About the Authors

Kevin A. Thorn

kathorn@usgs.gov

Affiliation U.S. Geological Survey, Denver Federal Center, MS 408, Denver, Colorado, 80225–0046, United States of America

Larry G. Cox

Affiliation U.S. Geological Survey, Denver Federal Center, MS 408, Denver, Colorado, 80225–0046, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: KAT. Performed the experiments: LGC. Analyzed the data: KAT LGC. Contributed reagents/materials/analysis tools: KAT LGC. Wrote the paper: KAT LGC.