The copepod, Calanus finmarchicus, is a dominant member of the plankton in the Gulf of Maine, (GoM), despite its location at the southern edge of the species\u27 subarctic range. Wilkinson Basin, one of the three deep basins in the GoM, harbors very high concentrations of the early developmental stages of C. finmarchicus in the summer through winter and serves as a source of C. finmarchicus to GoM coastal ledges and banks. A recent study based on C. finmarchicus habitat characteristics across the North Atlantic predicts that climate-driven change will force the distribution of C. finmarchicus northward out of the GoM over the next several decades. However, the oceanographic and life history responses of C. finmarchicus to environmental variability in the Gulf are complex and largely unknown. The research in this RAPID proposal takes advantage of a rare opportunity to test a hypothesis about the control of C. finmarchicus abundance in the GoM from climate change related external forcing. The hypothesis states that a distinctly lower C. finmarchicus abundance follows, with a two-year lag, the occurrence of a very negative North Atlantic Oscillation (NAO). The specific processes that causally connect low C. finmarchicus with the NAO are not known. The research here tests the prediction that C. finmarchicus abundance will be very low in Wilkinson Basin in 2012, two years after one of the most negative NAOs on record, dating back to the 1860?s. Field observations in the form of a time series of measurements of hydrography, food availability and C. finmarchicus stage abundance will be taken at a fixed station in Wilkinson Basin and in the Maine coastal region, supported by measurements taken on the Scotian Shelf. A research survey, coordinated with a scheduled cruise in the Gulf of Maine in September, 2012, will take additional collections in Wilkinson Basin and throughout the GoM. Frozen and ethanol preserved samples of C. finmarchicus will also be collected for population genetic studies. The abundance results will be compared with historical time series and survey data collected over the past two decades, confirming or refuting the expectation of extreme NAO influence on GoM C. finmarchicus populations. The lipid-rich early developmental stages of C. finmarchicus represent a particularly important energy source for planktivorous fish such as herring, mackerel and sand lance, supporting coastal fisheries as well as the summer resident populations of the endangered North Atlantic right whale, which feeds on C. finmarchicus directly. This RAPID research provides information needed to understand sources of variability in C. finmarchicus supply to the GoM ecosystem and the data will be used to support the development of coupled physical-biological models of responses of the C. finmarchicus population to the NAO and other sources of external forcing. Archived samples will be used for genetic analyses addressing research questions about shelf-basin connectivity developed by the ocean sciences community in the U.S. BASIN Implementation Plan. The project contributes to the implementation of the observing subsystem for the Northeast Association for Coastal Ocean Observing Systems (NERACOOS), which has identified the need for observing change in zooplankton diversity as part of its regional build-out planning. It will also contribute to development of the story of C. finmarchicus as an asset for teaching marine science to K-12 students, through COSEE curriculum resources and the Cohen Center for Interactive Learning at the Gulf of Maine Research Institute
