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Press Release for Tuesday, September 11, 2018

St. Johns River’s Dissolved Oxygen Levels Show Improvement for First Time in Years

Media Contact: Joanna Norris, Director
Department of Public Relations
(904) 620-2102

The eleventh annual State of the River Report, an analysis of the health of the Lower St. Johns River Basin, reveals several areas of improvement, some the first time in years, but shows trends that some indicators have worsened, suggesting that continued monitoring and research of the river are needed.


Trends from the latest River Report highlight several positives, including dissolved oxygen levels in the tributaries changing for the better in the first time in many years and improving total phosphorus levels in the saltwater reach of the river's mainstem. Other improvements to the mainstem include decreased concentrations of heavy metals, such as arsenic, cadmium, copper, lead, nickel, silver and zinc, are also getting better in the mainstem, while conditions for three critical wildlife species-the bald eagle, wood stork and Florida manatee-have also improved.


"Dissolved oxygen in the tributaries is complex and while the levels have tended to be critically low at times, particularly during the hot summers, they are up now," said Dr. Gerry Pinto, associate research scientist at the Jacksonville University Marine Science Research Institute. "Each tributary is different because of the surrounding land use, flow rate, depth and salinity, which can vary depending on the time of day. But the good news is that in the last three years, minimum dissolved oxygen levels in the tributaries have been improving and most recently, for the first time, exceeded the freshwater criterion and are on par with the marine/estuarine criterion."


Although there are some positive indicators, there are still some concerns for the river's health. Over the last 20 years, salinity has gradually risen and is expected to continue its increase, with growing potential negative impacts on submerged aquatic vegetation and the aquatic life that depends upon it for habitat and food sources.


Nonnative species have also risen to 87 total species, up from 57 in 2008, with a key concern of spreading lionfish as well as Cuban treefrogs and their impacts on our native ecosystem. Plus, wetlands continue to be lost to development and while the losses tend to have the greatest impacts locally, those impacts aren't altogether realized from a regional perspective.


"Improvement in dissolved oxygen in the tributaries is encouraging. But the severity of this year's algal blooms tells us that nutrient levels remain too high. Even though phosphorus levels are improving in the long-term, short-term and localized events still boost algae growth," said Dr. Radha Pyati, former UNF chemistry chair and professor who is now dean of the College of the Sciences and Mathematics at West Chester University in Pennsylvania. Pyati will continue to be a part of the research team for the annual report.


Other indicators remain largely unchanged. For example, chlorophyll a, an indicator of harmful algal blooms, remains elevated and widespread, aside from limited data. Fecal coliform levels in the tributaries also are significantly above both previously used and newly developed water-quality criteria, while submerged aquatic vegetation experienced recent regrowth; the long-term trend is uncertain, and the low number of sampling sites increases this uncertainty. Additionally, the River Report shows that most finfish and invertebrate species aren't in danger of overfishing, with the exception of channel and white catfish, which both have the potential to be overfished in the near future.


This year's River Report includes a special section on applications of the Report to K-12 students in Duval County Public Schools, providing an important resource for teachers, such as lesson plans, to make crucial connections between science and the students' environment, which helps make science more concrete and engages student in real-world problem solving. Additionally, materials can be modified to support science learning at multiple curricular levels.


"We're excited help teachers use these new resources to help them connect the local watershed to STEM curricula in order to make it more relevant and engaging to their students," said Dr. Brian Zoellner, UNF assistant professor in the Department of Foundations and Secondary Education.


A presentation on the findings will take place today, Friday, Sept. 14, during the 2018 Environmental Symposium, "Investment, Innovation and Action-Leading the Way to a Sustainable Future," scheduled from 8 a.m. to 5 p.m. at the Adam W. Herbert University Center, Building 43, in the Grand Banquet Hall, Room 1044, on the UNF campus. The River Report and a brochure, a quick reference guide on river health and ways the public can help the river, will be available at as well.


The annual symposium, sponsored by the Environmental Protection Board of the City of Jacksonville and the UNF Environmental Center, brings together members of the community to interact with the regular agencies responsible for developing and implementing environmental policy.


The State of the River Report is a collaboration among UNF, JU and Florida Southern College and is supported by the Environmental Protection Board. UNF River Report team members include Pyati, Zoellner and Dr. Charles Closmann, UNF associate professor of history. JU team members include Pinto; Dr. Nisse Goldberg, professor of biology/marine science and chair of Biology and Marine Science; Dr. Anthony Ouellette, professor of Biology; and Dr. Gretchen Bielmyer-Fraser, associate professor of chemistry; and Dr. An-Phong Le, associate professor of chemistry at Florida Southern College.


The Marine Science Research Institute at Jacksonville University is the premier biological and environmental research and education facility on the St. Johns River. The two-story, 32,000-square-foot "certified-green" building has classrooms, laboratories, offices for the St. Johns Riverkeeper and the Florida Fish and Wildlife Conservation Commission, and areas for teaching Duval County public school students. For more information, visit


The mission of the UNF Environmental Center, founded in 2004, is to establish, develop and support cross-disciplinary education and research related to the environment. The center fosters programs for students, faculty and staff to pursue environmental activities through academics, research and extracurricular activities. For more information, visit the Environmental Center Website.