Harmful algal bloom monitoring gets underway

High swell was rocking the R/V Sikuliaq in the Port of Nome on June 13. The research vessel has a lot of state-of-the-art features, but the group of Nomeites who boarded the ship that afternoon made a beeline for an inconspicuous black tank securely strapped to a lab bench. This $140,000 instrument was an Imaging FlowCytobot, or IFCB for short.
Summer has a new distinction in the Bering Strait region: it’s harmful algal bloom season. An IFCB aboard another research vessel, the Norseman II, helped scientists detect last year’s highly toxic bloom of the single-celled species Alexandrium catenella. That discovery prompted unprecedented warnings about consuming marine harvests across the region. Now this year, environmental monitors are on the lookout for another event. They’re patching together resources to boost surveillance in the short term, and thinking about how instruments like an IFCB could fit into long-term monitoring strategies.
The R/V Sikuliaq is a familiar sight in the Port of Nome. The ice-breaking research vessel is owned by the National Science Foundation and operated by the University of Alaska Fairbanks. Each year the ship brings several groups of scientists on competitive and meticulously planned research cruises through Alaskan waters. This year, while the vessel is out at sea for various missions that have nothing to do with algae, it will be collecting water that could signal whether a bloom is occurring.
Mrun Pathare, a research assistant with the Woods Hole Oceanographic Institution, or WHOI, in Massachusetts, explained to the group touring the ship how the IFCB works. Essentially, water samples get sent through narrow tubes that filter out any particles larger than 150 microns. The water passes through a microscope that automatically takes images when a cell is detected. Researchers train algorithms to categorize different cells. It’s much faster work than a human could do with a water sample and a microscope.
“All the cells go in one single straight line past the cell detector,” said Pathare. “The laser goes off, the camera goes off, and you’re getting a lot of information about each particle that passes through. Each and every thing that is in that sample of water is being catalogued by the computer.”
Pathare manages eight different IFCBs, mostly at sites along the East Coast. The bots can be placed underwater at aquaculture farms or on research platforms or sit aboard ships. The data they produce can be monitored remotely; Pathare plans to spend most of her summer back in Massachusetts. But the machines are sometimes finicky and require special knowledge to fix them or unclog the filters—a task Pathare had to complete in Nome.
Emma Pate, the training coordinator and environmental planner in the Office of Environmental Health at Norton Sound Health Corporation, was part of the delegation getting a closer look at the IFCB. It was her first time seeing one in person.
The Alaska Ocean Observing System, or AOOS for short, recently acquired an IFCB but has not given any indication yet about where it intends to deploy the instrument. In the event that the organization does decide to send the device to the Bering Strait region, Pate wants to be prepared. She is discussing a potential partnership with NSEDC, envisioning that one of their vessels that’s regularly crossing the region’s waterways could host an IFCB.
“It would give consistent sampling throughout our offshore water in areas where I can't reach and in areas where there's marine mammal wildlife,” Pate said.
For now, she and Alaska Sea Grant agent Gay Sheffield are continuing their more analog coastal sampling program. They are visiting villages around the Bering Strait region to answer questions about harmful algal blooms and to train tribal environmental coordinators to take their own water samples by hand and analyze them under a microscope. Pate and Sheffield are also taking samples off Cape Nome, although that’s more challenging this year after Typhoon Merbok changed the shape of the coastline.
“We can’t get our sample bottle and net three meters underwater vertically because it's all shallow now,” Pate said. “The rock around Cape Nome fell into the area where we normally would put that sample bottom bottle down.”
Having access to an IFCB wouldn’t be a silver bullet. Pathare noted the limitations of the instrument.
“It is important to note that the IFCB really only has the capacity to show the cell count and sometimes a high cell count does not indicate presence of toxins,” she said.
It turned out that last year’s bloom included both high cell counts and high levels of toxins. But further lab testing was required to understand just how toxic the bloom was. Pate said that she and Sheffield will accept samples—and pay for shipping—of subsistence foods that people might be afraid to eat in the event of a suspected bloom. High levels of saxitoxins produced by Alexandrium blooms can cause paralytic shellfish poisoning, which could be deadly.
“The health of the water is very important,” Pate said. “We have a lot of our subsistence resources coming from that water. With climate change and other factors, it's projected that we will continue to see these harmful algal blooms in our water. It's important for us to keep moving forward and establishing a good foundation for this program to be long term.”