Coastal Restoration

A new study offers the most robust proof yet that a new species of manta ray is lurking in the Gulf of Mexico.

Scientists believed there was only one species of manta ray until 2009, when Andrea Marshall, then a graduate student at the University of Queensland in Australia, showed that there were actually two distinct species: the coastal-living reef manta ray and the open-ocean oceanic manta ray. Marshall suspected there was even a third irregularly colored manta species. But the rays were hard to glimpse and even harder to capture. The specter of this missing manta has lingered over manta biologists ever since.

Now, a new study offers the most robust genetic evidence yet of the new species, which scientists have dubbed the Caribbean manta ray. “It is nice to see that the majority of the manta research community is united behind the idea that there is indeed a third species of manta ray,” says Marshall, who was not involved with the research.

“The fact that we are still identifying new species of megafauna is amazing,” says Josh Stewart, an associate director of the nonprofit the Manta Trust and an author on the study. “These aren’t tiny gobies that can go around undetected.” It’s incredibly tricky to identify a Caribbean ray unless you know exactly what you’re looking for, as the species have highly variable appearances, says Stewart. Take the mouth, for example. Some Caribbean rays have white mouths, others have black mouths, and some have mouths that fall somewhere, vaguely, in between. “They always kind of look like a bizarre mix of things,” Stewart says.

Antarctic seabirds called skuas are so clever that they can recognize individual humans after seeing them only a few times. Some Korean researchers discovered this by messing with the birds’ nests and then waiting to get attacked. They’re either very brave or have never watched The Birds.

The study took place on Antarctica’s King George Island. The animals here didn’t evolve around humans. People have only been making appearances on the island since the 1950s or so. Today 10 countries have research stations on the island. Korea Polar Research Institute scientist Won Young Lee and his coauthors study brown skuas here, which are like big, dark-colored gulls.

In the winter of 2014–2015, researchers visited skua nests once a week to check on their eggs and chicks. They suspected that the birds could recognize them, and were unhappy about humans poking at their nests. If a skua wants you to go away, it will give not-so-subtle hints like attacking your head.

So the researchers set up an experiment. Starting in the fourth week of their study, two researchers visited each nest at a time. One of them, the “intruder,” had checked on the nest in previous weeks. The other, “neutral” researcher had never been to the nest before. As they approached the nest, the researchers recorded how close they could get before the birds attacked. Then they split up and walked in opposite directions, observing which person the birds chased after.

As the weeks went on, skuas attacked from greater distances. But they didn’t attack just anybody. All seven of the nesting pairs directed their attacks at the known intruder. The birds “reacted very aggressively” after five visits, the authors write, including kicking intruders in the head. They ignored the neutral humans.

Even though the researcher pairs wore identical clothing for their experiments, the skuas had no trouble spotting people who had fiddled with their nests in the past. The researchers don’t think the birds were using smell to tell them apart, since the site is windy. More likely, the birds relied on human facial features and body postures.

This is especially impressive since the birds evolved without ever seeing a human. There’s no reason they should have a natural ability to recognize us. Two other local bird species, sheathbills and Antarctic terns, don’t seem to discriminate between people.

The scientists chalk it up to “high cognitive abilities” on the part of brown skuas. In other words, they may just be especially smart. This makes sense; the birds are predators that have to be flexible to find their prey. Brown skuas have been seen chasing other large birds and taking their food. They’ll even steal drops of breast milk from nursing elephant seals. This is a bird you don’t want to cross—and after you do, you might want to wear a mask.

Scientists led by the USF College of Marine Science used NASA satellite observations to discover the largest bloom of macroalgae in the world called the Great Atlantic Sargassum Belt (GASB), as reported in Science.

They confirmed that the belt of brown macroalgae called Sargassum forms its shape in response to ocean currents, based on numerical simulations. It can grow so large that it blankets the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico. This happened last year when more than 20 million tons of it—heavier than 200 fully loaded aircraft carriers—floated in surface waters and some of which wreaked havoc on shorelines lining the tropical Atlantic, Caribbean Sea, Gulf of Mexico, and east coast of Florida.

The team also used environmental and field data to suggest that the belt forms seasonally in response to two key nutrient inputs: one human-derived, and one natural. In the spring and summer, Amazon River discharge adds nutrients to the ocean, and such discharged nutrients may have increased in recent years due to increased deforestation and fertilizer use. In the winter, upwelling off the West African coast delivers nutrients from deep waters to the ocean surface where the Sargassum grows.

"The evidence for nutrient enrichment is preliminary and based on limited field data and other environmental data, and we need more research to confirm this hypothesis," said Dr. Chuanmin Hu of the USF College of Marine Science, who led the study and has studied Sargassum using satellites since 2006. "On the other hand, based on the last 20 years of data, I can say that the belt is very likely to be a new normal," said Hu.