Photograph by Aleta George SEABIRD SANATORIUM: Pelicans recover poolside at the International Bird Rescue Research Center in Cordelia in late January.
A potent algal neurotoxin could threaten California's brown pelicans just as officials move to delist them
By Aleta George
When word came to the Central Coast WildRescue center this winter that California brown pelicans were showing up in the mountains or wandering on roads far from the sea, wildlife paramedics set out to find them. They saw dozens of dead ones in the greater Monterey Bay area, said WildRescue founder Rebecca Dmytryk. Those that were still alive acted "down," a term used to describe a bird that is not bright and alert. The 28 surviving pelicans were carefully captured and transported to the International Bird Rescue Research Center in Cordelia at the northern end of San Francisco Bay.
During what came to be known as the "pelican mortality event" this winter, at least 500 pelicans were reported dead or debilitated along the West Coast from Astoria, Oregon to Baja California. Some showed signs of disorientation and some were found in odd places, such as a mountain in New Mexico. Many had severe frostbite on their pouches and feet, leading scientists to believe that the cause of the event was likely related to climate change. With unseasonably warm fall weather in the Pacific Northwest, some 5,000 pelicans had lingered at their summer and fall roosting sites in northern Oregon. When a freezing winter storm hit in mid-December, they were forced to migrate in harsh conditions that included 60 mph winds.
During the event, scientists, vets and rehabilitators shared notes and tested the dead birds. San Diego's Sea World performed necropsy exams on eight to 10 birds. The U.S. Geological Survey National Wildlife Health Center in Wisconsin tested four. Tests were also run at the California Animal Health and Food Safety Lab at UC Davis and the California Department of Fish and Game's Marine Wildlife Lab in Santa Cruz. The birds tested negative for avian influenza and West Nile virus, and though there were a few birds that tested positive for domoic acid—a type of harmful algae bloom that has been the cause of bird and marine mammal mortalities since its discovery in 1991—but the levels were low.
David Jessup, senior wildlife veterinarian for the California Department of Fish and Game, compiled information from pathology reports, transect counts and observations from field biologists and clinicians. What he found was a variety of signs and symptoms that weren't consistent. The findings led him to state in an interim report that the December storm seems to have been the primary cause of the event, but it doesn't account for all observations or findings. "Some other causes of illness and death remain unexplained," he wrote.
One thing researchers didn't test for was saxitoxin, one of the most potent natural toxins known. Saxitoxins are a family of single-celled naturally occurring dinoflagellates that cause paralytic seafood poisoning (PSP) in humans.
Maybe they should have run those tests. While the pelicans dive-bombed for fish in Oregon's late Indian summer weather, the entire coast of Oregon was closed to mussel harvesting due to elevated levels of PSP toxins. Is it possible that PSP toxins were a factor in the pelican mortality event?
"It's highly possible," says Matt Hunter, shellfish project leader of the Oregon Department of Fish and Wildlife, "but without testing it's hard to say."
Why didn't they test the birds for saxitoxin? For one, as of late February, Jessup wasn't aware of the mussel-harvesting closure. Perhaps that's because there wasn't a big red-tide event that covered multiple counties like the one California had in 1991. Gregg Langlois, a senior environmental scientist with the California Department of Public Health, had just started his job in 1991 when he witnessed a saxitoxin-laced bloom, or red tide, that covered Marin County's Drake's Bay. (Physical discolorations in the water are referred to as blooms, but not all visible blooms are toxic.) There wasn't a bloom in Oregon this winter, just mussels with enough toxins in their flesh to warrant a ban on harvesting.
Along the West Coast, PSP toxins are associated with upwelling and can threaten human health and coastal economies. To help keep the public safe, shellfish are tested regularly. In California, shellfish are monitored for neurotoxins year-round, in addition to seasonal quarantines. In Oregon, the Department of Agriculture (ODA) tests razor clams, oysters and mussels for PSP toxins and domoic acid, both of which can cause minor illness and more serious problems leading to death. If the bivalves tested show 20 parts per million for domoic acid or 0.8 parts per million for PSP (80 µg/ 100 g), the area is closed to harvesting for a minimum of two weeks.
"The closures are not unusual," says Sarah Schwab, a food-safety specialist with the ODA. "What is unusual is the length of time the beaches were closed to harvesting this fall and winter."
The ODA closed the entire coastline of Oregon to mussel harvesting on Oct. 10, 2008, and didn't deem harvesting safe until Jan. 20, 2009, when they reopened the beaches. The highest spike in PSP toxins found was on Nov. 10 in northern Oregon at Silver Point, with 441.4 µg/100 g, and at Cape Meares, with 384.6 µg/100 g, four to five times the threshold amount. Both locations are south of the Columbia River and within foraging range of East Sand Island, the largest communal pelican night roost north of the Farallon Islands.
The numbers seen in Oregon don't reflect mussels that are particularly "hot," according to Hunter. To put the numbers into perspective, the 1991 PSP red tide seen by Langlois in Marin County topped out at 10,000 µg/100 g.
But it's possible that even relatively low concentrations are dangerous to wildlife. It's unknown how sublethal exposure affects a bird's long-term health. "We don't have a handle on the lethal dose of toxins for birds," Langlois says. "It's just a black hole."
Paralytic seafood poisoning toxins are known to bioaccumulate in shellfish, like mussels and razor clams, but not necessarily in pelagic fish like sardines and anchovies. "Normally, we think of PSP toxins as showing up in shellfish," says Raphael Kundela, a professor in ocean sciences at UC Santa Cruz, "but many organisms eat phytoplankton, including fish."
In an article in the January 2009 issue of Harmful Algae, a group of scientists reported that they found the first evidence of PSP toxins in northern anchovies and Pacific sardines in Monterey Bay and some California coastal regions. Pelicans don't eat shellfish, but they do eat sardines and anchovies.
A New Threat
California brown pelicans are getting ready to fly off the state's endangered species list. In early February, the state Fish and Game Commission voted to take them off the list where they have been since 1971. If approved by the Office of Administrative Law, the pelican will be the first endangered species in the state to be delisted due to recovery. Their numbers have now reached 8,500 pairs.
As pelicans fly into the sunset with their eight-foot wingspan, harmful algae blooms are increasing with virility around the world. Scientists aren't certain why, but suspect increased nutrients from agricultural runoff and human waste, changes in the climate and the movement of algae in ballast water. In California, there has been a sea change in the dominant phytoplankton community since 2004, says Kundela. Dinoflagellates are on the rise. Scientists don't know the reason for this either, he says, but they suspect that with less upwelling and warmer surface water, conditions are selecting for more dinoflagellates. Oregon's waters are changing, too. "When I first started 14 years ago, PSP was a summertime event and domoic acid was a cooler water, winter event," says ODA's Dawn Smith. "That's not the case anymore. We're now seeing PSP in the dead of winter."
The good news is that the West Coast is well monitored and regulated. As a result, there hasn't been a human illness caused by PSP in the last decade.
The bad news for pelicans and other seabirds is that they can't read the posted signs or check their emails for notices of harmful algae blooms. They gulp what they see, and as an indicator species, communicate what's going on in our oceans.
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