Water-Related News

SWFWMD Reports Gains in Seagrass Coverage in Charlotte Harbor

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Scientists with the Southwest Florida Water Management District’s Surface Water Improvement and Management (SWIM) Program released the results of the 2012 seagrass mapping study showing a 4.4 percent increase in seagrass coverage in Charlotte Harbor. The District maps seagrass in five estuaries spanning the five coastal counties of Pinellas, Hillsborough, Manatee, Sarasota, and Charlotte. Charlotte Harbor is Florida’s second largest open water estuary, and provides some of the most productive estuarine ecosystems in southwest Florida. This is the second consecutive survey to show increases for the system from 2008 values. The study also shows gains in Tampa Bay and Lemon Bay.

The results show Charlotte Harbor gained 804 acres of seagrass between 2010 and 2012. The area now collectively supports 18,991 acres of seagrass beds, the largest amount of seagrass measured since 1996. Seagrass acreage in Charlotte Harbor has remained around 18,000 acres since 2000, making 2012 estimates a significant gain towards the protection and recovery of seagrass in the system. Tampa Bay gained 5.3 percent gain while the smaller Lemon Bay system gained 67 acres, a 2.2 percent increase.

Documenting the extent of seagrass and how it changes overtime is a valuable tool for scientists throughout the state of Florida. Seagrasses are an important barometer of a bay’s health because they require relatively clean water to flourish, thus they are sensitive to changes in water clarity and quality. The District’s maps are used as a tool for measuring and tracking biological integrity of estuaries as it relates to water quality conditions. Seagrass generally grows in waters less than six feet deep, but in the clear waters around Boca Grande Pass it can be found in water 8 to 10 feet deep.

The District began its formal seagrass mapping program in 1988. As part of the program, SWIM scientists assess seagrass in five Gulf coast estuaries. Every two years maps are produced from aerial photographs and then verified for accuracy by conducting field surveys. The results are used to track trends in seagrass and to evaluate ongoing water quality improvement efforts.