W7 AM Acclimation / Adaptation of Animals to Metals: Resistance, Tolerance, and Cost
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in 327-329

(CLE-1117-747533) Adaptation and acclimation of benthic macroinvertebrates to heavy metals increases susceptibility to novel anthropogenic stressors.

Clements, W¹, Kashian, D¹, Harrahy, E², Courtney, L³, ¹ Colorado State University, Fort Collins, CO, USA² Wisconsin Department of Natural Resources, Madison, WI, USA³ University of Colorado, Boulder, CO, USA

ABSTRACT- Populations exposed to heavy metals often exhibit enhanced tolerance compared to naive or unexposed populations. Although increased tolerance to low levels of metals is often protective of subsequent pulsed exposure, the physiological and genetic mechanisms responsible for tolerance may have specific costs. We conducted stream microcosm experiments designed to assess the tolerance and associated costs of macroinvertebrate communities exposed to heavy metals. Communities collected from reference and metal-impacted streams in Colorado were subsequently exposed to combinations of heavy metals and other biotic and abiotic stressors (reduced pH, UV-B radiation, predation by stoneflies). In all instances, organisms collected from metal-polluted streams were more tolerant of metals than naive organisms. However, despite greater tolerance to metals, assemblages from metal-polluted streams were more sensitive to UV-B radiation, acidification, and predation. Because of the ubiquitous nature of heavy metal pollution in Rocky Mountain streams, these results have significant implications for understanding interactions between heavy metals and other anthropogenic stressors. If increased susceptibility to novel stressors is widespread in metal-tolerant populations, it is likely these populations will be disproportionately affected by other anthropogenic stressors.

Key words: heavy metals, acclimation, Rocky Mountain streams