What’s Killing Florida’s Manatees This Time?

What’s behind the mysterious deaths of more than a hundred of Florida’s manatees?

An endangered Florida manatee. Photo: Keith Ramos / USFWS

In the past year an unknown scourge has been killing the manatees that live in Florida’s Indian River Lagoon. Some 111 manatees have experienced unusual deaths in the region, says Nadia Drake for Wired:

Other than being dead, the manatees look remarkably normal. Whatever is killing them strikes quickly and without much warning. Biologists haven’t been able to find any suffering manatees – just dead ones – and are missing crucial behavioral observations.

In the past week the news came outand was distributed widely—that the deaths were down to a “suite of toxins,” some that may be previously unknown. The toxins were found on the manatee’s food and are thought to be produced by algae. (Scientists don’t yet know which one, or ones.) The toxin kills mammal cells, and most stories on the toxins made this seem like a pretty cut and dry case. But, as Drake writes in a new story for Wired, it’s probably not so simple:

Before the toxins can be linked to the deaths, there are many crucial questions that need answers — including whether the compounds are found in the carcasses.

…It’s easy to see why these results could be misinterpreted as identifying the culprit behind the manatee die-off: Finding lethal compounds associated with the seaweed that manatees are eating seems like a pretty solid connection. But it’s only circumstantial. Despite what you may have read elsewhere, Moeller’s work is simply another clue about what might be going on in the lagoon.

To help firm up the result, Drake says, “the toxin responsible for the animals’ deaths needs to be found in the animals themselves, in the tissues or organs that have been compromised. So far that has not happened.”

This has been a rough year for Florida’s manatees all around. On top of the mystery murder, an unrelated bloom of toxic red algae caused one of the biggest annual manatee die offs on record. This is all on top of the usual stresses this endangered species deals with—habitat loss, polluted water and the occasional wayward boat propeller.

More from Smithsonian.com:

Dear Florida: Stop Messing With Mating Manatees
Touch a Manatee, Spend Six Months in Jail 

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