Manatee Center Research Verifies Manatees Continue Visiting Fort Pierce

Moore’s Creek is a lifeline for Manatees seeking warmer, fresh water 

Fort Pierce Utilities Authority (FPUA) proudly announces the publication of a peer-reviewed scientific article that confirms manatees continue to rely on Fort Pierce’s Moore’s Creek as a passive thermal basin in the area immediately adjacent to FPUA’s Manatee Center, located at 480 North Indian River Drive, Fort Pierce, FL 34950.

The study, “Persistent long-term habitat use by Florida Manatees at Fort Pierce, Florida from 1997 to 2020,” explored the impact that decommissioning the old Henry D. King Power Plant had on the long-term habitat use of Florida manatees at Moore’s Creek from 1997 to 2020.  Historically, the power plant’s clean, warm water discharged into Moore’s Creek near the Fort Pierce Marina and created a ‘thermal refuge’ or artificial pocket of warm water which attracted manatees, especially during the winter months.  The power plant went offline in 1995 and was decommissioned in 2008, leaving manatee lovers and researchers alike wondering whether the loss of that thermal refuge affected the presence of manatees in the area.

Acting as Citizen Scientists, ‘Roving Naturalist’ volunteers at the Manatee Center devoted over 20 years and 7,000 hours to observing and counting manatees that visited Moore’s Creek. These observations, coupled by the addition of a Kilroy Continuous Water Monitoring System device in Moore’s Creek (an Ocean Research & Conservation Association device), led to a first-of-a-kind academic study exploring the impact of water temperatures and other environmental factors on manatees and Fort Pierce’s place in manatees’ habitat.

The study was conducted by Dr. Beth Brady, Senior Science and Conservation Associate at Save the Manatee Club, and featured original research from Manatee Center volunteers and Ms. Rachel Tennant, former Manatee Center Manager.  Co-authors and research partners include: Kim R. Love of K.R. Love Quantitative Consulting and Collaboration, Eric A. Ramos of Fundación Internacional para la Naturaleza y la Sustentabilidad and the University of Vermont, and Ryan Schloesser of Mote Marine Laboratory.  The researchers asked to what degree do manatees continue to occupy Moore’s Creek and how do environmental factors influence their occurrence in the creek?

The study’s results demonstrate that even after the power plant was decommissioned, manatees continued returning to Fort Pierce waterways because of  Moore’s Creek’s status as a ‘passive thermal basin.’ Fort Pierce waterways are unique because the surrounding system of canals, rivers, streams and estuaries leading to the Indian River Lagoon create passive thermal basins which are essentially natural, short-term pockets of warm water. The water is warmed naturally by environmental factors and weather patterns, and the water retains its warmth for short periods of time.

During the winter, manatees move toward the warmer waters of Florida. Typically, manatees seek warm water refuge near natural springs or power plants where clean, warm water is discharged into basins and warm nearby waterways. Cold waters are harmful to manatees because it causes stressors which increase risks to infections and other ailments like lesions, pneumonia and heart conditions, according to the study.  This is what attracts manatees to Fort Pierce waterways during the winter months from November through March. During the summer, manatees can travel as far north as Georgia and as far west as Alabama, the study noted.

“This study shows the value of citizen science and the decades of work that were needed to establish the ongoing usage of Moore's Creek by manatees,” said Dr. Beth Brady. “Manatees visit the creek as a source of freshwater as well for a short period of time when waters in the creek are slightly warmer than the waters in the Indian River Lagoon. Manatees rely on warm water sources such as powerplants during winter months. This study also shows what happens after a powerplant shuts down and the reasons why manatees still come to this habitat.”

The study is published by PLOS ONE, the first fully Open Access journal for researchers. Read “Persistent long-term habitat use by Florida Manatees at Fort Pierce, Florida from 1997 to 2020,” at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0297636