birostris with regional color variations.Īt this stage there is "tempting evidence" for each of these hypotheses, she said. Why? another mystery to uncover.”Īfter diving with Gulf mantas recently, Marshall, who first indentified the two known manta species, said she thinks that they may represent a third species but might also be hybrids or even M. “What I’ve seen from tags is that they seem to be spending a fair amount of time in the southern Gulf aggregation area but occasionally move over 56 miles before returning to the aggregation site. "Interestingly, at Flower Garden Banks, tend to be really small, while in the southern Gulf, the ones I recently tagged are really big, birostris-sized animals. "It's almost like they are a hybrid," Graham said. Also, the Gulf mantas' travel habits lie somewhere between the two extremes. She said Gulf mantas share physical and behavioral elements of both confirmed species, including varied sizes, mixed markings, and colors. The Wildlife Conservation Society's Graham has studied Gulf mantas closely and conducted acoustic tagging research at Flower Garden. Scientists in the Gulf have been studying the region's mantas-informally called Yucatán mantas-to see where these stingray cousins fit on the family tree. The larger species, Manta birostris can top 4,400 pounds (2,000 kilograms) and tends to wander widely on deep-ocean migrations through a variety of marine habitats. In 2008 the megafauna foundation's Marshall discovered that the manta ray is actually two separate species, and her work left the door open for the existence of a third species.Īccording to Marshall's work, the smaller, more familiar manta species, Manta alfredi, tends to stay near coasts as a year-round coral reef resident with a small home range. "So while those at the Flower Gardens may not be directly impacted, they may also move into areas affected by the spill," said Tim Clark, a marine ecologist with the National Park of American Samoa. In addition, scientists believe that mantas are likely found throughout the Gulf. (See related pictures: "Giant Rays' 'Feeding Frenzy' Spots Protected.") "So it's very difficult to estimate the impact of something like this." However, "we have this huge threat of a deepwater oil spill, but don't know any population sizes, and we have no baseline," she added. (Related picture: " First Giant Manta Ray Born in Captivity Dies.")Ĭomplicating matters is the Gulf's role as a manta hot spot.įortunately, well-known Gulf manta haunts such as Flower Garden Banks National Marine Sanctuary were not in the direct path of the oil, said the Wildlife Conservation Society's Graham. "So how can we predict with accuracy what will happen?" "The main problem is that we know about their biology," Alvarez said. Oil could also disrupt mantas' migrations throughout the Gulf, or even their reproduction-no one knows where the animals give birth, according to Mexican marine biologist Silvia Hinojosa Alvarez of the Mexican Caribbean Manta Project. "It won't clear up over a few months."įor instance, oil-and dispersants used to break it up-might hurt the rays' plankton food sources, as well as the "cleaning stations" where mantas go to have their parasites eaten by smaller fish. The oil could affect the "ways mantas live their day-to-day lives for years," said marine biologist Andrea Marshall of the Mozambique-based Foundation for the Protection of Marine Megafauna. Each barrel equals 42 gallons, or 159 liters, of oil. What's more, there's so little known about Gulf mantas that scientists aren't sure if the 20-foot-wide (6-meter-wide) fish belong to one of two known manta species-or if the Gulf mantas are their own species altogether.Īfter burning and sinking last April, the damaged Deepwater Horizon wellhead released nearly five million barrels of oil into the northern Gulf of Mexico (map). "If they are covered, they will likely die." "Gill filaments, which enable mantas to extract oxygen from the water, are very vulnerable to any kind of toxin or oil coverage," Graham said. Mantas are filter feeders that reach huge sizes in part by taking in seawater and ejecting it through their gills, retaining plankton or other tiny creatures, according to Rachel Graham, lead shark scientist with the Wildlife Conservation Society's Ocean Giants Program. (Related: " Whale Sharks Killed, Displaced by Gulf Oil?") But it's the oil's unseen impacts, deep underwater, may be even more troubling, especially as preliminary studies suggest the spill isn't going away. In the weeks after the April 20 disaster, aerial photos and reports from boaters placed at least some mantas in the thick of the surface spill. The Gulf of Mexico's mysterious manta rays could face invisible and long-lasting threats from the BP oil spill, experts say. Deciphering the unseen, underwater effects of the Gulf oil spill.
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