![]() ![]() ( Read how Florida's beloved manatees are dying in alarming numbers again).įirst, they tested the equipment at CREA, a rehabilitation facility for sick or injured manatees in Iquitos, Perú. National Geographic Explorer Daniel Gonzalez-Socoloske, of Andrews University, in Michigan, saw how multibeam sonar had helped researchers monitor seal behavior around tidal power turbines in Scotland, so he teamed up with Gulley and Marmontel to find out if it could reveal the hidden world of Amazonian manatees. The result: detailed images that offer unprecedented ability to study manatees in dark waters. Navy in the 1960s to create scans of the seafloor and detect objects in the water column, multibeam sonar works by sending out multiple sonar beams in a fan-shaped pattern and measuring the time it takes for sound waves to reflect off the seabed or other objects back to a receiver. The researchers needed to learn the sonar signatures of manatees before using the equipment to identify and observe the herbivores in Amazonian rivers. Right: A multibeam sonar array records manatees in a holding tank at CREA. “Everyone asks about it, and we just don’t know.” “The question about abundance has been on our minds forever,” she says. Because no one knows how many manatees live in the sprawling Amazon Basin, one hoped-for outcome is a population estimate-crucial for developing strategies to protect the animals, Marmontel says. She’s part of a small team of researchers funded by the National Geographic Society who are pioneering use of imaging technology called multibeam sonar to document the lives of Amazonian manatees. “You just never see them.” Throughout a career spanning several decades, Marmontel says she’s averaged just one glimpse a year. “While other creatures like otters and river dolphins are more visible, manatees are different,” she says. “Studying them is very challenging-you have to build up from little scratches, working on signs, vestiges, remains, bones,” says Miriam Marmontel, a member of the National Geographic team and a leading expert on Amazonian manatees at Mamirauá Sustainable Development Institute, in Tefé, Brazil. The murky, tannic waters explain why researchers rarely if ever see the animals. Now, for the first time, a research team using sonar technology has “seen” these elusive animals in the wild, in a protected area in Brazil.Īmazonian manatees-the smallest, at eight to nine feet long and weighing between 650 and a thousand pounds-are the only ones that live entirely in fresh water, in rivers darkened by sediment washed down from the Andes and stained reddish-brown by decomposing forest vegetation. “Amazonian manatees, by contrast, are nearly impossible to see, much less to photograph. “What we know about Florida manatees is thanks to the fact that they congregate in water that is clear enough for us to see them,” says Gulley, who’s a National Geographic Explorer. ![]()
0 Comments
Leave a Reply. |