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Vital Gulf phytoplankton survey resumes

A new agreement between NOAA’s Northeast Fisheries Science Center, the Marine Biological Association in Plymouth, England and the Woods Hole Oceanographic Institution, announced in October, will allow a long-running plankton survey in the Gulf of Maine to resume. The survey was originally conducted across the Gulf of Maine from 1961 to 2017. 

In this satellite image from the Woods Hole Oceanographic Institute, the densities of phytoplankton in the Gulf of Maine can be seen as variations of grey. WHOI image.

“Continuing a long-term time series like the Continuous Plankton Recorder Survey is essential to understanding the impact of climate change to marine ecosystems,” said Chris Melrose, a research oceanographer at the Northeast Fisheries Science Center’s laboratory in Narragansett, Rhode Island and NOAA representative on the agreement.   “Many marine species are shifting their distributions as ocean waters warm. Because plankton are an important food source for many species, including the endangered North Atlantic right whale, knowing about changes in the plankton helps us to understand other changes we see in the ecosystem.” The National Marine Fisheries Service (NMFS) will provide funding for the survey through the NOAA Cooperative Institute for the North Atlantic Region, hosted by the Woods Hole Oceanographic Institution. The Marine Biological Association in England manages merchant vessel-based plankton surveys around the world. The association will run and maintain the resumed Gulf of Maine survey through 2024 under this agreement. The survey uses a continuous plankton recorder (CPR), a sampling device that is about 3 feet long. In this survey, it is towed from so-called “ships of opportunity,” such as merchant vessels. These vessels ply the same routes between ports from year to year. Scientists refer to the routes as survey transects. The recorder stays at a depth of roughly 33 feet. It filters and collects plankton from the water over long distances. The plankton samples are stored on silk mesh in a cartridge inside the instrument and are analyzed later in a laboratory. Methods of sampling and plankton analysis have not changed since 1958, resulting in an important baseline of data against which change can be measured. “The value of sampling in an area accumulates each subsequent year, building a dataset of evidence and insight that we can use to understand recent changes in the marine ecosystem of the Gulf of Maine,” said David Johns, head of the CPR Survey at the Marine Biological Association. In 1961, cooperating commercial vessels began towing CPRs in the Gulf of Maine during their routine transits between ports. NOAA’s Northeast Fisheries Science Center assisted with those efforts, and in 1974 inherited the route between Boston, Massachusetts and Halifax, Nova Scotia. The center began a second route in 1971 across the Mid-Atlantic Bight between New York and New Jersey and Bermuda. Between 1961 and May 2013, there were 446 successful CPR tows on commercial vessels along the Gulf of Maine transect. At the time, the CPR survey in the Northwest Atlantic was the second longest running CPR program, after the original in England. It was also the longest running plankton time-series in the Northwest Atlantic.  The Fisheries Science Center discontinued the two transects in 2013, but the CPR Survey in England picked up the routes and continued sampling in the Northwest Atlantic until 2017. Data from the CPR tows surveys in the Gulf of Maine have been analyzed by the Gulf of Maine Research Institute, a partner in the NOAA Cooperative Institute for the North Atlantic Region.  “The Gulf of Maine is changing quickly and the CPR is our best tool for seeing the impact on the base of the food web,” said Andy Pershing, former chief scientific officer at the Gulf of Maine Research Institute. “This view is essential for understanding how climate change will impact commercial species like cod, herring and haddock, and protected species like right whales.”

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