Environment
WHITTIER, Alaska — David Irons, a biologist who specializes in Alaska seabirds, was checking on a friend’s boat in Whittier, a coastal community south of Anchorage, on New Year’s Day when he spotted a line of white dots along the beach. He walked down to investigate.
“There were just dead murres everywhere. It was incredible,” he said. “I estimated 8,000 birds in a little bit more than a mile.”
Common murres are sharp-billed black-and-white seabirds that feed on small fish. In the weeks after Irons’ discovery, scientists and volunteers found thousands of dead and dying murres on Alaska beaches, the largest murre die-off on record. Sick murres also began to turn up in Alaska's interior, hundreds of miles from the ocean.
The massive seabird die-off is part of a larger story about the health of Alaska’s oceans as sea temperatures rise. For more than a year, scientists have been cataloging smaller, unexplained episodes of animals dying on beaches — including other birds, sea otters, sea lions, several species of whales, starfish and fish. In all cases, the suspected cause of death has been linked to warmer sea temperatures, and some scientists suspect there is also a connection to the toxic algae that thrive when temperatures tick up even a few degrees.
“We are having water that is 5 degrees [Fahrenheit] warmer over a huge area. At the same time, we are having these unusual mortality events,” said Heather Renner, a supervisory wildlife biologist at the Alaska Maritime National Wildlife Refuge, which encompasses 2,500 coastal Alaska islands. “We don’t have any proof they are linked, but they are happening at a time when the ocean is warmer than it’s been for ages.”
Alaska had its warmest year on record in 2014 and its second-warmest year in 2015. What is happening in Alaska’s oceans right now can’t be directly connected to climate change, but it is part of a long-term trend, said Rick Thoman, a climate sciences and services manager with the Alaskan branch of the National Weather Service. Northern waters were warmer than average to begin with last year, and they are now being affected by El Niño, which fuels big thunderstorms in the tropics and injects massive amounts of water and energy into the atmosphere. This affects the jet stream and in turn can affect northern weather, he said.
Toxic algae are always present in Alaskan oceans, but elevated temperatures have recently spurred massive blooms. Last year scientists observed the largest algal event ever seen in satellite pictures in the Gulf of Alaska, said Bruce Wright, a senior scientist with the Aleutian Pribilof Island Association. “It was just green,” he said. “And it was dominated by harmful algae.”
His theory is that algae play a significant role in animal deaths by disrupting the food chain. “I think the toxins are working their way through the food web … sickening or killing top predators, including sea lions [and] Yukon River king salmon,” he said. Although not all scientists agree with this, on Feb. 11 the National Oceanic and Atmospheric Administration (NOAA) announced that a new study found toxic algae “are present in Alaskan food webs in high enough concentrations to be detectable in the ecosystem’s marine mammals, from the Arctic Ocean through the Bering Sea to the Gulf of Alaska.”
The agency warned Alaskans not to eat marine mammals that look sick or act uncharacteristically. This poses a problem for rural Alaska Natives, many of whom rely on protein from whales, seals and walruses. Additionally, high levels of algal toxins have been found in shellfish around Alaska, prompting health warnings about the potential for mussels and clams to induce paralytic shellfish poisoning.
“We’ve been hearing from communities that they aren’t harvesting because there is either algal bloom or they are worried about it,” said Ali Hamade, an environmental public health program manager with the state.
In the case of the murres, scientists studied over 100 carcasses and determined the most common cause of death was starvation. Wright suspects the algae may have affected the birds by killing off fish. Irons hypothesizes that the higher water temperatures also may have changed the distribution of small fish in the ocean, putting them out of reach. “There either isn’t any food or it was bad food,” he said.
Since last summer, humpbacks, fin whales, sperm whales and gray whales have been washing up dead in the Gulf of Alaska, according to the NOAA. Two dead whales washed up on St. George Island just recently. “About 45 whales have been discovered — more than three times the average,” said Julie Speegle, a spokeswoman for the NOAA in Alaska.
In the Aleutian Islands, Wright said, the Steller sea lion population is down by 90 percent, and the animals are in danger of extinction. Aleutian sea otters and seals have also seen significant declines in recent years.
Some recent animal die-offs are harder to explain. In Kachemak Bay, south of Anchorage, dozens of sea otters washed up on beaches last fall. Their deaths were linked to a bacterial infection, but, Wright said, stresses caused by toxic algae that were in their food or made it harder for them to find food could have compromised their immune systems. A rash of sea stars stricken with a wasting virus in the same area was linked to warmer water.
When temperatures change rapidly, it takes animals some time to adapt, he said. There can be years of adjusting.
“It’s anybody’s guess what this will look like at the other end,” Wright said.
Irons said that the seabird die-off is a good indicator that scientists should look at the health of the animals the birds eat.
“Kind of like the canary in the coal mine, this is the canary in the ocean,” he said. “The seabirds are telling us something is wrong out there.”
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