Direct and indirect impacts of wildfire on faunal communities of Mediterranean temporary ponds

Abstract

Abstract The Mediterranean region has historically been affected by wildfires. However, studies addressing wildfire impacts have traditionally focused first on terrestrial systems and second on lotic systems. This bias has left a gap in knowledge related to wildfire effects on some of the emblematic habitats of the Mediterranean region such as temporary ponds. We hypothesise that temporary ponds will experience indirect consequences of wildfires like those of other aquatic systems (e.g. nutrient increases or trophic alterations). However, the fact that temporary ponds are dry during the summer, when most wildfires occur, could add a new path of disturbance such as an impact on organisms aestivating in the pond sediment due to their direct burning. Based on these hypotheses, the present study analyses wildfire impacts on faunal communities adapted to temporality, focusing on species traits related to expected indirect and direct impacts (i.e. dispersal ability, life history or feeding habits). We took advantage of a wildfire (summer 2012) that partially affected a Mediterranean temporary pond network, comparing the environmental and the faunal community responses from before and after the wildfire, and between the burned and unburned ponds during the subsequent hydroperiod. As hypothesised, our results indicated different wildfire effects. First, changes in abundances of some trophic groups from before and after the wildfire but also strong fluctuations at the beginning of the hydroperiod between burned and unburned ponds. Second, a decrease in abundance of organisms that remain in the pond sediment during drought in burned ponds, being probably affected directly by the wildfire. Only one hydroperiod appears to be sufficient for burned ponds to recover their similarity to unburned ponds, which highlights the high resilience of these communities. Despite their resilience, these communities could become compromised in the future since global change scenarios predict increase wildfire frequency and intensity in the Mediterranean region.