Research informs where and when harmful algal blooms may occur

Julie Matweyou and Jesse Gordon contributed to this story

Harmful algal blooms (HABs) occur when certain species of algae become abundant and produce toxins. Forecasting these blooms could help mitigate human and wildlife health risks. Alexandrium catenella is an alga capable of producing powerful neurotoxins that can accumulate in shellfish and cause Paralytic Shellfish Poisoning (PSP) in humans and wildlife that ingest these shellfish. 

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Alexandrium catenella cyst abundance (cysts/cc) and spatial mapping in Chiniak Bay. Samples collected by UAF KSMSC and cell counts and maps produced by UW Tacoma. Photo courtesy Julie Matweyou.

The patterns of harmful algal blooms over time and across locations are influenced by when and where A. catenella overwinters in the sediment and germinates. There is a need to detect this overwintering stage, called cysts, to be able to forecast spring bloom timing and locations.

Researchers at the University of Alaska Fairbanks are participating in novel research designed to produce more rapid and accurate cyst abundance data. One project, funded through the National Centers for Coastal Ocean Science Monitoring (NCCOS) and Event Response for Harmful Algal Blooms (MERHAB) Research Program, is a multiregional effort that includes partners from University of Washington Tacoma, University of Alaska Fairbanks (UAF), and NOAA National Centers for Coastal Ocean Science (NCCOS) in Beaufort, North Carolina. Sediment and cyst collection are taking place in the Gulf of Maine, Puget Sound, the waters around Kodiak Island, and in Southeast Alaska. The NCCOS lab is developing lab-based methods for cyst enumeration. Two methods are being evaluated—a quantitative polymerase chain reaction assay and a fluorescent in-situ hybridization assay.

Alaska Sea Grant’s Julie Matweyou is leading efforts in Kodiak at the Kodiak Seafood and Marine Science Center (KSMSC) to sample, identify, and enumerate Alexandrium cysts with the goal to map A. catenella cyst concentrations in Chiniak Bay. UAF Fisheries PhD candidate Courtney Hart is leading the Southeast Alaska portion, contributing cyst abundance data and sediment samples.

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Julie Matweyou, onboard the KSMSC research skiff, collects winter sediment in Chiniak Bay using the ponar grab sampler. Photo courtesy Julie Matweyou.

Because A. catenella cysts germinate into the water column in the spring and summer, cysts are collected from December through February, while they are dormant and resting in the sediment. Matweyou is collecting cysts using a device called a ponar grab sampler, which is dropped from a boat and used to pull up sediment. Matweyou has completed three winter collection seasons (2019, 2020 and 2021). 

A local intern, funded by Sea Grant’s Community Engaged Internship, helped process 2019 and 2020 samples last summer, and opportunities for student involvement will continue with the ongoing work.

Alaska Sea Grant director, Ginny Eckert, noted that harmful algal bloom research is important to coastal communities throughout Alaska, including the Gulf of Alaska, because of the importance of shellfish farming and shellfish harvesting. “This cyst research will help inform future forecasts and to better understand spatial and temporal variability in blooms, with the ultimate goal to protect human health” she said.