What’s behind the toxic algae producing killer shellfish in Alaska?  

Anushka Rajagopalan working with a lab sample
05/16/23 – BOSTON, MA. – Anushka Rajagopalan conducts research on toxic Alaskan algal blooms that cause paralytic shellfish poisoning, which threatens marine life and even humans, for her co-op at the Woods Hole Oceanographic Institution on Tuesday, May 16, 2023. Photo by Photo by Alyssa Stone/Northeastern University

Most people probably associate algal blooms with red tides in Florida that can lead to skin irritation, burning eyes and rashes in exposed individuals.

But, increasingly, Alaska’s Bering Strait also is home to toxic algal blooms—blooms that threaten the shellfish industry and cause paralytic shellfish poisoning that imperils the lives of seals, birds, fish, foraging pets and even humans.

Northeastern University co-op student Anushka Rajagopalan is part of a team of researchers in Don Anderson’s lab at the Woods Hole Oceanographic Institution in Massachusetts who are studying the conditions behind the creation of Alaska’s harmful algae blooms.

In particular, Rajagopalan is focused on Alexandrium catenella, a single-celled marine plankton that produces the neurotoxins that cause paralytic shellfish poisoning.

“It’s impacted the Alaskan coastal community pretty severely,” says Rajagopalan, whose six-month co-op ends June 30.

“Indigenous communities are particularly impacted by it because shellfish and fish are main sources of subsistence,” Rajagopalan says.

Poisoning occurs after shellfish ingest the neurotoxin created by algal blooms.

“The shellfish themselves don’t get poisoned,” Rajagopalan says.

But paralytic shellfish poisoning “can cause symptoms in birds, fish, and marine mammals that are similar to humans,” according to the University of Alaska, which says “those animals are affected by consuming zooplankton, shellfish, and or forage fish that have the toxic algae in their systems.”

Pets foraging on beaches can be impacted, as well as humans who eat the infected shellfish.

The most recent human death associated with paralytic shellfish poisoning in Alaska was in 2020.

The Washington state Department of Health says deaths have occurred 30 minutes after ingesting poisoned shellfish, with fatalities attributed to suffocation as chest muscles become paralyzed. There is no antidote to the poisoning, only life support for severe cases.

“Research that is done in this lab will be helpful for future mitigation strategies and long term monitoring for coastal communities,” says Rajagopalan, a third-year student majoring in ecology and evolutionary biology.

The co-op student says she is finalizing analysis of water and sediment samples containing Alexandrium cells collected by a WHOI research vessel from a stretch of sea from western Alaska to the eastern border of Russia. 

Each tube of water comes with information about the temperature, salinity, nutrient content and other environmental factors in its collection area, Rajagopalan says.

She examines the Alexandrium cells under a microscope using fluorescent probes, a protocol known as the FISH method for Fluorescence in Situ Hybridization.

“They collected samples not only at the surface of the water but at various depths throughout the water,” Rajagopalan says. 

“We’re wondering whether these Alexandrium blooms differ based on water depth and how that could relate to other environmental factors such as physical oceanographical and biogeochemical factors.” 

A 2021 report from the National Oceanic and Atmospheric Administration Fisheries says that algal blooms were once rare in Alaska but are increasing, which scientists from NOAA and WHOI say is due in at least part to warming seas. 

The Anderson lab at WHOI hopes to publish the results of the research she is working on by next year, says Rajagopalan, who plans to finish up her undergraduate degree at Northeastern by 2024.

She says she intends to pursue a Ph.D. in fields relating to biodiversity and conservation biology, perhaps coral biology—which she studied in her first co-op last year at the Smithsonian Tropical Research Institute in Panama.

In the meantime, Rajagopalan is counting on research being done at Anderson’s WHOI lab to make a difference when it comes to combating the effects of algal blooms.

“There are whole communities around the world that are relying on this research and information,” she says.

“Awareness about these projects will hopefully bring more support and funding for long-term monitoring.”

Cynthia McCormick Hibbert is a Northeastern Global News reporter. Email her at c.hibbert@northeastern.edu or contact her on Twitter @HibbertCynthia.