Food Web Structure and Potential Community-level interactions in a reconstructed desert wetland, San Solomon Ciénega, Balmorhae State Park, Texas

Authors: Sam Hamontree, Gary P. Garrett, Raelynn Deaton, Chad C. Hargrave

Year: 2010 (xlii)

Abstract

In an attempt to conserve two endangered fishes (Cyprinidon elegans and Gambusia nobilis), the Texas Parks and Wildlife Department (TPWD) restored a critical desert wetland habitat by creating the San Solomon Ciénega at Balmorhea State Park in 1996 through a cooperative effort among private, state, and federal entities. This re-creation of a desert wetland habitat within the boundaries of the original, natural ciénega provided critical habitat necessary for survival of desert wetland biota. As a result, the native fish fauna, including Cyprinidon elegans and Gambusia nobilis, have flourished, and this location now provides a natural habitat with the largest known concentration of these taxa. It is believed that the primary benefit of the San Solomon Ciénega to the survival of these endangered fishes is the creation of a ‘natural’ habitat with viable ecosystem-level processes that promote population stability. However, there have been no concerted efforts to document the community and ecosystem dynamics of this system. Herein, we describe seasonal gut content and stable isotope data for the fish community in San Solomon Ciénega. In general, food resources for the fishes in these ciénega are relatively consistent across season. Algae is an important food resource for C. elegans. Both G. nobilis and G. geiseri (an invasive) are linked to terrestrial and aquatic invertebrates. These two species have high diet overlap and are likely to compete for limiting food in these systems. Astyanax mexicanus (also invasive) is largely predatory feeding on aquatic and terrestrial invertebrates as well as small fishes. This species also play an important role in limiting abundance of native fishes through predation or competition.