Habitat restoration and long-term conservation of Ash Meadows naucorids

Authors: Michael S. Parker, Darrick S. Weissenfluh, Shawn C. Goodchild, Cristi R. Baldino, Lee H. Simons, Carl Lundblad, Phillip Cunningham

Year: 2009 (xli)

Abstract

Conservation of thermal endemic invertebrates within spring systems of the Ash Meadows National Wildlife Refuge will require active management to insure the long-term persistence of suitable habitat conditions. We have monitored population responses of two endemic creeping water bugs, the Ash Meadows and relict naucorids (Ambrysus amargosus and A. relictus), to changes in habitat conditions brought about by active management and long-term succession within restored and unmanipulated channels. Within the Point-of-Rocks system, A. amargosus populations increase in response to habitat manipulations that provide more diverse substrate particle size distributions and reduce negative impacts of encroaching terrestrial vegetation. In February 2009, water diverted to the Devils Hole pupfish refuge was returned to the main spring channel at Point-of-Rocks, nearly doubling the discharge and extending suitable habitat for thermal endemic invertebrates within the natural channel. Naucorids recovered from the refuge outflow were introduced into a restored spring channel in which Naucorids had been extirpated. Additional reintroductions from robust populations in restored channels are proposed to reestablish naucorids throughout more of their historic range. Reintroduction of A. amargosus into the restored Kings Pool outflow in 1998 resulted in a rapid population increase followed by a gradual decline and ultimate loss of the species from the system in 2002. Large shifts in community structure, including invasion of the restored system by cattails and exotic crayfish, reduction of primary production due to channel shading by natural succession of terrestrial vegetation, and increase in diversity and abundance of predatory invertebrates and fish are likely contributed to the loss of this reintroduced population. Lessons learned from past these past manipulations are informing future restoration, reintroductions, and long-term management of these dynamic spring systems.