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Hurricane Ian could lead to increase in algae blooms

Posted at 9:13 PM, Oct 09, 2022
and last updated 2022-10-09 21:13:37-04

CAPE CORAL, Fla — While it might be sometime before we can fully enjoy being near the Gulf waters again, the short- and long-term health of our local waterways is still in question after Hurricane Ian’s surge and rainfall flushed hundreds of tons of silt, pollution, and organic matter into the Gulf of Mexico.

Dr. Eric Milbrandt, the Marine Laboratory Director with the Sanibel Captiva Conservation Foundation says the last size of areas impacted by Hurricane Ian adds additional variables into that health.

“We don’t even really know,” said Dr. Milbrandt. “There has been a few examples, the Indonesian Tsunami, the tsunami in Japan, for example, these are widespread events effecting people and coastlines. The subsequent impact path cascade of things that can happen can be varied.”

In the short term, Dr. Milbrant says the concern is the increase in organ material released into the estuary.

“The leaves that blew off the mangroves and all the other trees, are all in the water decomposing, producing a lot of oxygen demand by bacteria,” said Dr. Milbrandt. “And so, one thing we are sort of seeing is at least initially low oxygen levels. What we do not want to see is areas with no oxygen.”

That lack of oxygen can cause fish kills, something we saw earlier this summer from decaying algae blooms. And speaking of algae blooms, Dr. Milbrandt says the increase in nutrients in the water, could lead to more algae blooms including red tide. While the sample size is small, the year after charley and irma, southwest florida saw major red tidial blooms.

“We had large, long lasting red tide blooms, which are algae that bloom and cause respiratory irritation,” said Dr. Milbrandt. “So, that is not a formula, that sample size is relatively small, over a 20-year period, and it is very difficult to predict such a large disturbance happens, what is going to happen. But certainly, the conditions would be favorable for some kind of bloom development.”

And not only can algae blooms affect the water quality, but Dr. Milbrandt says the pollution added to the estuaries, will likely impact the smallest parts of the food chain, like shrimp, oysters, and clams.

“All the things dependent on our mangrove ecosystems and the dropping leaves and the decomposition that happens, those contaminates are mobilized now,” said Dr. Milbrandt. “So, there is going to be some of the distributed throughout the food web.”

Despite the negative impacts, Dr. Milbrandt says our local ecosystems will adapt to its new normal.

“We think that the barrier islands will adapt and adjust, and the ecology will adapt and adjust to these new areas and new underwater areas,” said Dr. Milbrandt. “Although it will take time.”

Dr. Milbrandt says the Sanibel Captiva Conservation Foundation is still assessing how their scientific equipment is doing after Hurricane Ian, but with plenty of data ahead of the storm, they have strong sample size to do research against.