Barbara C. Scudder

Effects of copper on development of the fathead minnow, Pimephales promelas Rafinesque

Abstract Embryos of the fathead minnow, Pimephales promelas Rafinesque, were exposed to total copper concentrations (Cu T ) of 0.6, 61, 113, 204, 338 and 621 μg/l from 5 to 10 h post-fertilization through 2 days post-hatch. A decrease in hatching time was observed with increasing total copper concentration but there was no decrease in embryonic developmental rate. Therefore, embryos hatched at earlier stages of development. Significant ( P ≤ 0.05) declines in percent survival and percent total hatch were observed at 621 μg/l Cu T ) but not at 338 μg/l Cu T or lower concentrations. The percentage of embryos with abnormalities was greater at 338 and 621 μg/l Cu T than at 204 μg/l Cu T and lower concentrations. Individuals exposed to copper during early development were then exposed to the same test concentrations for 28 days post-hatch. Survivors at 113 through 338 μg/l Cu T were at earlier stages of development than were control fish. The percentage of fish surviving decreased with increasing copper concentration over the range 61 through 204 μg/l Cu T . The percentage of fish surviving at 204 μg/l Cu T was not significantly different from that at 338 μg/l Cu T , and there were no survivors at 621 μg/l Cu T . Surviving larvae at all copper concentrations from 61 through 621 μg/l Cu T showed decreased length, weight and coefficient of condition compared to controls. The percentage of larvae with abnormalities increased significantly with increasing copper concentration. The calculated 96-h LC 50 (larval stage) was 250 μg/l Cu T and the 28-day LC 50 (larval stage) was approximately 123 μg/l Cu T .

Trace elements in Corbicula fluminea from the San Joaquin River, California.

(i) Trace element concentrations in soft tissue of the benthic bivalve, Corbicula fluminea, from the San Joaquin River and its major tributaries were examined during the primary irrigation season in relation to the spatial variation in concentrations of major, minor and trace constituents in riverwater and sediments. (ii) Selenium concentrations in Corbicula from perennial flow reaches of the San Joaquin River and its major tributaries varied directly with the solute (less than or equal to 0.45 microns) Se concentrations of riverwater. Elevated concentrations occurred in clams from sites with substantial discharge originating as subsurface drainage and irrigation return flows. Both tissue and solute Se concentrations declined from June through the end of the primary irrigation season. (iii) Arsenic concentrations in Corbicula from perennial flow reaches of the San Joaquin River varied directly with the HNO3-extractable (pH 2) As:Fe ratio of suspended matter, providing evidence that sorption to oxyhydroxide surfaces is an important control on the biological availability of As. However, Corbicula from several tributaries draining alluvium derived from the Sierra Nevada had lower As concentrations than would be predicted by the relation developed for perennial flow sites of the San Joaquin River. Arsenic concentrations in Corbicula from the Tuolumne and Merced Rivers and upstream reaches of the San Joaquin River were higher than in clams from the downstream perennial flow reaches of the San Joaquin River. Concentrations of As in clams from downstream perennial flow reaches of the San Joaquin River increased from June through the end of the primary irrigation season. (iv) Mercury concentrations in Corbicula were elevated in upstream reaches of the San Joaquin River, in the Merced and Tuolumne Rivers, and in tributaries draining the Coast Ranges. Mean Cd and Cu concentrations in Corbicula were elevated in the Merced and Tuolumne Rivers, Orestimba Creek and a perennial flow reach of the San Joaquin River which receives water directly from the Delta Mendota Canal. Concentrations of Ni in clams from the San Joaquin River decreased downstream of the Delta Mendota Pool. (v) Boron and Mo were not accumulated by Corbicula despite high solute concentrations (means as high as 2960 micrograms Bl-1 and 9 micrograms Mol-1) in riverwater during the primary irrigation season. This bivalve may not be an appropriate bioindicator of B and Mo enrichment. Concentrations of Cr, Pb, Ag, V and Zn in Corbicula exhibited little geographic variability in the drainage. (vi) Regression analysis revealed no clear evidence of synergistic or antagonistic interactions among As, Cd, Cu, Hg, Ni and Se in their uptake by Corbicula.