Unexpected benefits of the July 2010 Warm Springs wildfire for recovery actions for the endangered Moapa dace, Moapa coriacea.

Authors: David J. Syzdek, Brian M. Hobbs

Year: 2010 (xlii)

Abstract

The Moapa Warm Springs in southern Nevada is a regional spring complex that is the headwaters of the Muddy River. These naturally-thermal springs and associated streams are habitat for an endemic suite of thermophilic aquatic species that includes the federally endangered Moapa dace (Moapa coriacea). Currently, the Southern Nevada Water Authority (SNWA) and stakeholders are undertaking recovery actions for the Moapa dace and its habitat. These include construction of fish barriers, reduction in or removal of non-native and invasive species, riparian and aquatic habitat restoration, and development of an ecological model for the Moapa dace. To facilitate recovery of the dace and other native species, SNWA purchased the 1,218-acre Warm Springs Ranch in September 2007 and designated it the Warm Springs Natural Area for conservation and environmental stewardship purposes. However, soon after the property’s acquisition by SNWA, Moapa dace numbers declined to their lowest levels ever recorded. Working with the US Fish and Wildlife Service (USFWS), Nevada Department of Wildlife (NDOW), and the US Geological Survey, SNWA is conducting stream restoration work and intensive habitat improvements to reverse the population’s decline. Following their nadir in February 2008, dace numbers began to increase, but a human-caused wildfire on 1 July 2010 burned over 600 acres of woodland near many of the streams that contain dace. Despite initial fears that Moapa dace would suffer catastrophic declines from the fire, post-fire fish surveys indicate a continued upward trend in dace numbers. In fact, the fire cleared enough non-native riparian vegetation to allow NDOW to treat a section of the Muddy River with rotenone to control the invasive and predatory blue tilapia (Oreochromis aureus) one year ahead of schedule. Furthermore, post-fire clearing of dense stands invasive tamarisk (Tamarix spp.) and fan palms (Washingtonia spp.) will facilitate the control of these non-native species and will aid in the re-establishment of native riparian vegetation.