By Naomi Klouda
Bright red streaks in the waters at Tutka Bay last week caused a bit of a fright among local observers, but the radiant blooming algae pose no reason to be alarmed.
A “red tide” or any unusual discoloration of the water doesn’t always signal paralytic shellfish poisoning, explained George Scanlan, the shellfish permit coordinator for the Alaska Department of Environmental Conservation.
In this case, the red discoloration is from a bloom of algae that aren’t toxic.
“Red is the color given by the organism itself. It becomes more apparent and spectacular when they are present in large concentrations,” Scanlan said.
Ideal warm temperatures and plenty of nutrients in the water can cause the proliferation of the phytoplankton.
Red tides do not always spell a signal for PSP, though scientists warn those who harvest shellfish to be on the safe side and avoid eating shellfish such as clams, mussels and oysters that have not been tested for PSP during these periods. In Kachemak Bay, the toxic chemical is not present in seaweed.
“Oyster growers at Kachemak Bay submit a weekly sample for PSP testing throughout the summer. We have a fairly good record of the level of PSP toxin based on those weekly testings,” Scanlan said. “During this time period of bloom, the samples submitted have been clean. The level of the toxin has been either nondetectable or well below the regulatory limit of 80 micrograms per 100 grams of toxin.”
Catie Busch, the community monitoring program coordinator for the Kachemak Bay Research Lab, said various people reported the waters in Tutka Bay appeared red for certain periods and from certain viewing angles. But when she skiffed through the area several times last week, the red tide wasn’t visible.
“You would need an airplane to fly over it and get an idea. It runs in streaks and comes, and goes,” Bursch said.
Local people tell Bursch this isn’t a new phenomena, but one they have observed seasonally many times. The Kachemak Bay Research Reserve’s program monitoring phytoplankton in the bay is new. Samples near the streaked waters taken for the monitoring program were sent to a NOAA lab in South Carolina for study to find out more about the algae.
About a dozen volunteers help with Bursch’s water monitoring program, but there is none stationed in Sadie Cove or Tutka Bay. Her other monitors have not reported finding red-tidelike waters.
It appears that the toxic algae of the genus Alexandrium is not present in high numbers at Kachemak Bay. “Oysters and mussels feed on these by filtering them, and they accumulate the toxin in their system,” Scanlan said.
A person may suffer from PSP by consuming shellfish that may contain a high amount of the toxin. Symptoms of PSP include a tingling sensation of the extremities, nausea, maybe burning lips, gums, tongue, face, neck, arms, legs and toes. Shortness of breath, dry mouth, a choking feeling, confused or slurred speech, and loss of coordination are also possible. PSP can be fatal.
Kodiak Island has had a long history of high levels of PSP, because there appears to be a higher presence of the genus Alexandrium in the island’s waters.
But as long as DEC has been testing shellfish and water for PSP in Kachemak Bay for well over a decade, the level of toxins suggested by the genus Alexandrium has either not been detected or detected in low amounts, Scanlan said.
“It may be there in small quantities. But we also have to see the specific species,” Scanlan said.
The species Alexandrium fundyense was observed in the sample, but was at numbers below that which are likely to cause harm.
“We’ve had several sightings of water discoloration in years past, but never an outbreak of PSP or people getting sick,” he added.