Massive marine die-off in Russia could threaten endangered sea otters, other vulnerable species

September 14 was a rare sunny day at Khalaktyrskiy Beach. A seaward wind was whipping up the waves, and at 54 degrees Fahrenheit, the water was warmer than even the air. Conditions were ideal for surfing, at least by the standards of the “land of fire and ice,” Russia's Kamchatka Peninsula, in the far east.

But half an hour after Katya Dyba, an administrator at Snowave, a local surf school on the Pacific coast, came in from riding the crests, her vision began to blur, and her throat became sore. One of her co-workers couldn't open his eyes.

The surfers first blamed it on the sun’s glare or buffeting winds. As they began to suffer nausea, vomiting, diarrhea, and fever in the ensuing days, however, they realized the poison was in the ocean itself. In total, 16 people went to the hospital; several were diagnosed with corneal burns.

Meanwhile mounds of lifeless sea urchins and starfish were washing up on Kamchatka’s eastern shores. Beachgoers picked up limp red octopuses by their tentacles. A patch of fetid yellowish foam hundreds of feet wide and several miles long floated down the coast. Divers estimated that in some places, 95 percent of bottom-dwelling organisms had perished.

“My reaction was absolute bewilderment, because we’re used to the water at Khalaktyrskiy Beach always being very clean, and nothing like this had ever happened before,” says Dyba, who is still suffering eye dryness a month later.

The problem has spread southwest, around the peninsula and up the food chain: Thousands of dead fish, mostly bottom feeders, were found on Kamchatka’s western shore this week, and several brown bears suffered severe food poisoning after eating them—just one example of the potential ripple effects this mass marine life die-off could cause.

While many initially suspected pollution, scientists now say the deaths were probably caused by an algal bloom. That raises even more troubling questions about how climate change is affecting one of the planet's most biodiverse marine environments, home to endangered species such as steelhead trout and sea otters.

“We didn’t expect that the area of algal blooming [would] be so massive,” says Kirill Vinnikov, a marine biologist at the Far Eastern Federal University. “It is an unprecedented case.” (Last year, National Geographic chose Kamchatka Peninsula as one of its best trips of the year.)

‘The whole coastal zone is infected’

Hanging off Russia’s Pacific coast like a droopy tail, Kamchatka has the highest concentration of active volcanoes on Earth. Rivers cascade from these lava fields and glaciers into broad marshes and form the perfect spawning grounds for six species of ocean-going salmon, which in turn provide food for brown bears, spotted seals, orcas, and decreasing numbers of Steller’s sea eagles and Steller’s sea lions. The salmon often feed on zooplankton in the nutrient-rich Kamchatka current, as do gray whales and critically endangered right whales.

While Kamchatka is synonymous with salmon, it also has a huge variety of bottom-dwelling fish, mollusks, anemones, sea stars, and sea urchins that sustain mammals like walruses and otters. Unable to swim away from contaminated waters, these bottom-dwelling organisms have been dying in the greatest numbers.

“A vital element of this ecosystem has suddenly fallen out,” says Vasily Yablokov, Greenpeace Russia’s climate project manager, who has been taking samples in Kamchatka.

While scientists quickly excluded volcanic activity as the cause of the marine die-off, samples taken at Khalaktyrskiy Beach found that levels of phenol, iron, oil products, phosphate ions, and mercury were several times higher than normal. But none of these concentrations, nor the wastewater dumped by a passing ship on September 23, seemed large enough to explain the sweeping die-off. Officials also ruled out leakage from a nearby pesticide dump and a military testing site.

Last week, scientists flew over the coast looking for clues. They spotted swaths of yellow, green, and red water suggestive of an algal bloom. These microscopic phytoplankton produce as much as half the world’s oxygen, but certain species can grow out of control when nutrients in runoff “overfeed” them or water temperatures increase. When this happens, they emit toxins and deplete oxygen levels in the water as they die and begin decomposing on the seafloor. That could explain high mortality among Kamchatka’s bottom-dwellers, Vinnikov says. (Learn more about algal blooms and red tides here.)

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“We flew 100 kilometers to the south of Kamchatka, and we observed this kind of discoloration of the water almost along the whole coastal area,” he says. “The whole coastal zone is infected.”

Water and sediment samples later found DNA from several species of Gymnodinium algae, whose toxins are known to irritate the human nose and throat. While the concentrations weren't high, satellite imagery in late September also showed that the amount of chlorophyll—the photosynthetic pigment in plants and algae—in Avacha Bay, on the southeastern side of the peninsula, was double the monthly average, according to Raphael Kudela of the University of California, Santa Cruz.

Red tide, red alert

Algal blooms are not uncommon in Kamchatka. This presumed event, however, was more extensive and longer lasting than any in recent memory, Vinnikov says.

Along with the invertebrates, dead salmon, the foundation of both the local food web and economy, have washed ashore too. This time of year, coho salmon are coming in from the ocean to head upstream to spawn—and potentially passing through the red tide.

“Fish swimming in that area at the time of the bloom, if it is large enough, would likely be affected and possibly die from acute exposure to a powerful toxin,” says Woods Hole senior scientist Don Anderson. But ocean mixing could quickly clear the water of contamination, he adds.

Fish, zooplankton, and bottom-dwelling organisms at the bottom of the food chain can pass algal toxins up to predators, such as walruses and whales, or simply deprive predators of food when there are massive die-offs due to oxygen depletion. (See pictures of extreme algal blooms worldwide.)

To date, far more sea urchins have died than fish, raising concern about the survival of the sea otter, for whom sea urchins are a staple. After the Soviet breakup opened the peninsula to intensive fishing, the otter's population plummeted from thousands to an estimated 200 in southern Kamchatka today. The decrease in sea urchins could “very negatively affect the number of this species,” says Vladimir Burkanov, a lead scientist at the Kamchatka branch of the Vladivostok-based Pacific Geographical Institute, because sea otters are less likely than other marine mammals to travel to find food.

According to Anderson, Kamchatka authorities should keep investigating signs of chemical pollution, which might have contributed the nutrients that triggered the presumed algal bloom. Addressing pollution would be an easier and more immediate fix than trying to mitigate the primary cause behind an expected increase of red tides globally—climate change.

While the Arctic is increasingly vulnerable to algal blooms, there isn’t enough data yet to tell if that is the case in sub-Arctic Kamchatka. “In a general sense, warmer waters lead to more of these kinds of blooms, but it’s really complicated,” Anderson says. “Warmer waters might push some species [of algae] away from this area and shift their range north.”

Scientists are now calling for more water quality monitoring in Kamchatka after what Burkanov calls both “a red tide and a red alert.”

“If it’s really a red tide of a scale never observed before, then it's a real warning,” he says. “And that’s even worse than local pollution from some chemicals.”