Crystal River, Credit: Paul Nicklen/National Geographic 2013.I
Slide from “Manatee UME on the Florida Atlantic Coast 2020-2021” -Martine de Wit, DVM
I wanted to share today’post because I have recently been exposed to this inofrmation. Most of it is very disturbing, and unfortunately, it is going to get even more so. We have to prepare. We have to decide. As winter approaches, we are going to have to face some hard choices about manatees.
As we all know, Florida’s manatee’s are in the middle of a UME or Unusual Mortality Event. It has been documented by FWC that most deaths are due to starvation as the seagrass meadows of the 156 mile long Indian River Lagoon are dead, dying, or in poor condition, due to poor water quality, algae blooms, discharges (S.IRL) , and thus lack of sunlight. The Florida Wildlife Commission’s 2021 numbers are displayed in the chart below and more information can be found here.
This August, Martine de Wit, DVM, presented a power point to the Management Board of the Indian River Lagoon Council. It is heartbreaking but should be seen by all.
The bottom line is: this winter the migrating manatees will have site fidelity (like elephants) to the four power plants along the IRL. In the past, as many as 2500 have stayed true to the warm waters near Cape Canaveral’s power plant in the northern central IRL. The question is, not who will come this year, it’s just how many. These manatees will be warm but there are no longer historic seagrass beds to eat. In spite of this, they will stay and put being warm first. Since we know there is no seagrass and since we know they will gather in their known warm waters, should we try to feed them or relocate them/something not supported in the past…
Dr Widder is a world-renowned bioluminescence expert; she has even worked with the US Navy in the “design” of ships that would not cause bioluminescent disruption in the oceans, and thus give away their location to enemy ships.
This was my question to Dr Widder:
Dear Edie, My parents rented kayaks to go see the bioluminescence in the IRL. It got me thinking. Is the light caused by the same creatures that cause toxic algae blooms in the lagoon? Is the bioluminescence a bad sign for the health of the lagoon? Thank you. Hope all is well.
Hi Jacqui – It’s kind of a good news bad news story. The dinoflagellate producing the light show, Pyrodinium bahamense, happens to be one that produces saxitoxin. Interestingly it’s the same dino that’s responsible for the bioluminescent bays in Puerto Rico and in those bays it doesn’t produce the saxitoxin. Here it does. It’s not known why although I have a theory and it has nothing to do with pollution. (It’s a long story having to do with how their bioluminescence functions to protect them from predators under different concentrations.)
Dino blooms are usually preceded by rain events that flush nutrients into the water and then a series of calm sunny days that promote photosynthesis. Blooms like the one we’re seeing now used to be routine according to some of the older fishermen I’ve talked to. They called it fire in the water. The fact is the water can’t be too polluted or the dinoflagellates won’t grow. I’ll send you an article with some pictures I took.
Here is a photo Dr Widder took of bioluminescence in the lagoon I copied and a link to a remarkable video.
In conclusion, I looked up saxitoxin and learned it is a “paralytic shellfish toxin” that is found is some shellfish and especially puffer fish. It has been found in few other places in the US as well as in the Indian River Lagoon. I guess the little dinoflagellates, the same ones that make the pretty bioluminescence light, not always, but sometimes, will produce this toxin which gets spread to some shellfish and some fish. If such a shellfish or fish is ingested, it will make a human very sick. Around 2002, 28 people got so sick here, in the Merritt Island area, and in a few other areas of the county, that now there is a permanent government ban on harvesting/eating IRL puffer fish in the entire IRL.
Since I am nowhere close to a scientist, I will just share some links below and refrain from speculating what is “good or bad. ” Nonetheless, I think I can safely say that sometimes beauty and danger walk hand in hand in this magical world of our Indian River Lagoon.