Impacts of extreme events on southeastern Australian freshwater crayfish

Extreme events like wildfire, flooding and drought, and activities related to managing these events (fire dam, bridge and road construction and water regulation) potentially impact freshwater crayfish populations, although limited information exists. Our study analysed abundance data for four freshwater crayfish species across an 11-year period, including pre- and post-wildfire and post-flooding data, and described the impacts of human actions on their populations in the Grampians National Park in Victoria, Australia. Wildfire and flooding were generally associated with reduced crayfish abundances for Euastacus bispinosus, Cherax destructor, Geocharax falcata and Gramastacus insolitus, but in some habitats, C. destructor, G. falcata and G. insolitus did not decline. A general trend of decreasing abundances for all species was evident over the study period, likely due to the landscape-scale impacts of wildfire, flooding and the shrinking of available habitat during drought. Southeastern Australia is a crayfish biodiversity hot-spot and increased frequencies of wildfire, flooding and drought are forecast for this region as climate change progresses, threatening crayfish populations. Therefore, it is important that disaster recovery management seeks to minimise additional damage to crayfish habitat availability and connectivity.