Shellfish may improve water quality in north Florida estuary

  • A protected estuary in north Florida comprised of the Guana Lake and Guana River is showing signs of pollution.
  • Home to incredibly rich marshes, mounds of mussels and live oyster reefs, scientists are hoping shellfish might be a way to filter that pollution in an effort to restore water quality.
  • A $595,000 grant will fund a massive multi-agency, a multi-year effort led by a scientist at the University of Florida Institute of Food and Agricultural Sciences.

FLORIDA – Shellfish are vital to keeping estuaries healthy. They efficiently feed on and filter nutrients and chemical contaminants, which helps keep the water clear for underwater grasses and other aquatic life.

[inlinetweet prefix=”” tweeter=”” suffix=””]Recognizing the cleaning ability of shellfish, a team of scientists from the University of Florida and elsewhere hopes to restore a polluted estuary in north Florida.[/inlinetweet]

A view of the Guana River peninsula.

Ashley Smyth, a scientist at the University of Florida Institute of Food and Agricultural Sciences Tropical Research and Education Center, and colleagues have been awarded a $595,000 grant to study the role shellfish can take to mitigate water quality issues in the Guana Lake and Guana River in St. Johns County. Smyth will serve as lead principal investigator in a multi-step, multi-year research project.

“Normally, this would be a pristine area of nature, but nitrogen and other nutrients have found their way into the system, leading to algal blooms and low oxygen in the water, with consequences for oysters and mussels,” said Smyth, an assistant professor of biogeochemistry in the UF/IFAS department of soil and water sciences.

This protected estuary is home to rich marshes, mounds of mussels and live oyster reefs. The estuary’s dam separates the river from Guana Lake. Over the last few years, a community-supported, multi-agency monitoring effort revealed that the estuary is showing signs of pollution.

“The heart of all of this is that there is a water quality problem causing deterioration in the ecosystem that people enjoy, where wildlife thrives, and that benefits the environment and economy. This research will help the community develop restoration and management plans,” said Smyth.

A view of the marses and oyster beds on the Guana River.

The three-year grant, which begins in April, will accomplish various tasks:

  • Assess and collect data about the water quality and health of shellfish in the Guana River Estuary.
  • Identify how changes in land use have produced nitrogen spikes into the waterway.
  • Assess how shellfish can improve water quality and benefit the local economy.
  • Engage stakeholders and community groups throughout the project to encourage practices that will reduce nutrient input into the estuary.
  • Engage stakeholders and outlying communities in proactive estuary reform.

Researchers aim to develop a restoration and management plan that stakeholders can buy into and improves the estuary. Doing so may prevent legislative mandated action required by the U.S. Environmental Protection Agency that oversees the maximum amount of nutrients that can be in the system. Currently, the water quality issues are related to excess nutrients.

Funding for the project, which is provided by the National Estuarine Research Reserve System (NERRS) Science Collaborative, is designated for research to inform management of the Guana Tolomato Matanzas National Estuarine Research Reserve. The reserve is one of 29 coastal sites that are part of the National Estuarine Research Reserve system throughout the United States.

The Guana River estuary consists of Guana Lake, which skirts the seaside community of Ponte Vedra Beach in St. Johns County, and the Guana River, which is separated from the lake by a dam.

Collaborating with Smyth’s team from UF are Nikki Dix, research director at the Guana Tolomato Matanzas National Estuarine Research Reserve and Kaitlyn Dietz, coastal training coordinator.

“The project outcomes will contribute significantly to future resource management decisions by quantifying the interaction between stressors, the ecological services that oysters provide, and the costs and benefits of enhancing oyster harvesting and aquaculture in the Guana River,” according to a statement in the reserve’s letter of support.


By: Lourdes Rodriguez, 954-577-6363 office, 954-242-8439 mobile,

The mission of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS)
is to develop knowledge relevant to agricultural, human and natural resources and to make
that knowledge available to sustain and enhance the quality of human life. With more than
a dozen research facilities, 67 county Extension offices, and award-winning students and faculty
in the UF College of Agricultural and Life Sciences, UF/IFAS brings science-based solutions
to the state’s agricultural and natural resources industries, and all Florida residents. | @UF_IFAS


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Posted: February 17, 2021

Category: Natural Resources, SFYL Hot Topic, UF/IFAS, UF/IFAS Research, Water
Tags: Ashley Smyth, Florida Sea Grant, Guana Lake, Guana River, Guana Tolomoto Matanzas National Estuarine Research Reserve, National Estuarine Research Reserve System, Shellfish, Soil And Water Sciences, Soil And Water Sciences Department, St. Johns County, U.S. Environmental Protection Agency, UF/IFAS Tropical Research And Education Center, Water Quality

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