Table 3.
Acute median effect concentrations (EC50s) and 95% confidence limits (CLs; in parenthesis) for 10 chemicals in the multi-species study with 5 species of mussels representing different tribes or families of freshwater mussels
| EC50 (95% CL) | ||||||
|---|---|---|---|---|---|---|
| Toxicant (Test no.) | Unit | Threeridge | Paper pondshell | Fatmucket | Washboard | Western pearlshell |
| Alachlor | mg/L | 1.2 (0.8–1.8)a | 6.7 (5.6–7.9) | 2.7 (2.5–2.8) | 5.7 (5.0–6.4)b | 15 (12–20) |
| Metolachlor | mg/L | 4.6 (3.0–7.1)a | 15 (12–18) | 20 (16–26) | 6.8 (6.6–7.1) | 29 (27–31) |
| Ammonia (total) | mg/L | 1.5 (1.1–2.0) | 2.1 (1.4–3.0) | 5.2c/11c | 5.1 (4.7–5.5) | 8.0 (7.7–8.4) |
| Chloride (1)d | mg/L | 1038 (808–1333) | 1657 (1346–2039) | 1897 (1850–1945) | 1398 (1169–1670) | 1576 (1391–1786) |
| Chloride (2) | mg/L | —e | — | 1944 (1773–2131) | — | — |
| Chloride (3) | mg/L | — | — | 2246 (2211–2281) | — | — |
| Chloride (4) | mg/L | — | — | 1893 (1751–2045)f | — | — |
| Chloride (5) | mg/L | — | — | 2092 (1910–2290)f | — | — |
| Potassium (1)d | mg/L | 31 (17–57) | 38 (35–42) | <56 | 48 (41–56) | <56 |
| Potassium (2) | mg/L | — | — | 46 (38–54) | — | 38 (37–39) |
| Sulfated | mg/L | 1338 (no CL)a, g | 2709 (2548–2880) | 2325 (2176–2485) | 2279 (2206–2355) | 1378 (1335–1422) |
| Chromium (VI) | μg/L | 233 (179–303)a | 213 (187–242) | 266 (224–316) | 138 (132–144) | 624 (603–647) |
| Copper (1) | μg/L | 11 (10–12) | 13 (11–15) | 48 (40–57) | 25 (24–26) | 36 (35–38) |
| Copper (2) | μg/L | 10 (8.2–13) | — | 35 (30–42) | — | — |
| Copper (3) | μg/L | — | — | 55 (47–64) | — | — |
| Nickel (1) | μg/L | 234 (207–264) | 676 (648–705) | 506 [350–731]h | 173 (165–181) | 269 (259–280) |
| Nickel (2) | μg/L | — | — | 350 (298–411) | — | — |
| Nickel (3) | μg/L | — | — | 445 (429–461) | — | — |
| Zinc | μg/L | 299 (205–438) | 520 (446–606) | 576 (507–654) | 566 (532–602) | 447 (97–502) |
The EC50 should be used with caution due to low (<90%) control survival. See text for details.
Only 45% mortality was observed in the highest test concentration (Supplemental Data, Table S4–1).
Values for fatmucket were from a previous study at pH 8.1 and 20 °C 8 (see details in text).
Chloride was tested as sodium chloride, potassium as potassium chloride, and sulfate as sodium sulfate (details in Table 2).
A dash (—) indicates that the chemical was not tested with that species.
Exposure solutions were prepared with a 30% series dilution (rather than 50% dilution in other tests).
No CL could be calculated due to inadequate partial effects (Supplemental Data, Table S4–6).
An EC50 could not be calculated due to no partial mortality (Supplemental Data, Table S4–9). The geometric mean of the bracketing concentrations with 0% and 100% mortality was calculated to obtain an estimated EC50. The 0% and 100% effect concentrations are provided in bracket as [0–100% effect concentration].