June 27, 2017 — We know Clint Eastwood was the High Plains Drifter. And we’ve heard Bob Dylan’s tale of the Drifter’s Escape. But now the Northeast Fisheries Science Center in Woods Hole is employing drifters not on the plains but on the waves around Cape Cod and the Gulf of Maine.
“I’m excited about our latest drifter project,” proclaimed NMFS Oceanographer Jim Manning. “It’s one of many we’ve had and it seems like a real application for drifters. We’ve used them for a lot of fun educational purposes but our recent project in the Bay of Fundy has real purpose.”
They’ve been used with purpose in Cape Cod Bay as well. But, you might ask, what exactly is a drifter? It’s not a shiftless character begging at the kitchen door for scraps.
“It looks like an underwater kite, like a box kite,” Manning explained. “It’s a meter by a meter of cloth sails and they only thing that sticks out is a satellite transmitter. It provides us an estimate of the surface current.”
Its function is similar to that of a glass bottle with a note in it. You toss it in the ocean, it drifts somewhere, and you find out where it went.
With the old bottle you had to wait months or years until someone wrote back but a transmitter can tell you where it is today. It reveals where the surface currents are headed and can tell you where anything drifting along, like a cold-stunned sea turtle in Cape Cod Bay, or a swath of toxic algae in Maine, might wind up.
The current project Manning is excited about focuses on Alexandrium fundyense, the plankton that causes paralytic shellfish poisoning in anyone that eats a shellfish, usually a clam, that has filter fed on it. It’s the same algae that lives in the Nauset Marsh between Orleans and Eastham, and causes annual shutdowns of shellfishing harvests.
The plankton has a resting stage where it sits as cysts in the mud. When conditions are right and the water warms the cysts germinate, it swims up towards the surface and the currents carry it away. In Nauset Marsh it doesn’t go far and stays in the marsh but in the Bay of Fundy it’s carried down the coast.
“The main objective is to help numerical modelers try to simulate the ocean,” Manning said. “A couple of universities have big computer models. These models are used for a variety of things. We’ve deployed the drifters north of Grand Manan Island up in the Bay of Fundy to demonstrate how complicated the currents are. Every time we put one out it goes in a different direction.”