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What's that rust color atop of Kachemak Bay waters in Alaska?

McKibben Jackinsky | Homer News

HOMER -- Earlier this month, Catie Bursch, marine educator and illustrator for the Kachemak Bay Research Reserve, began getting calls about something red in the water. Some callers worried it was red tide, a common term used to describe a harmful algal bloom.

Bursch knew where to turn to solve the mystery.

"I coordinate a program where locals volunteer to collect water samples to look for toxins that could result in toxic shellfish," said Bursch. "It's cool because I have this volunteer pool I could call for samples from around the bay. And I got them very quickly."

She also received word quickly of the spread of the unidentified substance. Sightings came in from Whiskey Gulch, north of Anchor Point; Bear Cove, toward the head of Kachemak Bay; and from communities on the south side of Kachemak Bay.

"People were even reporting it on lakes in Kenai and Soldotna," said Bursch. Through Bursch's connections in the scientific community, she began closing in on the answer.

"Conrad Field, a well-known naturalist here in town, said, 'You know, there's this rust stuff on spruce trees,’ " said Bursch. "Then we got an email from the (National) Park Service, and they'd seen it in Lake Clark last year. It was the same thing that was in the news last year in Kivalina. They were calling it 'orange goo.'"

The U.S. Forest Service and the Canadian Forest Service eventually fingered the culprit in Kivalina: spores from Spruce-Labrador Tea Needle Rust. The rust colors both spruce tree needles and Labrador tea leaves orange, and relies on both hosts to thrive. There's plenty of Labrador tea around Kivalina,

Forest Service experts were pretty certain the rust spores caused the colored water, in part because the state has a history of large outbreaks of the spruce-rust, Robin Mulvey, a forest pathologist in Juneau, told Alaska Dispatch earlier this year. Using a scanning electron microscope, an expert determined that the spore's physical characteristics showed it indeed was Spruce-Labrador tea needle rust. The expert determined it came from spruce needles, not Labrador tea leaves, said Mulvey, who with the division of Forest Health Protection.

In Homer, a close look at a spruce branch indicated the substance wasn't coming from the tree itself, but from a fungus that uses the spruce as a host.

The answer: Chrysomyxa ledicola Logerh, more commonly known as spruce needle rust.

"This stuff kind of forms little blisters on the new needles. It loves the new needles, not the old ones," said Bursch.

The life cycle of spruce tree rust begins with two seasons on a Labrador tea plant before moving on to a spruce tree.

"It likes temperatures under 60 degrees and a wet summer," said Bursch. "Then, when it warms up, those blisters come open and it releases the spores and starts the cycle all over again."

Bursch's findings have been verified by a plant pathologist with the U.S. Forest Service. Is it something to worry about?

"No. It's a natural, harmless plant fungus," said Bursch.

The spruce tree rust should not be confused with spruce tree pollen. "But that happens earlier in the year," said Bursch.

"Sometimes toxic algal blooms are red and sometimes they're not, so (color is) not a real good indicator, but everybody kind of knows about red tide and worries about it," she said. "That's why we had so many calls, but this had nothing to do about that."

Nevertheless, Bursch said residents shouldn’t hesitate to contact her.

"We like having the role of being the go-to place. That's our mission: to study Kachemak Bay and educate about it," she said. "So if there's something on the bay, we like to figure out what it is."

For more information about spruce tree rust, visit here  here or here.   :

Used with permission from the Homer News. Contact McKibben Jackinsky at mckibben.jackinsky@homernews.com.