| dc.description.abstract | Spiders are sentinel species, organisms that serve to map the bioavailable fraction of contaminants in an ecosystem by retaining contaminants in their tissues. For example, spiders in the families Tetragnathidae and Araneidae are frequently used as sentinels of mercury (Hg) contamination of aquatic ecosystems. Spiders are frequently preserved in alcohol prior to contaminant analysis but the impact of alcohol preservation on Hg concentrations in spiders has not been assessed. The objective of the present study was to determine the effect of 95% ethanol preservation on Hg concentrations in tissues of spiders in the families Tetragnathidae and Araneidae. This present study was divided into two phases, a short-term study and a long-term study. In both studies, the spiders were collected along the shoreline of waterbodies using nets and gloved hands. In the short-term study, Tetragnathids were collected from Lake Weatherford, and the Araneids were collected from Eagle Mountain Lake. In the long-term study, both Tetragnathids and Araneids were collected from the Clear Fork of the Trinity River. After collection, spiders from each study were either preserved in 95% ethanol or frozen prior to analysis for total Hg using a Direct Mercury Analyzer. Mercury concentrations in spiders form the short-term and long-term study were examined after 40 days and two years, respectively. In both the short-term and long-term studies, preservation method had no significant effects on mercury concentrations in Tetragnathids, but Hg concentrations were significantly in Araneids preserved in 95% ethanol were significantly higher than in those that were frozen. We hypothesize that ethanol preservation may lead to an increase in Hg concentration because ethanol extracts lipids from the spider tissues, decreasing their body weight without changing the absolute of Hg within their tissues. The present study suggests that ethanol preservation may affect Hg concentrations in spider taxa with a high percentage of lipids in their tissues. | |
