You are here:
Diverging fish biodiversity trends in cold and warm rivers and streams across the United States
Citation:
Rumschlag, S., B. Gallagher, R. Hill, R. Schaefer, T. Schmidt, T. Woods, D. Kopp, M. Dumelle, J. Rohr, F. De Laender, J. Hoffman, D. Carlisle, J. Behrens, R. Lepak, D. Jones, AND Mike Mahon. Diverging fish biodiversity trends in cold and warm rivers and streams across the United States. Minnesota American Fisheries Society, St. Cloud, MN, February 11 - 13, 2025. https://doi.org/10.23645/epacomptox.29546660
Impact/Purpose:
Documenting trends of fish biodiversity is challenging because biomonitoring often has limited spatial, temporal, and taxonomic scopes. The National Aquatic Resource Surveys (NARS) is a major national program aimed at understanding the state of the nation’s waters. NARS provides critical data of unparalleled scope that is capable of addressing this gap. We joined data from NARS and USGS BioData to document trends in fish assemblages in rivers and streams over 30 years across the contiguous U.S. We found diverging trends in fish assemblages occupying cold and warm streams. In cold streams, fish abundance and richness declined by 20.7% and 13.3% per decade. In warm streams, fish abundance and richness increased by 27% and 5.5% per decade. Warming waters and changes in introduced fish were associated with increased rates of degradation to local fish biodiversity. The current work demonstrates approaches to using NARS data to address mechanism of national-scale biodiversity trends and provides motivation and tools to generate subpopulations of fish by temperature.
Description:
Freshwater fish in the United States are at risk from changing stream temperatures and introduced fish, but effects across broad spatial extents remain unclear. We analyzed biodiversity (abundance, richness, uniqueness, functional diversity) of 389 species across 27 years and 2992 sites using biomonitoring datasets from USGS and USEPA. Biodiversity diverged across cold and warm streams across the United States. In cold streams, fish abundance and richness declined by 20.7% and 13.3% per decade, respectively, and uniqueness increased. Disturbance-sensitive periodic fish increased, and disturbance-tolerant opportunists decreased. In warm streams, fish abundance and richness increased by 27% and 5.5% per decade, respectively, and communities homogenized. Opportunistic fish replaced periodic fish. Interactions between warming and introduced fish were associated with increased rates of degradation to local fish biodiversity. This work provides motivation to conduct additional analyses with Minnesota state-level partners and datasets to evaluate how these trends vary state-by-state, to identify which fish species and assemblages are most at risk to changes, and to anticipate how management might play a role in supporting fish assemblages in the face of climate change and species introductions. This abstract neither constitutes nor necessarily reflects US EPA policy.
URLs/Downloads:
DOI: Diverging fish biodiversity trends in cold and warm rivers and streams across the United States
PRESENTATION.PDF (PDF, NA pp, 2494.255 KB, about PDF)