title: Toxicity of Chromium (VI) to Two Mussels and an Amphipod in Water-Only Exposures With or Without a Co-stressor of Elevated Temperature, Zinc, or Nitrate.
abstract: The objectives of the present study were to develop methods for propagating western pearlshell (Margaritifera falcata) for laboratory toxicity testing and evaluate acute and chronic toxicity of chromium VI [Cr(VI)] to the pearlshell and a commonly tested mussel (fatmucket, Lampsilis siliquoidea at 20 °C or in association with a co-stressor of elevated temperature (27 °C), zinc (50 µg Zn/L), or nitrate (35 mg NO3/L). A commonly tested invertebrate (amphipod, Hyalella azteca) also was tested in chronic exposures. Newly transformed pearlshell (~1 week old) were successfully cultured and tested in acute 96 h Cr exposures (control survival 100%). However, the grow-out of juveniles in culture for chronic toxicity testing was less successful and chronic 28-day Cr toxicity tests started with 4 month-old pearlshell failed due to low control survival (39-68%). Acute median effect concentration (EC50) for the pearlshell (919 µg Cr/L) and fatmucket (456 µg Cr/L) tested at 20 °C without a co-stressor decreased by a factor of > 2 at elevated temperature but did not decrease at elevated Zn or elevated NO3. Chronic 28-day Cr tests were completed successfully with the fatmucket and amphipod (control survival 83-98%). Chronic maximum acceptable toxicant concentration (MATC) for fatmucket at 20 °C (26 µg Cr/L) decreased by a factor of 2 at elevated temperature or NO3but did not decrease at elevated Zn. However, chronic MATC for amphipod at 20 °C (13 µg Cr/L) did not decrease at elevated temperature, Zn, or NO3. Acute EC50s for both mussels tested with or without a co-stressor were above the final acute value used to derive United States Environmental Protection Agency acute water quality criterion (WQC) for Cr(VI); however, chronic MATCs for fatmucket at elevated temperature or NO3and chronic MATCs for the amphipod at 20 °C with or without elevated Zn or NO3were about equal to the chronic WQC. The results indicate that (1) the elevated temperature increased the acute Cr toxicity to both mussel species, (2) fatmucket was acutely more sensitive to Cr than the pearlshell, (3) elevated temperature or NO3increased chronic Cr toxicity to fatmucket, and (4) acute WQC are protective of tested mussels with or without a co-stressor; however, the chronic WQC might not protect fatmucket at elevated temperature or NO3and might not protect the amphipod at 20 °C with or without elevated Zn or NO3.
authors.affiliation: United States Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO, 65201, USA. nwang@usgs.gov.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.affiliation: United States Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO, 65201, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Kunz
authors.affiliation: United States Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO, 65201, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ivey
authors.affiliation: United States Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, MO, 65201, USA.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ingersoll
authors.affiliation: Department of Biology, Missouri State University, 901 South National, Springfield, MO, USA.
authors.forename: M Christopher
authors.initials: MC
authors.lastname: Barnhart
authors.affiliation: Department of Biology, Missouri State University, 901 South National, Springfield, MO, USA.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Glidewell
mesh_terms: D033304:Amphipoda / Q000502:physiology*; D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D002857:Chromium; D006358:Hot Temperature; D009566:Nitrates / Q000633:toxicity*; D013312:Stress, Physiological; D036401:Toxicity Tests, Chronic; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015032:Zinc / Q000633:toxicity*
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D002857:Chromium; D015032:Zinc