Mercury and selenium concentrations in fishes of the Upper Colorado River Basin, southwestern United States: A retrospective assessment

PLoS One. 2020 Jan 13;15(1):e0226824. doi: 10.1371/journal.pone.0226824. eCollection 2020.

Abstract

Mercury (Hg) and selenium (Se) are contaminants of concern for fish in the Upper Colorado River Basin (UCRB). We explored Hg and Se in fish tissues (2,324 individuals) collected over 50 years (1962-2011) from the UCRB. Samples include native and non-native fish collected from lotic waterbodies spanning 7 major tributaries to the Colorado River. There was little variation of total mercury (THg) in fish assemblages basin-wide and only 13% (272/1959) of individual fish samples exceeded the fish health benchmark (0.27 μg THg/g ww). Most THg exceedances were observed in the White-Yampa tributary whereas the San Juan had the lowest mean THg concentration. Risks associated with THg are species specific with exceedances dominated by Colorado Pikeminnow (mean = 0.38 and standard error ± 0.08 μg THg/g ww) and Roundtail Chub (0.24 ± 0.06 μg THg/g ww). For Se, 48% (827/1720) of all individuals exceeded the fish health benchmark (5.1 μg Se/g dw). The Gunnison river had the most individual exceedances of the Se benchmark (74%) whereas the Dirty Devil had the fewest. We identified that species of management concern accumulate THg and Se to levels above risk thresholds and that fishes of the White-Yampa (THg) and Gunnison (Se) rivers are at the greatest risk in the UCRB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Environmental Monitoring
  • Fishes* / classification
  • Linear Models
  • Mercury / analysis*
  • Molar / chemistry
  • Retrospective Studies
  • Rivers / chemistry
  • Selenium / analysis*
  • Southwestern United States
  • Tissue Distribution

Substances

  • Mercury
  • Selenium

Grants and funding

Funding was provided by the Bureau of Land Management to TSS, the Environmental Health Mission Area of the USGS to TSS, and the commercial company, Trapper Mine Inc. offered funding to the Colorado Water Science Center. The funders did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.