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Mangroves moving into North Florida

5:46 PM, Dec 31, 2013   |    comments
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ST. AUGUSTINE, Fla. -- While giving tours around St. Augustine via boat and kayak, Zach McKenna started noticing something new to the area: mangroves. Specifically, red mangroves.

"We're starting to see red mangroves pop up," said McKenna, who ownsSt. Augustine Eco Tours. "When you're with other scientists and educators, they'll say, 'Hey, you won't believe this. We're tracking red mangroves and they're not supposed to be here."

About seven years ago, he started spotting them around St. Augustine. He had seen the more common black mangroves before, but the red mangrove -- with its big roots -- really stuck out. It's typically found in the southern part of Florida.

"It's been a slow and steady increase," McKenna said.

Scientists reported this week in the journal Proceedings of the National Academy of Sciences that mangroves are marching further north along Florida's Atlantic coast over the last 30 years, creeping into areas just south of St. Augustine.

And why?

"The proposed theory now is it's due to a lack of hard freezes. It doesn't mean there are not hard freezes here," but that the number of hard freezes per year is less, Dr. Gary Raulerson explained.  He is a mangrove ecologist and works at the Guana Tolomato Mantanzas National Estuarine Research Reserve.

Raulerson said research also shows mangroves' trunks get stronger over time.

"The mangroves have an opportunity to grow large enough so they're protecting themselves," he added.

Raulerson said while black mangroves are more common in St. Johns County, three varieties (the black, red and white) are starting to pop up this far north.  

It may be too early to know the full impact on the wildlife. But the first noticeable change could be in the surrounding plants.

"It will be going form salt marshes to mangroves. Shrubbery mangroves that are six to eight feet tall black mangroves," Raulerson said.

Raulerson said it could be "a long time" before animals may feel the impact.

He wondered aloud, "Do the crabs change? Do the fisheries change? Does the water quality change?"

Some scientists say the increase of mangroves can be a good thing because they are ecosystems that need protection.  However, mangroves could also negatively impact salt marshes, which are also important ecosystems.

"These changes in climate and the introduction of a species that aren't historically here will definitely change the flora which could then change the fauna of the area," McKenna noted.

Certainly, the mangrove is an additional item that McKenna points to in his tours around the natural side of St. Augustine.

----To connect with Jessica Clark, follow her on Twitter at @JessicaFCN or Like her on Facebook.

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