DRIVERS OF CONTINENTAL SCALE EUTROPHICATION AND OXYGEN DECLINES IN U.S. ESTUARIES

The National Estuarine Research Reserve System's (NERRS) System-Wide Monitoring Program (SWMP), established in 1995, aims to measure short-term variability and long-term trends in water quality, meteorological conditions, biological systems, and land-use/land-cover in estuarine ecosystems. This study analyzed SWMP water quality and meteorological data from 99 stations across 28 Reserves along U.S. coasts, including the Great Lakes, covering 10 to 23 years. The findings indicate widespread eutrophication in estuaries, with significant increases in chlorophyll-a at nearly 70% of sites. Additionally, almost half of the sites show significant declines in dissolved oxygen, and over 60% report significant temperature increases. To explore potential drivers of changes in chlorophyll-a and dissolved oxygen, we used model selection and averaging techniques on Linear Mixed Effects models for each response variable. The models suggest that increases in dissolved phosphorus and turbidity, as well as decreases in ammonia and trophic state, are linked to rising chlorophyll-a concentrations while increasing temperatures and chlorophyll-a trends likely contribute to decreases in dissolved oxygen. Notably, while dissolved oxygen concentrations are declining, there is little change in the extent of hypoxic conditions (DO < 2mg/L). These results highlight the importance of developing effective strategies to protect the ecological health of estuarine systems in the face of environmental change.

Presentation Preference: Oral

Primary Presenter: Kaitlin Reinl, University of Wisconsin - Madison (kreinl@wisc.edu)

Authors:

Kaitlin Reinl, Lake Superior National Estuarine Research Reserve, University of Wisconsin - Madison Division of Extension  (kreinl@wisc.edu)

Robert Dunn, North Inlet-Winyah Bay National Estuarine Research Reserve, Baruch Marine Field Laboratory University of South Carolina  (robert@baruch.sc.edu)

Kimberly Cressman, Catbird Stats, LLC  (kim@catbirdstats.com)

Theophilos Collins, Waquoit Bay National Estuarine Research Reserve  (theophilos.j.collins@mass.gov)

Jennifer Debose, Grand Bay National Estuarine Research Reserve  (jennifer.debose@dmr.ms.gov)

Carl Friedrichs, Chesapeake Bay National Estuarine Research Reserve in Virginia, Virginia Institute of Marine Science  (Carl.Friedrichs@vims.edu)

Alicia Helms, South Slough National Estuarine Research Reserve, Oregon Department of State Lands  (alicia.r.helms@dsl.oregon.gov)

Christopher Kinkade, NOAA NOS Office for Coastal Management  (chris.kinkade@noaa.gov)

Julie Krask, North Inlet-Winyah Bay National Estuarine Research Reserve, Baruch Marine Field Laboratory University of South Carolina  (julie@baruch.sc.edu)

David Parrish, Chesapeake Bay National Estuarine Research Reserve in Virginia, Virginia Institute of Marine Science  (parrishd@vims.edu)

Hannah Ramage, Lake Superior National Estuarine Research Reserve, University of Wisconsin - Madison Division of Extension  (hannah.ramage@wisc.edu)

Justin Ridge, North Carolina National Estuarine Research Reserve, North Carolina Department of Environmental Quality Division of Coastal Management  (justin.ridge@ncdenr.gov)

Denise Sanger, ACE Basin National Estuarine Research Reserve, South Carolina Department of Natural Resources  (sangerd@dnr.sc.gov)

Jacob Cianci-Gaskill, Old Woman Creek National Estuarine Research Reserve, Ohio Department of Natural Resources  (jacob.cianci-gaskill@dnr.ohio.gov)

Nicole Dix, Guana Tolomato Matanzas National Estuarine Research Reserve, Florida Department of Environmental Protection & University of North Florida  (Nikki.Dix@dep.state.fl.us)

Thomas Grothues, Jacques Cousteau National Estuarine Research Reserve, Rutgers University  (grothues@marine.rutgers.edu)

Steven McMurray, Old Woman Creek National Estuarine Research Reserve, Ohio Department of Natural Resources  (steven.mcmurray@dnr.ohio.gov)

Christopher Peter, Great Bay National Estuarine Research Reserve, New Hampshire Fish and Game  (christopher.r.peter@wildlife.nh.gov)

Sylvia Yang, Padilla Bay National Estuarine Research Reserve, Washington State Department of Ecology  (syang@padillabay.gov)