Reddish-brown patches in the water of Gastineau Channel as seen from the Douglas Bridge on Tuesday, July 31, 2018. (Michael Penn | Juneau Empire)

Reddish-brown patches in the water of Gastineau Channel as seen from the Douglas Bridge on Tuesday, July 31, 2018. (Michael Penn | Juneau Empire)

Possible algae increase dyeing Gastineau Channel waters red

No reason to believe it’s dangerous, scientists say

Eric Prestegard saw it for the first time Sunday.

A shade of rust-colored red crept its way through the waters of Gastineau Channel as Prestegard, the executive director of Douglas Island Pink and Chum (DIPAC) Inc. watched and worried. This is a vital time of year for the hatchery, which is midway through its egg taking process, Prestegard said.

Two days prior to that, the Alaska Department of Environmental Conservation had gotten a call that something unusual was floating around in the channel. Dave Pikul, an environmental program specialist for the Southeast Region’s Spill Response Unit, went down to the water and took a look.

“It was pretty widespread,” Pikul said. “Our observations down at the shoreline identified it was not oil, but it was some kind of biological mass.”

Exactly what that biological mass is, however, is still yet to be determined. Kate Kanouse, a habitat biologist for the Department of Fish & Game, said the overriding current theory is that it’s an algae bloom, or algal bloom. An algae bloom is a rapid increase in the amount of algae in the water, usually brought on as a result of rising water temperatures.

“That’s the most likely cause,” Kanouse said. “We’ve had a nice warm summer and it fits the criteria of what we would see of an algal bloom. I wouldn’t expect it to be anything else, and I don’t expect it to be dangerous.”

Algae blooms can be harmful, but not all of them are, according to the National Ocean Service. Vera Trainer, a research oceanographer with Northwest Fisheries Science Center, said blooms can cause a lack of oxygen in the water, which can kill small fish. More commonly in Alaska, she said, blooms affect shellfish.

“The most common in Alaska that are known of right now are the paralytic shellfish poisoning events that are resulting in accumulation of toxins in shellfish that can then be dangerous to humans,” Trainer said.

Trainer said algae blooms in Alaska are old news, as Aleuts have known about toxic shellfish for generations. Trainer said people should pay attention to health authorities’ websites and announcements about shellfish.

For many in Juneau, the reddish hue of the water is a new sight. Prestegard said he can’t remember a time when algae or phytoplankton were this widespread, even in the hot summer of 2004.

As he’s watched from his spot along the channel, Prestegard said that so far, everything seems to be fine.

“We’ve observed it the last three days,” Prestegard said. “At this point, it doesn’t seem to be affecting our fish in any way, shape or form.”

Prestegard said they’re a bit concerned about their aquariums, though. While the fish seem to be holding up well, DIPAC employees aren’t certain that smaller animals will be so immune. Prestegard said the algae bloom — or whatever it might end up being — has not made its way right up to the hatchery quite yet, but they’re watching closely.

Trainer said blooms will likely become more and more common in Alaska as ocean temperatures continue to rise. As ice melts, she said, sunlight will penetrate the water easier and promote more growth among plant life such as algae.

“Certainly with warming water,” Trainer said, “there’s going to be a larger suite of algal bloom problems that can occur in Alaska.”


• Contact reporter Alex McCarthy at 523-2271 or amccarthy@juneauempire.com. Follow him on Twitter at @akmccarthy.


More in Home

X’unei Lance Twitchell teaches an advanced Tlingít course at University of Alaska Southeast on Monday. (Claire Stremple/Alaska Beacon)
Alaska Native languages at crucial juncture, biennial report says

Call to action urges systemic reforms to the state’s support and integration of Native languages.

Reps. Jesse Sumner, R-Wasilla, and Jamie Allard, R-Eagle River, talk to Speaker of the House Cathy Tilton, R-Wasilla, during a break in the Alaska House of Representatives floor session on Monday. (James Brooks/Alaska Beacon)
Entering their final two regular weeks, Alaska legislators are narrowing their focus

Dozens of firefighters protested outside the Alaska Capitol last week, waving signs… Continue reading

Juneau residents calling for a ceasefire in Gaza put on t-shirts with slogans declaring their cause before testifying on a resolution calling for “a bilateral peace agreement in Israel and Palestine” considered by the Juneau Assembly on Monday night. (Mark Sabbatini / Juneau Empire)
Juneau Assembly fails by 2-5 vote to pass resolution seeking ‘bilateral peace’ between Israel and Palestine

Members question if declaration is appropriate at local level, angering residents favoring ceasefire

The Juneau-Douglas High School: Yadaa.at Kalé boys soccer team takes on Palmer High School on Friday in Anchorage. (Photo by Tory Bennetsen)
All four Juneau high school soccer teams notch winning records during road trip north

JDHS girls remain undefeated; both TMHS teams get first victories of season.

Nils Andreassen and his sons Amos, 7, and Axel, 11, pick up trash in the Lemon Creek area during the annual Litter Free community cleanup on Saturday morning. (Mark Sabbatini / Juneau Empire)
Annual community cleanup is its own reward — and then some

Nearly 800 people pick up tons of trash, recyclables and perhaps treasures

Debris from a home that partially fell into the Mendenhall River sits on its banks on Sunday, Aug. 6, 2023, after record flooding eroded the bank the day before. (Mark Sabbatini/Juneau Empire file photo)
Alaska Senate unanimously OKs increasing maximum state disaster relief payments and eligibility

Bill by Jesse Kiehl, D-Juneau, raises limit to $50K instead of $21K, makes condo residents eligible

Kaxhatjaa X’óow/Herring Protectors wearing robes, which will be part of the exhibit “Protection: Adaptation & Resistance” at the Alaska State Museum on Friday. (Photo by Caitlin Blaisdell)
Here’s what happening for First Friday in May

Exhibit by more than 45 Alaska Natives at state museum features protector robes, MMIP Day preview.

The Matanuska state ferry, seen here docked when it was scheduled to begin its annual winter overhaul in October of 2022, has been out of service ever since. (Alaska Department of Transportation and Public Facilities photo)
State awaits report, cost estimate on repairing Matanuska state ferry — and if it’s worth the effort

Full-body scan of vessel, out of service for 18 months, will determine if ship should be scrapped.

Lon Garrison (center), executive director of the Alaska Association of School Boards, presides over a Juneau Board of Education self-assessment retreat Saturday at Dzantik’i Heeni Middle School. (Mark Sabbatini / Juneau Empire)
School board president says she won’t run again at meeting where members assess their response to crisis

Deedie Sorensen says it’s time to retire as board members give themselves tough grades, lofty goals.

Most Read