T3 PM Aquatic Ecotoxicology (Part 2)
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in Ballroom 3

(BRI-1118-264598) The Effects of Elevated Total Dissolved Solids on Fertilization and Water Hardening of Salmonid Embryos.

Brix, K^{1, 2}, Curry, H², Kasper, A², Gerdes, R², Grosell, M², ¹ EcoTox, Key Biscayne, FL, USA² RSMAS, Miami, FL, USA

ABSTRACT- We investigated the effects of elevated Total Dissolved Solids (TDS, primarily as Ca²⁺ and SO₄^2-) on the fertilization success and water hardening of Arctic grayling (Thymallus arcticus) and Dolly Varden (Salvelinus malma) embryos. The high TDS water is characteristic of many hard rock mine wastewater effluents that may discharge to environments where salmonids spawn. Our studies indicate fertilization success when exposed to elevated TDS is highly variable. For Arctic grayling, EC20s for fertilization success ranged from 202 to >1381 mg l^-1 TDS, while for Dolly Varden EC20s were all >1700 mg l^-1, but some tests exhibited inverse dose response relationships. Possible reasons for the high variability include natural biological variability and artifacts of the test methods employed. No significant influx of Na⁺, K⁺, Mg²⁺ and Cl^- was observed during water hardening. Transport of Ca²⁺ into eggs was observed at all concentrations tested including the control while SO₄^2- transport only occurred at elevated ambient SO₄^2- concentrations. Elevated TDS also had a direct impact on water transport into the eggs, with an approximate 50% reduction in water uptake at 1800 mg l^-1 TDS. The ecological significance of this reduced water hardening on egg survival and hatchability is unknown.

Key words: total dissolved solids