Ferries as Ships of Opportunities in Plankton Research

A shipboard view of a ferry in Nantucket Sound

WHOI biologist Scott Gallager mounted sensors on ferries to chronicle conditions in Nantucket Sound. Data collected by the sensors shows that on a flood tide, when water flows into the Sound from the west, salinity is higher and chlorophyll lower, while the situation reverses on an ebb tide, when water flows the other way. Photo credit: Tom Kleindinst, WHOI

The islands of Nantucket and Martha's Vineyard, lying off the coast of Cape Cod, are well-known tourist destinations: their summer populations can soar to five and ten times winter levels. Residents and tourists alike travel there and back across the same body of water, Nantucket Sound. As they make the crossing to and from the ports of Woods Hole or Hyannis, most travelers have little understanding of what's happening in the water beneath them. But to Woods Hole Oceanographic Institution (WHOI) biologist and zooplankton ecologist Scott Gallager, gaining a clear picture of the complex physical, chemical, and biological factors operating in Nantucket Sound waters is critical. And he has forged an unusual partnership to help him get it.

With Woods Hole Sea Grant support, Gallager and his WHOI colleagues have teamed up with The Steamship Authority, a provider of ferry service to the islands, to install instrumentation on two of its ferries. The goal is to collect high-resolution data about the Sound that will help scientists better understand the coastal Atlantic Ocean, its food webs, and its future. While the idea is not unique—ferries have been used to collect data throughout the world for over a decade—it has appeal (merit).

Instrumentation on the ferry transects…will allow us to have a complete description of the incoming and outgoing plankton communities in surface waters," says WHOI biologist Scott Gallager.

WHOI zooplankton ecologist checks water samples in his laboratory.

WHOI zooplankton ecologist Scott Gallager, in his laboratory, checking water samples. Photo credit: Tom Kleindinst, WHOI.

A map showing the location of Nantucket Sound, the triangular section of ocean between Cape Cod and the islands

Nantucket Sound is the triangular section of ocean between Cape Cod and the islands, with Nantucket at the apex and Martha's Vineyard along one side. It's a busy place, with all types of craft making the crossing, from pleasure and fishing boats to shipping freighters and oil tankers. Source: www.insidecapecod.com

Gallager is interested in the smallest animals in the ocean—zooplankton—and the water conditions that affect how they live and grow. "Seasonal changes in plankton diversity," says Gallager, "are a reflection of nutrient input, light, and temperature, coupled with biological processes including predator–prey interactions, growth, and reproduction." Zooplankton depend on plant plankton (phytoplankton), which depends on light, nutrients, and seasons. Gallager feels that if we learn enough about how zooplankton will respond to changing climate conditions and inputs such as contaminants and nitrogen loading, we may be able to predict what can happen to our fish stocks.

Enter the ferries—"ships of opportunity," says Gallager—outfitted with sensors to measure water temperature, salinity, and pressure, water clarity, oxygen, and digital images of the plankton. The ferry Katama collects data on the Woods Hole-to-Martha's Vineyard run; the ferry Eagle does the same between Hyannis and Nantucket. Together, these vessels are helping to paint a portrait of Nantucket Sound over time. The data travel over a wireless connection to shore where Gallager makes them available in real time to scientists and the public on the project web site, http://sealion.whoi.edu/ferries.

Already, an interesting picture is forming of the western side of the triangle: Gallager can match chlorophyll amounts—a measure of how much phytoplankton is in the water—with tidal flow and the salinity of the water. "We have known that the phytoplankton is patchy," he says, but it will be neat to follow the diagram over time across the Sound, and see that it's patchy, and why."

Gallager would like to create a regional model—one that allows "now- and fore-casts of environmental perturbations, providing an understanding of what affects plankton diversity in light of coming climate change." He invites the public to visit the website and come along for the ride.

For more information about this Woods Hole Sea Grant-supported project, contact Dr. Scott Gallager, 508-289-2783, sgallager@whoi.edu

Ferries as Ships of Opportunities in Plankton Research:

Woods Hole Sea Grant Support Seeks to Improve Understanding of Plankton Diversity in the Coastal Ocean