TP3 Linking Aquatic Toxicology with Ecosystem Indicators
Ballroom G, Level 4
2:10 PM - 5:30 PM, Tuesday, 11 November 2003
Chair: Anderson, Susan ,
(272) Metal partitioning to metal sensitive subcellular fractions as a diagnostic of species vulnerability.
Cain, D1, Carter, J1, Hornberger, M1, Luoma, S1, Wallace, W2, 1 U.S. Geological Survey, Menlo Park, CA, USA2 The College of Staten Island/CUNY, Staten Island, NY, USA
ABSTRACT- Mechanistically-based diagnostic tools can be used to support assessments of ecological effects of contaminants, and to monitor the efficacy of remediation. Recent studies have compared subcellular distributions of metals among stream insects as a way to account for inter-specific differences in metal tolerance. Studies in the Clark Fork river indicated that the vulnerability of different taxa to metal exposure was linked to differences in the concentration of Cu (and other metals) associated with an operationally defined Metal-Sensitive Compartment (MSC includes metals associated with organelles and with cytosolic proteins other than metallothionein). Taxa with elevated Cu concentrations in the MSC were absent from sites closest to the inoperative mining/smelting complex. Copper concentrations in water and in macroinvertebrates have declined, particularly since 1997, in the upper 70 Km of the river, where some remediation has occurred, although exposures remain well above those in uncontaminated tributaries, in at least some years. Bioassesments, based upon an index of biointegrity, conclude that recovery has occurred at some of these sites. Closer inspection of the data show that the taxa that appeared to be most vulnerable to metals have not reappeared, even though populations that could colonize the sites are established in adjacent tributaries. These results suggest that metal exposures and/or other environmental stressors are still limiting the establishment of these taxa, and that vulnerable species, defined by metal bioaccumulation/detoxification characteristics, may be the most sensitive indicators of metal effects in such streams.
Key words: species sensitivity, metals, detoxification, ecological effects