Manatees are experts at playing hide and seek. They spend most of their lives underwater, surfacing every five minutes or so to take a breath and then sinking back below the surface.
That has always made it hard for biologists to spot them, especially while doing the annual aerial survey to determine how many are swimming through Florida’s waterways.
But now scientists at the U.S. Geological Survey have developed the first laboratory test for detecting manatee DNA in water samples, so they can say with certainty where manatees live.
And where do those traces of manatee DNA come from? "Mostly poop," lead scientist Margaret E. Hunter of the U.S. Geological Survey in Gainesville said Monday.
She said the DNA test can bolster the accuracy of the annual aerial surveys, which have always produced numbers that were less than reliable. One manatee biologist famously compared the aerial counts to "trying to count popcorn as it pops."
"It’s a really great tool," Hunter said.
Working for five years, Hunter’s team isolated a unique DNA segment that’s found in manatees’ body residues — not just poop, but also saliva, skin cells and even exhaled water vapor. They developed a genetic marker that gives off fluorescent light in the presence of manatee DNA. They described their discovery in a scientific paper published last week in the journal Endangered Species Research.
By using the DNA test, scientists can not only identify the habitats that manatees use, they can also better monitor the patterns of their seasonal movements as the water cools down and warms up.
They tried out their test in areas of the Florida Panhandle, where the manatee population has been growing, as well as the waterways of Brevard County, which has one of the largest manatee populations on the state’s East Coast, Hunter said. They also tried it at locations in Cuba and Cameroon where relatives of the Florida manatee are known to show up.
While the test will show if manatees have been present any time in the past month, it can’t pick out individual manatees or even identify how many manatees might have been swimming through the area, Hunter said. That’s why it cannot yet replace the aerial surveys for counting the manatees as they pop to the surface.
The most recent aerial survey, conducted in January, found more than 6,000 manatees huddled together for warmth in the state’s springs and power plant outfalls.
Fossils show manatees have existed in Florida for centuries. The first written account of someone seeing a manatee comes from the log of Christopher Columbus, who noted that mermaids were not as attractive as he had been led to believe.
Ever since Jacques Cousteau featured them in a 1972 television documentary called Forgotten Mermaids, they have become an extremely popular symbol of the state. The manatee’s homely image is depicted on everything from license plates (which pay for state manatee research) to barbecue sauce labels and liquor bottle holders.