Cape Cod’s shellfish farmers face many challenges, and one of the biggest is dealing with harmful algal blooms, which can damage shellfish and be poisonous for humans to ingest. But a new project at the Woods Hole Oceanographic Institution is looking at a way to better manage this with the help of a tiny camera.
At Fiddler’s Cove in North Falmouth, aquaculturist Dan Ward is growing bay scallops on a dock moored in the harbor. The scallops are an unsual shellfish for an aquaculturist to grow, because they can be finicky and require very particular conditions to thrive.
While his farm is doing well today, when Ward first started farming bay scallops about seven years ago, he had an issue with the growth of his younger shellfish. He suspected an algae bloom might be to blame.
"We get harmful algae blooms every July and August. And I first noticed it on the farm in 2012," Ward said.
It was a dinoflagellate called Cochlodinium, more commonly known as “Rust Tide,” because it coats everything it touches with a brownish, orange substance. It used to be unusual in places like Fiddler’s Cove, which is why Ward was surprised to see it. But increased water pollution from boats and runoff from houses has helped to foster this new algae growth.
"It kind of causes this orange fuzz, it sticks to everything," Ward said. "And that's kind of a proposed mechanism of harm, sticking to the mantle, to the inside of the shell, to gills, and causing them to suffocate."
These rust tides were unpredictable, and typically when they showed up, Ward couldn’t do anything to save his shellfish, because by the time he could see the harmful algal bloom, it was already too late. It was around this time that he started speaking with Mike Brosnahan, an assistant scientist at the Woods Hole Oceanographic Institution.
Brosnahan reached over the edge of the dock by Ward's scallops and pulled out what looked like a long metal cylinder. His lab has been working to help aquaculture farmers like Ward prevent algae blooms from damaging their crops by using this device, called an Imaging FlowCytobot, to take photos of algae cells. His lab will then analyze the photos in close to real time, and then send Ward an alert if it looks like a bloom is on the way.
"So every 20 minutes or so, it's pulling in about 5 milliliters of water. Then it pushes that water in a very thin stream, and when a cell falls through the stream, the instrument detects it and illuminates it with a flash, and that's how it takes a picture of it," Brosnahan explained. The Cytobot then transmits the photos over an internet connection to a computer at his lab, where he can then analyze what its found.
The Imaging FlowCytobot itself isn’t new - it was invented by WHOI researchers Heidi Sosik and Rob Olsen, and it’s previously been used to monitor water quality in other areas around the Cape. But this is the first time it’s being used to categorize algae to help aquaculturists. Over at Brosnahan’s lab, he showed me photos of the Cochlodinium, the algae that was giving Dan Ward trouble.
"Here's some examples here. They make these chains of cells," he explained, and added that every type of algae had a unique look and structure to it. "They have this really interesting beehive-like structure, and they move quite fast."
Right now, Brosnahan’s lab has to sort through these photos manually and send Ward an email if it looks like a harmful bloom is coming, and then, Ward can take steps to protect his crop. Chatham shellfish warden Renee Gagne recalled a time a few years ago that a harmful algae bloom was detected and a lot of shellfish farms were closed just to be safe.
"It began in Rhode Island and came up through Buzzards Bay and up around Nantucket Sound," Gagne said. "And it was the first time we'd experienced that harmful algae bloom, most areas were closed on a precautionary closure because they didn't really have real-time testing."
And that was frustrating for farmers, many of whom lost money over the closure. This is where real-time testing with alerts could be helpful. In the future, the hope is that the bot will automatically detect when harmful algae appears, and automatically send alerts to nearby shellfish farmers. Ward said those kinds of alerts could mean a lot less closures.
"The more we can collaborate and extend those networks of notifications to other farmers, the more it's going to be impactful financially beyond this location," Ward said.
The hope is that a larger-scale project can be in place in the next few years, with these bots deployed in other areas around the Cape. If implemented, it’s predicted that a system like this could save aquaculturists and wild harvesters hundreds of thousands of dollars in shellfish losses.
