Sarasota Bay found to have its largest seagrass acreage since the 1950s

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Southwest Florida Water Management District releases findings of its research from 2012 to 2014

The more seagrass, the healthier a bay, scientists say. Image from Wikimedia
The more seagrass, the healthier a bay, scientists say. Image from Wikimedia

Seagrass acreage in Sarasota Bay is at its highest level since the 1950s, having grown by 701 acres from 2012 to 2014, the Southwest Florida Water Management District (SWFWMD) has announced.

Scientists with SWFWMD’s Surface Water Improvement and Management, or SWIM program, released the results of the 2014 seagrass mapping study last week. They show Sarasota Bay supports 13,288 acres of seagrass beds, a news release says.

Sarasota Bay includes five segments of Manatee and Sarasota county waters, the release explains. All of them gained seagrass from 2012 to 2014, with an overall increase of 5.6 percent since 2012, the release notes.

Sarasota Bay contained more seagrass as of 2014 than at any other time in the history of the SWFWMD mapping program, the release says; this is the largest amount of seagrass measured since the 1950s.

In Dec. 16 email to area local government leaders, Mark Anderson, executive director of the Sarasota Bay Estuary Program, wrote, “There has been a steady increase in both patchy and continuous beds since 1988 with continuous beds (>75% coverage) gaining a larger proportionate share of those mapped. These trends appear to correlate nicely with declining trends in chlorophyll a (a measure of algae in the water column) bay-wide.”

A graph shows details about seagrass coverage in Sarasota Bay. Image courtesy Southwest Florida Water Management District
A graph shows details about seagrass coverage in Sarasota Bay. Image courtesy Southwest Florida Water Management District
A chart shows changes in specific areas. Image courtesy Southwest Florida Water Management District
A chart shows changes in specific areas. Image courtesy Southwest Florida Water Management District
This chart shows increases, in pink, in Sarasota Bay. Image courtesy Southwest Florida Water Management District
This chart shows notable increases, in pink, in Sarasota Bay. Image courtesy Southwest Florida Water Management District

SWFWMD maps seagrass in five estuaries spanning the five coastal counties of Sarasota, Pinellas, Hillsborough, Manatee and Charlotte, the news release adds.

Documenting the extent of seagrass and how it changes over time “is a valuable tool for scientists throughout Florida,” the release explains. “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 release says.

Seagrass generally grows in waters less than 6 feet deep, but in the clear waters around Egmont and Anclote keys, it can be found at a depth of 10 feet or greater, the release notes.

SWFWMD began its formal seagrass mapping program in 1988, the release adds. Every two years, maps are produced from aerial photographs and then verified for accuracy through field surveys, the release says.