DESANTISLAND

South Florida estuaries warming faster than Gulf of Mexico, global ocean, USF research shows

Possible causes include evaporation, water capacity and residence time (the amount of time water spends in an estuary). No single factor has been identified as dominant

Peer-Reviewed Publication

University of South Florida

 

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Chuanmin Hu, University of South Florida

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Credit: USF

TAMPA. (Aug. 7, 2024) – Sea surface temperatures are on the rise around the world, but the problem is pronounced in South Florida, according to a series of studies published by researchers at the University of South Florida College of Marine Science.

Estuaries in South Florida have experienced rapid warming over the past two decades, including a record-breaking marine heat wave in 2023.

Using satellite data, the researchers found that sea surface temperatures in four estuaries in South Florida have risen faster than sea surface temperatures globally and in the Gulf of Mexico. The findings, published in Environmental Research Letters and Estuaries and Coasts, paint a troubling picture for the marine life that calls Florida home.

“The temperatures in South Florida estuaries are not only rising faster than the global average, but also faster than temperatures in the open Gulf of Mexico,” said Chuanmin Hu, professor of physical oceanography at the University of South Florida and co-author of the recent papers. “We even saw more of a response within the estuaries to last year’s marine heat wave.”

Over the past two decades, sea surface temperatures in Florida Bay, Tampa Bay, St. Lucie Estuary and Caloosahatchee River Estuary rose around 70 percent faster than the Gulf of Mexico and 500 percent faster than the global oceans, according to the authors. The temperatures are expected to take a toll on marine life.

Estuaries are nurseries where many marine animals begin their lives. South Florida’s estuaries are home to critical habitats such as seagrass meadows, and adjacent waters in the Florida Keys are home to world-renowned coral reefs. These may be impacted by rising water temperatures.

“Algae, seagrass and coral are all sensitive to temperature changes,” Hu said. “Algae prefer warm water, which can increase the size and frequency of blooms. Meanwhile, seagrass and coral undergo stress if the water gets too warm.”

The researchers hope to partner with colleagues at the Florida Fish and Wildlife Conservation Commission and the National Oceanic and Atmospheric Administration to explore the potential impacts of water temperatures on seagrass and coral populations in South Florida.

The researchers speculated on possible causes for the high rate of warming in South Florida’s estuaries, including evaporation, water capacity and residence time (the amount of time water spends in an estuary). No single factor has been revealed as dominant.

Ongoing research by Hu and Jing Shi, a doctoral student in Hu’s lab and first author of the papers, will investigate another peculiar observation: the accelerated warming seen in South Florida’s estuaries has not been detected in other estuaries across the region.

“Not every estuary around the Gulf of Mexico is behaving this way,” Hu said. “These temperature changes appear unique to the estuaries of South Florida.”

The next question, Hu said, is how long this faster warming in South Florida will be sustained.

“We expect the rate of warming to eventually balance with the open Gulf of Mexico,” he said. “We just don’t know when that will happen.”

This research was supported by a grant from the NASA Water Resources Program and a USF presidential fellowship.

Temperatures in South Florida estuaries are rising faster than those in the Gulf of Mexico and global oceans.

Credit

USF

This high-resolution image from the ECOSTRESS dataset depicts sea surface temperatures around the Florida Keys in response to the 2023 marine heat wave. Courtesy of Jing Shi.

This image from the MODIS dataset shows surface water temperatures off Southwest Florida in July 2023 is mostly two degrees Celsius warmer than the previous 20 years in response to the 2023 marine heat wave. Courtesy of Jing Shi.

Credit

Jing Shi, University of South Florida

About the University of South Florida

The University of South Florida, a high-impact research university dedicated to student success and committed to community engagement, generates an annual economic impact of more than $6 billion. With campuses in Tampa, St. Petersburg and Sarasota-Manatee, USF serves approximately 50,000 students who represent nearly 150 different countries. U.S. News & World Report has ranked USF as one of the nation’s top 50 public universities for five consecutive years, and this year USF earned its highest ranking ever among all universities public or private. In 2023, USF became the first public university in Florida in nearly 40 years to be invited to join the Association of American Universities, a prestigious group of the leading universities in the United States and Canada. Through hundreds of millions of dollars in research activity each year and as one of the top universities in the world for securing new patents, USF is a leader in solving global problems and improving lives. USF is a member of the American Athletic Conference. Learn more at www.usf.edu. 

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Journal

Estuaries and Coasts

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

Temperature Response of South Florida Estuaries to the 2023 Heatwave