Native fishes, exotic mammals, and the conservation of desert springs

Desert springs are fragile ecosystems that often harbor endemic species of fishes and other taxa. Historically, these springs experienced major disturbances from Pleistocene megafauna, aboriginal humans, and livestock. However, management practices to preserve and restore spring ecosystems and biota have led to the removal of livestock. We document changes in spring habitats and extinctions of fish populations due to management practices at two spring reserves: Ash Meadows in the southwestern United States and Dalhousie in central Australia. After springs were fenced and livestock removed, these ecosystems experienced increases in riparian vegetation, reduction of open-water habitat, and extinction of fish populations. Despite manual removal of vegetation to maintain open-water habitat, at least one pupfish population went extinct in Ash Meadows, and 18 populations, representing four of the five species native to desert springs in the Dalhousie reserve, also went extinct. To maintain the diversity of aquatic habitats and endemic biota, management of small desert springs must include substantial disturbance.