adaptive capacity (four traits) and exposure (five traits) to climate change and combined those dimensions to assess overall species vulnerability. Results: Our results predicted that 87% of freshwater crayfish species are highly sensitive to climate change (primarily due to habitat specialization), 35% have low adaptive capacity and 57% are highly exposed (based on an ensemble mean of four general circulation models for a moderate Intergovernmental Panel on Climate Change (IPCC) scenario, RCP6.0). Combining sensitivity, low adaptive capacity and exposure, we assessed 87 species (15%) as vulnerable to climate change. These species are distributed globally with high concentrations in the south-eastern USA (36 species), south-eastern Australia (21 species) and Mexico (10 species), reflecting global patterns of crayfish species richness. Of the 91 species listed as threatened by climate change in the IUCN Red List, we predicted 18 species to be climate change vulnerable. Main conclusions: We identified hotspots of species vulnerable to climate change that require further conservation attention. The IUCN trait-based protocol can help identify data gaps and key traits that should be investigated further and thus can help overcome knowledge shortfalls on the effects of climate change. Our study provides key insights for the application of climate change vulnerability assessment to data-poor invertebrates, which remain underrepresented in global conservation priorities.