Climate effects PERSiST

Modelling streamflow impacts on aquatic ecology

Future patterns of streamflow are likely to be a primary driver of aquatic ecology. Using rainflow runoff models such as PERSiST may be one way to evaluate the possible impacts of climate change and land management on the ecology of vulnerable aquatic species. José Ledesma and colleagues published such a study to evaluate future habitat availability the the Montseny brook newt (Calotriton arnoldi). They concluded that future low streamflow conditions will likely pose a severe threat for the survival of the Montseny brook newt but appropriate local management actions including limiting the expansion of holm oak forest may increase the chances for species survival.

The Montseny brook newt is a critically endangered amphibian species which inhabits a small 20 km2 holm oak and beech forest area in northeast Spain. The species can only live in running waters and might be highly vulnerable to hydrological perturbations such as increased drought frequency that could occur under climate and vegetation cover changes. Scenarios describing potential changes in species habitat due to global and local environmental changes can help identify and prioritize the actions needed for its conservation. Based on knowledge of the species and supported by observations, José Ledesma and colleagues proposed daily low and high streamflow event thresholds for the viability of the species. They used PERSiST to simulate changes in the frequency and duration of streamflow events under two climate and four vegetation cover scenarios for near-future (2031–2050) and far-future (2081–2100) periods in a reference catchment. All future scenarios projected a significant decrease in annual streamflow (between 21% and 67%) with respect to the reference period. The frequency and length of low streamflow events was also projected to dramatically increase. In contrast, the risk of catastrophic drift linked to flash floods was projected to decrease. Local hydrologcial effects associated with a potential change in vegetation toward an expansion of holm oak forests will likely be more important than climate changes in determining threshold low flow conditions. This indicates that consideration of both local (potential changes in vegetation) and global (temperature and precipitation) is essential in simulating future aquatic habitats.