Daily Sitka Sentinel

No Danger Seen in Sitka’s Bright Green Seas

By GARLAND KENNEDY
Sentinel Staff Writer
    Toxic algae blooms have long been a health concern in Southeast Alaska, and a dramatic bloom that’s  turning the water in Silver Bay bright green has stoked new concerns that local shellfish may be unsafe to eat.
    But researchers at the Southeast Alaska Tribal Ocean Research Center in Sitka say that this particular bloom is not dangerous.
    The Sentinel spoke with Naomi Bargmann, SEATOR environmental laboratory specialist, and Angela Hessenius, SEATOR’s marine ecosystem outreach and research coordinator, to get more details on the current bloom in Silver Bay.
    Last Thursday Bargmann collected algae samples in the bay and turned them over to Hessenius for testing.
    “There wasn’t an abundance of any of the toxin-producing species,” Hessenius reported. “What was blooming was a diatom called leptocylindrus.”
    She added that there also seems to be a bloom of coccolithophore algae.
    “Blooms of coccolithophores tend to produce waters that are this color,” she said.

The Gary Paxton Industrial Park and a milky green Silver Bay are seen from the Blue Lake Road today. (Sentinel Photo by James Poulson)

    Bargmann’s paddleboard sweep for algae on Thursday didn’t pick up any of those particular algae, but both she and Hessenius said that their algae net was not fine enough to reliably capture coccolithophore algae. Neither leptocylindrus nor coccolithophore is toxic.
    Bargmann added that the water turns a brilliant shade of green because the coccolithophore algae have shells made of chalk, which refracts the light. These algae thrive in warm, low-nutrient water, which makes them common later in the summer, Hessenius said.
    While SEATOR does not regularly test shellfish toxicity in Silver Bay, the scientists are confident that the current algae bloom is non-toxic.
    However, they caution, toxic algae blooms remain a real risk in Southeast Alaska. The phytoplankton Alexandrium is especially concerning, as it causes Paralytic Shellfish Poisoning, or PSP.
    Starrigavan Beach is one place that often experiences toxic algae blooms. And while many shellfish will become safe to eat again within weeks of a toxic bloom, Bargmann said, “butter clams have the ability to hold onto PSP for years.”
    If someone is worried that certain shellfish they have collected are toxic, SEATOR can conduct a toxicity test for $50 at their office at 456 Katlian Street. SEATOR also maintains and updates a map on their website, www.seator.org, which provides alerts on harmful algal blooms in the region. If in doubt, either have the shellfish tested or do not eat them.
    Hessenius noted “red tide” is the traditional name for blooms of toxic PSP organisms, but the potentially deadly toxin “can be present in the water in amounts that would cause shellfish to become toxic without having any noticeable change in the water.”
    Symptoms of PSP include numbness in the mouth and difficulty breathing. A person experiencing these symptoms after consuming shellfish should contact emergency services immediately.
    So while the current bloom in Silver Bay is spectacularly beautiful and not harmful, shellfish toxicity remains an important topic in Sitka.
    And that is where SEATOR comes in. Hessenius said that they want “to be there as a resource for people as much as possible, helping people navigate what’s toxic, what’s not toxic, and how to stay safe.”