Interactive advantage of Ash Meadows pupfish over sailfin molly and implications for Ash Meadows Spring system rehabilitation

Authors: Gayton G. Scoppettone, Peter H. Rissler

Year: 2009 (xli)

Abstract

Habitat use and interactions of Ash Meadows pupfish (Cyprinodon nevadensis minonectes) and sailfin molly (Poecilia latipinna) were studied to generate information useful for reducing non-native sailfin molly in spring-pool habitat in the Mojave Desert’s largest oasis, Ash Meadows, Nevada. In situ studies indicated that pupfish reduced sailfin molly reproductive output when species density was equal, but when molly density was greater, pupfish reproductive output was reduced. We concluded that conditions promoting a larger pupfish population would cause molly to decline in number. Pupfish were observed to outnumber molly in spring-pools with little emergent vegetation and an outflow channel dominated by pupfish. Rehabilitation of an Ash Meadows spring system such that these environmental conditions were met resulted in a spring-pool that had been dominated by sailfin molly before rehabilitation to one dominated by pupfish with an increase in pupfish population size after rehabilitation.