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Murder in the Muck: Scientists Search for Clues to a Killer in the Eel River

November 20, 2014
by Sabine Bergmann
Scientist standing a river observing an algae bloom

In a long, rectangular laboratory with windows facing a dim October sky, Keith Bouma-Gregson casually shows me his collection of murder suspects.

“This was sent to me by a woman,” he says, extending a mason jar of toxic pond scum. The jar is filled with a dark-green thicket of algae, which is emitting tiny streams of bubbles into the sloshing liquid. The contents are nearly identical to the mats filling a foot-long fish tank in the refrigerator behind Bouma-Gregson, a Ph.D. candidate at UC Berkeley.

It’s impressive: Not one, but both of the lab fridges are filled with shelves of petri-dishes and glass vials, the contents of which are everywhere along the blue-green-cyan color spectrum. Noting a petri-dish smeared with grassy algae, Bouma-Gregson explains that the colonies sprouted up quickly, in a matter of days.

If this is the culprit that he’s looking for, it contains a potent neurotoxin that causes seizures in 5-10 minutes, and death in less than an hour.

Blue-green algae, or cyanobacteria (so-named for their occasional cyan color), have been around for approximately 3.5 billion years, but didn’t cause much alarm in Humboldt County until 2001. Then they claimed their first victims.

That summer and early fall, as families flocked to the Yacht Club at Big Lagoon to enjoy the sun, something tragic starting happening with the dogs. As Heather Muller described in an interview with the North Coast Journal Weekly, her 6-year-old white mutt, Ernest, began vomiting not long after frolicking in the blue-green foam at the lagoon’s shore. At first, Muller wasn’t too concerned (“That’s what dogs do—puke”), but as Ernest stopped eating or drinking it became clear that he was in serious trouble. Muller took her shaking, dehydrated pet to the vet, where he was diagnosed with liver failure. Within days of his bath in the algal bloom, Ernest died.

Underwater photo of a river

Between July and October of that year, four other dogs ultimately perished from bouts of vomiting, bleeding, diarrhea, dehydration and liver failure. One dog, it was noted in a fact sheet prepared by Humboldt’s Division of Environmental Health, emerged from the water “covered in green slime.”

Humboldt’s DEH took water samples from the lagoon that November and tested them for microcystin hepatotoxins—common liver toxins produced by algal blooms. “It’s one of the more common [algal] toxins,” Bouma-Gregson says. “In Lake Erie when they get the big bloom up there, it’s often a microcystin toxin—a liver toxin.”

It made perfect sense for Humboldt’s DEH to test water samples for microcystin hepatotoxins—especially since the dogs seemed to be dying of liver damage. Though the samples were taken a month after the last incident, meaning the toxins might have dissipated, there was every reason to expect the samples to come back positive.

They came back negative.

The next year, around the South Fork of Humboldt’s Eel River, three more dogs died. Alarmingly, this time they suffered from neurological symptoms.

The dogs started seizing within 5 to 10 minutes of exposure. Cardiopulmonary resuscitation performed at the local veterinary hospital proved futile. An unidentified (but clearly strong-stomached) person collected what the dogs regurgitated during the failed CPR and saved it for testing.

When the California Animal Health and Food Safety Laboratory System analyzed these stomach contents, they found “green plant-like material” along with something new: anatoxin-a.

Unlike microcystin, anatoxin-a is a neurotoxin—it attacks the brain. And if the Eel River poisonings are any indication, there’s not much that can be done to stop it.

In 2008 Birgit Puschner of UC Davis published a paper in the Journal of Veterinary Diagnostic Investigation describing the poisoning of the dogs in the Eel. In the report, Puschner notes gravely, “It appears that treatment of anatoxin-a poisoning is of little or no benefit, and the outcome is usually lethal.”

It was the first documented report of anatoxin-a dog poisoning in North America.

That ex­plains why dogs were dy­ing when people wer­en’t: People don’t gen­er­ally drink river wa­ter (or lick it off of their skin, for that mat­ter).

Eleven dogs have died so far.

Humboldt County has launched an educational campaign outlining the risks of algal blooms. In years when conditions favor warm, stagnant water—a general precursor to the algal blooms—it posts warning signs along the rivers, and hosts community outreach events.

“Since I’ve been here,” says Shannon Hinrichs, an environmental health specialist there since 2009, “it’s been every year.”

When Bouma-Gregson and his volunteers wade out into the Eel to install their sampling equipment, it’s not in protective suits and gloves. “It’s usually chacos (river-shoes) and shorts,” says Bouma-Gregson, casually mentioning how he sometimes dips his face into the water or sends ‘his undergrad’ into big mats of floating algae. As for specialized gear, “I’ve got a very fashionable waist-pack that I carry with me.”

Most of the algal toxins, Bouma-Gregson explains, are molecules floating around the cyanobacteria cell. In other words, the algae are only toxic when ingested—through swallowing the water or, often in the case of dogs, licking it off of their fur. That explains why dogs were dying when people weren’t: People don’t generally drink river water (or lick it off of their skin, for that matter). Still, children play in the river. And several people have contacted Bouma-Gregson about skin rashes that may be linked to the blooms—including the woman who sent him the pond sample.

Bouma-Gregson samples his sites using SPATT—Solid Phase Absorption Toxin Tracking—rings, two and a half inch circlets coated with resin. He places them in free-flowing water, and the toxins that float through the rings glom on to the resin. When he takes his SPATT rings out of the Eel, Bouma-Gregson extracts the toxins and measures their concentration. Unlike grab samples, which offer a snapshot of a river’s toxicity, SPATT rings show how toxicity changes over time. Bouma-Gregson wants to get an idea of how the river’s toxicity is changing, so that he can start to nail down what’s causing it to go toxic in the first place.

He still has a ways to go before publication, but he did hint at the results: “It can be quite dynamic—[concentrations have] jumped up real big and then dropped down and jumped up again.” He adds that these spikes may have something to do with changes in environmental conditions, but that one can only speculate as to what’s caused the changes.

Pat Higgins, fisheries biologist with the Eel River Recovery Project, has a few hypotheses for why 3.5 billion year old algae are suddenly taking over the Eel.

One driver may be drought. Higgins points to the 1986-92 drought as a possible “tipping point” for warming the river—“Whoops,” he says, “Blue green algae likes warm water.” The recent drought has caused even warmer, shallower waters in the Eel. In the summer of 2014, Bouma-Gregson and his volunteers set up their SPATT rings in water less than knee-deep. And in September, the mainstem of the Eel was so drought-parched that it stopped flowing for the first time in recorded history.

Another driver may be an influx of nutrients. Normally, the Eel doesn’t have enough phosphorus to sustain large algal blooms. But if phosphorus is added to the river through fertilizer run-off, for instance, then there’s not much stopping the algae. The fertilizers, Higgins says, probably come from the recent surge in rural agricultural enterprises.

“We don’t need to name them,” he says, “but everyone does—marijuana—and not all practitioners of rural agriculture are conscious.”

Higgins emphasizes that his theories about drought and pot farm run-off are just that: theories. And he notes that a lot of Humboldt’s marijuana growers use “harmony-based practices.”

As the case continues to unfold, it may be tempting to think of Bouma-Gregson and his colleagues as sallying forth into the battle of man vs. algae.

Keith Bouma Gregson pulling algae out of a river
Keith Bouma Gregson peruses the Eel River

“No,” Bouma-Gregson says, “Algae is not this monolithic thing that’s scary. It can be quite beneficial.”

He points out that his faculty advisor, Mary Power, has conducted research that establishes nutritious edible diatoms as the base of the Eel’s food web. It turns out that the good-guy algae are responsible for maintaining populations of fish and dragonflies and turtles that people flock to the Eel to see. Toxic blooms have given algae a bad rap, but they’re just a manifestation of an ecosystem out of balance.

“What we want,” Bouma-Gregson says, placing the jar of pond scum back into the sample-stuffed fridge, “is to keep our aquatic food web making fish and turtles and insects and not making cyanobacteria toxins.”

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