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Warmer water temperatures already have effect on Sarasota Bay

Local experts and water recreation guides weigh in on the impacts of rising water temperatures in Sarasota Bay.

Warmer water temperatures in Florida may have future impacts on Sarasota Bay, according to some local experts.
Warmer water temperatures in Florida may have future impacts on Sarasota Bay, according to some local experts.
Photo by Carter Weinhofer
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“It’s not your imagination, it is getting warmer,” said Dave Tomasko, the executive director of the Sarasota Bay Estuary Program.

A recent study done by the Sarasota Bay Estuary Program looked at water temperatures between 1970 and 2022. The data showed that there hasn’t been a single month in which water temperatures have decreased compared to that same month in the previous year in Sarasota Bay. 

He also said researchers have known the Gulf of Mexico to be getting warmer over the last couple of decades. 

Locally, Tomasko pointed to data that proves air temperatures are slowly increasing over the years. Tomasko said that this area used to see air temperatures of 60 degrees in the mornings of August, but in the last 20 years there hasn’t been a single August hour below 70 degrees. 

"We’re not getting as cold in the wintertime," Tomasko said. "We’re not getting as cold in the summertime."

This data echoes recently recorded data in South Florida. The month of July was historic for water temperatures in Florida. A buoy located south of Miami in Manatee Bay recorded a temperature of 101.1 degrees Fahrenheit. 

“It does seem pretty safe to say that, in parts of Florida, we have temperatures as hot as a hot tub,” Tomasko said. 

Recently, Tomasko was on a trip to the Florida Keys to work on a side project and said the water wasn’t more refreshing to be in. 

This impacts local industries, like fishing charters and kayak excursions, Tomasko said. If the water isn’t enjoyable, these industries could have a hard time getting people out on the water. 

Aside from the enjoyment factor, warmer water levels are troubling for a number of other reasons. Warmer water doesn’t hold as much oxygen, which impacts the growth of fish and other organisms, Tomasko said.

Tomasko also explained that thermal expansion is a prominent cause of sea level rise, and that the melting of the ice caps isn’t the highest contributor like some may think.

“It’s not a separate issue of sea level rise and warmer temperatures,” Tomasko said. “They’re co-occurring because they’re related.” 

Simply put, water molecules tend to change volume in response to temperature changes, so warmer water causes the molecules to expand and take up more space. With higher water levels comes an increase in roadway flooding.

“We’re going to have warmer, higher water on a regular basis,” Tomasko said. 

Warmer temperatures also help speed up rates of algae growth, notably a species called lyngbya. It’s commonly seen in the bay, Tomasko said. It looks sort of like brown and green clumps of mushy hair. When it comes to the surface, it smells unpleasant. 

This is not the same algae that causes red tide. Lyngbya algae has been around for centuries, but Tomasko said research has shown algal growth is exacerbated by an increase in temperature and an increase in nutrients. 

That said, Tomasko added that warming temperatures are out of the common person’s control. 

“There’s not much we can do to stop global warming and the warming of the waters,” Tomasko said. “But what that does mean is we’re going to have to do more on nutrient management, which we can control.” 

Local views

This summer Orion Morton has been feeling the effects of warmer temperatures, both on land and in the water, he said. 

He is a kayak guide in South Lido and runs a small agriculture business while serving on the board of Suncoast Waterkeeper.

Morton grew up in Florida, mostly on the East Coast, before moving to the Sarasota Bay area. Every summer, he would complain with friends that that summer was the hottest yet. 

“This summer, everyone’s like, ‘All kidding aside, I think it does actually feel hotter,’” Morton said. 

It’s getting hotter and drier earlier in the season, he said.

On kayak tours, Morton said customers are usually encouraged to go at different times of day, usually earlier is better. If it’s not heat that’s the problem, it’ll be thunderstorms, he said. 

Fortunately, Morton hasn’t seen any heat exhaustion cases yet. But he did say kayaking companies are remaining diligent, making sure people are staying hydrated. On the water, there’s a breeze and some shade when the tours go through mangrove tunnels. But when kayaks are loaded and unloaded in direct sun, that’s when Morton said workers are really looking out for each other. 

The warmer waters also impact fisheries in terms of what fishermen are catching and where. 

Rusty Chinnis serves on the Suncoast Waterkeeper board along with Morton, and has been living in the area since 1981. Chinnis has been exploring Florida’s waters for 40 years as a fishing guide. 

“It was really this year when I started becoming aware of the water temperatures,” Chinnis said. 

Recently, Chinnis was fishing in the area with some friends and they started getting hits of yellowtail snapper. There was a time, he said, when yellowtail snapper wasn’t caught off the beaches here. 

Additionally, Chinnis witnessed the snook fishery take off in Homosassa, further north up the coast. There always used to be some snook there, but that species is very temperature-dependent, Chinnis said. Temperatures around 40 or 50 degrees would be deadly. 

In years past, the species were seen there because they could retreat to the warmer springs. But now, with warmer water and air temperatures, the fish can flourish in more than just the springs areas. 

Overall, he's seen a trend of species shifting further north as temperatures get warmer. 

“It’s a ‘for sure’ thing,” Chinnis said. “It’s not like a ‘maybe’ or a ‘what if.’”

Chinnis agreed with Tomasko, saying that heat also exacerbates algal growth, something he’s seen as a prominent issue to the bay in recent years. Warmer waters combine with an increase in nutrients to create perfect conditions for algal growth. 

“That’s just insult to injury,” Chinnis said. “It’s not a good situation.” 

While local efforts may not be able to change the course of rising temperatures, Chinnis said there’s a lot that can be done to mitigate nutrients in the bay. 

At the smallest scale, it’s as simple as picking up after your dog, Chinnis said. Fertilizer bans also go into effect during certain months of the year to try to limit nutrient runoff. 

He also mentioned it’s important to vote in elected officials that will care about the issues. 

As a former building contractor, Chinnis said he tries to discourage people from the common narrative of “developers versus environmentalists.” But he did say that more people moving to Florida has worsened issues of stormwater runoff and failing infrastructure, and created a greater need for upgraded sewer systems.  

“People come down here because of the water quality, the sea life, the fish, the birds,” Chinnis said. “If we don’t take care of it, we’ll lose it.”



Carter Weinhofer

Carter Weinhofer is the Longboat Key news reporter for the Observer. Originally from a small town in Pennsylvania, he moved to St. Petersburg to attend Eckerd College until graduating in 2023. During his entire undergraduate career, he worked at the student newspaper, The Current, holding positions from science reporter to editor-in-chief.

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