Decadal-Scale Variability in the Surface Flow of the Gulf of Maine Coastal Current: The Impact of Changing Climate Conditions on Coastal Circulation

The Gulf of Maine (GOM) is one of the most productive and ecologically important marine environments on the planet. The Gulf of Maine Coastal Current (GMCC), which stretches along the western side of the GOM from the Bay of Fundy to Cape Cod, plays an important role in supporting this productivity by transporting nutrients, larvae and dinoflagellates southwestward along the Canadian and New England coastlines. Climate change has led to alterations in GOM ecosystems in recent years: GOM water temperatures have warmed and distributions of marine species have shifted. However, the impacts of the changing climate on the circulation within the GOM, including the path and velocity of the GMCC, have remained unclear. Here, we examine data collected by satellite tracked surface drifters and velocity data collected by the NERACOOS buoy array in order to investigate inter-decadal changes to the flow of the GMCC. We find that over inter-decadal timescales, the alongshore surface flow of the GMCC has slowed, particularly in the region southwest of Penobscot Bay. The slowdown observed in the GMCC surface flow is most likely attributed to a local strengthening of the southwesterly winds over the time period of interest. The Gulf of Maine (GOM) is the region of the ocean stretching between the Bay of Fundy and Cape Cod. The GOM is well known as a productive fishery and an important habitat for endangered species. The biological productivity of the GOM relies on the transport of things like nutrients and larvae throughout the region. In the western GOM, much of this transport is carried out by the Gulf of Maine Coastal Current (GMCC), which stretches from the Bay of Fundy to Cape Cod. Unfortunately, climate change is impacting the GOM: record breaking temperatures and changes in the distribution of species have been observed in recent years. In this study, we use data collected from surface drifters and anchored buoys to investigate whether the waters of the GMCC are changing as the temperatures warm. The results of this study indicate that the surface flow of the GMCC has slowed, particularly in the region southwest of Penobscot Bay. This slowdown is likely due to an increase in the strength of the local winds from the southwest, which may have disrupted the southwestward flow of the surface waters. Surface velocities in the Gulf of Maine Coastal Current have slowed on inter-decadal timescales, particularly southwest of Penobscot Bay An intensification of the southwesterly component of the winds in the region likely contributed to the observed changes