Summary

Description

Many springs associated with the Edwards Aquifer of Texas are inhabited by relict populations of neotenic salamanders in the genus Eurycea. This study was done to assess the water quality characteristics in habitat springs of Eurycea salamanders associated with various springs of the Edwards Aquifer. The goals of the study were to identify bioavailable contaminants associated with individual springs and to evaluate the effects of contaminants and sediment turbidity on the survival of springassociated salamanders. Collections of samples andor salamanders made from five habitat springs Barrow Hollow Springs, Barton Springs, Collapsed Bridge Springs, San Marcos Springs, and Stillhouse Hollow Springs from two counties in central Texas. Analyses were conducted to determine 1 the presence of organic contaminants in salamander habitat springs as determined with semipermeable membrane devices SPMDs, 2 survival effects for salamanders under incremental increases in sediment loads, and 3 relative sensitivities of salamanders to selected contaminants under controlled conditions in a laboratory setting. Measurable concentrations were found by SPMD determinations for 13 organochlorines, 5 polycyclic aromatic hydrocarbons PAHs, and 2 pyrethroid pesticides for the five habitat springs. Three types of sediment slurry tests single 24h pulse, three 8h pulses, and continuous presence of sediment did not produce large biomass changes in two salamander species. Polycyclic aromatic hydrocarbons PAHs in sediment at Barton Springs were sufficiently elevated to impact the amphipod Hyalella azteca, a food source of the endangered Barton Springs salamander Eurycea sosorum. Although results from preliminary acute toxicity tests presented in this study would indicate that Eurycea salamander species are similar to or less sensitive to tested contaminants as compared to fish species, the test results have to be regarded as preliminary because of the small number of salamanders and contaminants used for testing. Due to the lack of existing information of sublethal effects of contaminants on neotenic salamanders, regulatory protective measures such as water quality criteria, pesticide use restrictions, etc. should be conservative with respect to protection of Eurycea species from water or sedimentborne contaminants. Additionally, considerations should be given to protection of the habitat including the salamanders prey base.