Science and the Sea podcast

Until 2011, no one knew that a couple of groups of dolphins found along the coast of southeastern Australia were a separate species from all other dolphins. Burrunan dolphins are related to the two other known species of bottlenose dolphins. There are two groups of Burrunans—about 250 dolphins in all. But today, no one knows how much longer the species might be around. It’s critically endangered. And it’s threatened by several hazards, including industrial chemicals. In fact, the species contains higher levels of one group of chemicals than any other dolphins in the world. In a recent study, biologists tested 38 dolphins, of several species, that were found on the shore. In particular, they looked for a group of chemicals known as PFAS. They’re used in food packaging, firefighting foam, and non-stick cookware. They’re known as “forever” chemicals because they never break down. They wash into the sea from industrial and wastewater treatment plants, and runoff from the ground. The scientists found high levels of PFAS in all the dolphins. But by far the highest levels were in the Burrunans—10 times the concentration thought to cause liver problems and other health issues. And one dolphin had the highest level of the chemicals ever measured in any dolphin anywhere in the world. The Burrunans eat fish, which have high concentrations of the compounds in their livers—increasing the danger for a rare and endangered species of dolphin.

“Million Mounds” may be overstating the case a bit, but there’s no doubt it’s one of the most extensive deep-water coral reefs on the planet. Or make that part of one. Scientists recently discovered that the system extends far beyond Million Mounds—the biggest deep-water coral reef yet seen. The entire complex stretches along the southeastern Atlantic coast of the United States. It’s a few dozen miles out, from Miami to near Charleston. It encompasses about 50,000 square miles, at depths of about 2,000 feet or greater. Million Mounds had been the only part of the system that had been studied in detail. Most of the corals are on the many mounds and ridges found across the region—hence the name “Million Mounds.” Scientists used ships on the surface, plus robotic submersibles, to map a much larger region. The surface vessels scanned the ocean floor with sonar. And the submersibles provided close-up looks at selected locations. The corals aren’t like the vibrantly colored ones found in shallower seas. Instead, they’re all white. That’s because they’re mainly the “stony” part of a coral. They don’t contain the same microorganisms that provide the color for their shallower cousins. Those organisms need sunlight, and it’s too dark for them in the deep ocean. The deep-water coral filter food from the water—bits of organic matter that drift to the bottom. That allows them to survive—a lot of them—in the deep waters off the American coast.

For a tiny marine worm found in the Bay of Naples and elsewhere, life ends in a frenzy. The worms lose a lot of their internal organs, their eyes get bigger, and they rise to the surface. There, as they paddle furiously, they release sperm and eggs, creating the next generation. And it’s all triggered by moonlight. The worms are one of more than 10,000 species of marine bristle worm. They’re only about an inch long. Each body segment has a pair of paddle-like structures tipped with bristles. The worms live at the bottom of warm, shallow waters around the world. And they’re considered “living fossils”—they haven’t changed much in tens of millions of years. The bristle worms are especially sensitive to changing light levels. They build tubes on the ocean floor. When a shadow passes across them, they pull back into the tubes to elude possible predators. And their end-of-life ballet is triggered by moonlight. The body changes begin around the time of “new” Moon, when there’s little or no moonlight. The worms then rise to the surface not long after the full Moon. Scientists recently studied how that happens. They found that some proteins react differently with different light levels. Under bright sunlight, they stay apart, in separate units. But under dimmer conditions, the units stick together. That allows the worms to not only distinguish between day and night, but between different phases of the Moon—a light-activated “trigger” for a big change.

Conditions in the Arctic Ocean may be about to switch gears. That could mean that Arctic waters would become more like those in the North Atlantic—a process known as “atlantification.” As a result, sea ice would disappear a lot faster than it has in recent years. The rate of sea-ice loss peaked in 2007. The total amount of ice is still going down, but much more slowly than it was before. In December of 2023, in fact, the sea ice increased at a higher rate than in all but two other months in the past 45 years. A recent study said the slowdown in ice loss may be a result of the Arctic dipole—a pattern in the way air circulates over the far north. Today, there’s high pressure over the Canadian arctic, and low pressure over Siberia. That pattern reduces the flow of warmer water from the North Atlantic Ocean into the Arctic Ocean. There’s a thicker layer of colder, fresher water at the top of the Arctic. That keeps the ice from vanishing as fast as expected based on the higher air temperatures produced by our warming climate. Scientists looked at decades of observations made from ships, airplanes, and satellites. They found that the dipole might be about to flip over—from “positive” to “negative.” If that happens, the changing circulation in the atmosphere would allow more water to flow in from the Atlantic. That would warm the upper layers of the Arctic, causing sea ice to disappear much faster—boosting the “atlantification” of the Arctic.

Some tiny sea snails may look like angels, but they act more like little devils. They rip their favorite prey from their shells. And the prey just happens to be a relative. Sea angels are found around the world, from the arctic to the tropical waters near the equator. Most range from the surface to depths of a couple of thousand feet, although some have been seen more than a mile down. Sea angels are born with shells, but they lose them as they become adults. They’re no more than a couple of inches long, and they have streamlined bodies. They’re mostly transparent, which helps them hide from predators. The Antarctic sea angel has extra protection: it produces a nasty chemical that keeps most predators away. What gives sea angels their “angelic” appearance is a pair of wings. They’re adapted from the muscular foot of their land-based cousins. The creatures move through the water by flapping those wings. They can move twice as fast as their prey. Their favorite treat is another sea snail—the sea butterfly. Some angels lie in wait, while others are more active hunters. They grab their prey with small tentacles that extend from the head. Hooks allow them to pull the butterfly from its shell in as little as two minutes. Sea angels and their prey are jeopardized by climate change, which makes the oceans more acidic—a hazard for any creature that produces a shell. That’s an extra challenge for these angelic little devils flapping through the world’s oceans.

Now playing in the southwestern Pacific Ocean: Sharkcano—an underwater volcano filled with sharks. Officially, the volcano is Kavachi. It’s named for a fire god of a nearby culture. Its base is about three-quarters of a mile deep. Kavachi is one of the most active volcanoes on the planet—there’s almost always a little something going on. Its first recorded eruption came in 1939. Since then, it’s erupted at least eight more times, including a long-lasting one from late 2022 into ’23. The eruptions produce big underwater plumes of gas, rock, and ash. Currents carry the plumes miles away, staining the ocean surface. Some eruptions send debris into the sky. They can even build islands up to about half a mile long. The islands don’t last long, though—wind and waves quickly wear them down. An expedition in 2015 arrived during one of Kavachi’s rare quiet times. That allowed scientists to float above the volcano’s summit, where they could sample the water and rocks, map the crater’s contours, and look for life. And they found a lot of it. Big patches of microscopic organisms that feed on sulfur and carbon dioxide coated the volcano’s flanks. And snapper and other fish swam through the crater. That included silky sharks and scalloped hammerhead sharks—inspiring Kavachi’s nickname. The sharks probably swim in and out over the crater’s rim. But they seemed to be doing well in the Kavachi’s hot, murky, acidic waters—living inside the Sharkcano.

Chinstrap penguins may be contenders for the title of “world’s greatest power nappers.” A recent study found that penguins that are watching over their eggs or chicks nod off more than 10,000 times a day—for an average of just four seconds per nap. Chinstrap penguins live in Antarctica and nearby islands. Adults stand about two and a half feet tall, and weigh up to 10 or 12 pounds. They get their name from a thin line of black feathers that look like a chinstrap. They return to their nesting grounds every October or November—hundreds of thousands or more in a single colony. Males and females take turns watching over the nests while the other spend days fishing. Other chinstraps may try to steal the pebbles from their nests. And birds known as brown skuas try to grab the eggs or chicks. So nest-sitting is a full-time chore. Researchers studied 14 adults on King George Island, off the coast of Antarctica. They used sensors to record the penguins’ brain activity. They also logged location, motion, and other data. The instruments revealed that nesting parents frequently nodded off, then quickly popped back awake. The brain monitors showed that the parents were catching frequent naps—sometimes with only one side of the brain, sometimes the whole thing. The naps added up to 11 hours a day. That behavior wouldn’t be healthy for most animals. But it didn’t seem to bother the chinstrap penguins. Instead, it helped them protect their budding young families.

It snows in the oceans. Bacteria, the skin cells of fish, fish poop, and bits of sand and dirt all clump together. These “snowflakes” can be up to an inch or two across. Many of them are eaten as they sink toward the ocean floor. But others float all the way to the bottom—a trip that can take weeks. The snow falls all the way down even in the deepest waters, where the pressure can be a thousand times the surface pressure or greater. In fact, a recent study suggests the pressure might actually help the snowflakes survive in the deep ocean. Scientists in Denmark made their own version of marine snow. They then put some in several different tanks. They rotated the tanks so that the snow was always “falling.” And they increased the pressure in the tanks every day. They then opened some of the tanks when the snow had reached different “depths” to see how much had remained intact. Down to the equivalent of about four miles, the snowflakes gradually fell apart, and the living bacteria basically shut down. Below that depth, however, the process stopped—the flakes held together. By the time they hit about six miles—deeper than more than 99 percent of the world’s oceans—about half of the original flakes had survived. Marine snow is the main food source for much of the life on the floor of the deep oceans. It also socks away carbon from the atmosphere, helping reduce global warming. So about all we can add is this: Let it snow, let it snow, let it snow!

Killer whales near the Atlantic coast of Spain and Portugal have been living up to their name. From May 2020 through the end of 2023, they “killed” four boats and attacked hundreds of others. Marine biologists are still trying to explain why. They’re not the first reported whale attacks in that part of the world. In fact, the earliest known attacks anywhere took place in the northeastern Mediterranean, near Constantinople. Those attacks were blamed on a single whale: Porphyrios. The attacks took place about 1500 years ago. They lasted for 50 years. The attacker might have been a sperm whale, although orcas—killer whales—are more common in that region. Porphyrios attacked all types of boats. Sailors traveled around its home waters to avoid the danger. Most of the recent attacks have involved sailing vessels. Orcas approach from behind a boat and ram into the rudder, disabling the craft. They sometimes hit the hull as well, poking holes that sink the boats. All of the attacks have been near the coast or in the Strait of Gibraltar. They may have been started by a single female, named White Gladis. The groups often are led by a larger orca, with smaller, younger ones learning from their elder. Scientists have speculated that White Gladis was injured in a collision with a boat, or entangled with a fishing net, and was after revenge. Others say it’s just a fad—a type of play that’s passed from whale to whale—a scary fad for sailors.

According to an old saying, a rising tide floats all boats. And in the decades ahead, rising waters will threaten all coastal cities. As our planet gets warmer as the result of human activities, sea level is rising. So cities along the coast will see more flooding—more often, with higher water levels. But a recent study says the risk isn’t the same for everyone. Researchers calculated the possible effects of climate change combined with natural fluctuations in sea level. That included El Niño, tropical cyclones, and other events. They used a temperature increase at the high end of current predictions, then compared their numbers to conditions in 2006. They found that, by the end of the century, the combination could boost the risk of coastal flooding around the world by 20 to 30 percent compared to global warming alone. The study said the risk will go up for most coastal cities, including those in the United States and Australia. New York, for example, could see 18 times more flooding events with climate change alone, but 25 times more when natural events are factored in. The numbers are even higher in Bangkok, Manila, and other major cities in Asia. Manila, for example, could see 18 times more floods with climate change alone, but 96 times more with the combo. And those same Asian cities would have to build much more extensive defenses to protect themselves—from the combined impact of Mother Nature and human-produced climate change.