The Tampa Bay Estuary has gained sea grass, but Northern Bay is still struggling

There is some good and bad news about the sea grass beds that spread out at Florida’s largest open water estuary.

Good news: For the first time in nearly a decade, Tampa Bay has seen an overall increase in aquatic plants, reducing erosion, reducing pollution, and is a general indicator of bay health. Since 2022, the Bay has added about 1,400 acres of sea grass, increasing its profits by around 5%.

Bad news: Old Tampa Bay, the northern section of the bay, has been in a record amount of sea grass since the pursuit began in 1988. That part of the bay has been blocked by poor circulation under three main bridges, losing more than 320 acres of sea grass over the past two years.

These highs and lows were first published Wednesday at a meeting with state and local scientists in downtown St. Petersburg, following the results of the latest biennial seagrass mapping of the water management district in southwestern Florida.

“The reason we map sea grass is because it gives the pulse of the estuary. And the pulse is better,” said Chris Anastasiu, the district’s leading water quality scientist and director of the Seagrass Mapping Program.

“I think we’re seeing a positive response, except in the old Tampa Bay,” he said in an interview. Bay experts say nutrient contamination combined with additional stress from warm, slow moving water is why old Tampa Bay continues to struggle.

According to Anastasiou, in addition to Old Tampa Bay, other parts of the bay have either increased sea grass beds or remained unchanged from the previous survey. Currently, there are over 31,500 acres of seagrass across the bay, increasing by 36% in the past 30 years, approaching the overall recovery target for the total acres. Lower Bay currently has a record amount of underwater plants over 8,000 acres.

Seagrass experts, who started work in December 2023, flew through the bay on a sunny winter day, took photos of the seabed and studied the results. The data is basically a snapshot of the Bay from this period last year. It doesn’t explain the relentless hits of Tropical Storm Debby and Hurricanes Helene and Milton.

In 2023, mapping results showed that Tampa Bay had lost more than 4,100 acres of sea grass in two years. It was the first time that the Water District had recorded a decline in three consecutive studies.

The consensus on why Tampa Bay was actively profiting this time was partly a long period of dry weather, where months of rain had been thrown into drought. While drought is good for water quality, uncontaminated spills are spreading to the bay, experts immediately reminded a group of scientists on Wednesday that drought is not a recovery strategy.

During the five months since the latest results were collected, ending in April 2024, there was also a Tamer Red Tide condition compared to previous studies. It may have contributed to healthier water. Furthermore, previous results accounted for Pannypoint wastewater disasters where millions of gallons of pollution were dumped into the bay.

Most of the overall profits at the estuary come from Hillsboro Bay, just south of downtown Tampa. According to the Tampa Bay Estuary Program, long, flat sea grass species known as shawl grass are known to have booms and busts, and an increase in shallow bays beyond Hillsboro Bay is a shallow grass bed.

In 2022, Hillsboro Bay had about 400 acres of sea grass. It is now over 1,100 acres. This is an increase of 185%.

“It’s easy to fasten negatively, especially when it comes to the environment. But Tampa Bay remains an incredible story of success,” says Mayaburk, assistant director of the Tampa Bay Estuary Program. “Our story may not be simple. This year’s results show both record-breaking seagrass coverage in Lower Tampa Bay and record lows in Old Tampa Bay, but we know how to work together for a better Tampa Bay.”

Water management in southwestern Florida is more than just tracking the sea grass range in Tampa Bay. On Wednesday, the results of recent surveys from St. Joseph’s Sound, Sarasota Bay, Lemon Bay and Charlotte Harbor were also released.

Perhaps the biggest success story of this research cycle was in Sarasota Bay. The waterway has acquired about 2,000 acres of sea grass over two years, or an overall increase of 19%. Meanwhile, Charlotte Harbor lost nearly 900 acres.

Scientists will visit the sky in December and begin their next two years of sea grass research.