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Oceanographic changes are occurring more rapidly in recent decades, with new implications for ocean ecosystems and adjacent human communities. It is important to bring attention to these changes while they are unfolding rather than after they have occurred. Here we report on a rapid shift toward colder, fresher water in the deep Gulf of Maine that, as of mid-June 2024, has persisted for at least six months. The shift likely represents an influx of Labrador Slope Water and resembles conditions that predated a major warming shift that occurred in 2011–2012. Deep-water oceanographic conditions in the Gulf of Maine have a strong influence on ecosystem dynamics, including the prey of critically endangered North Atlantic right whales, the seasonal and disease dynamics of American lobster, and the distribution and abundance of kelp forest communities, among others. Oceanographic surprises have an important role in this system, and monitoring how this shift unfolds, oceanographically and ecologically, will give new insights into how oceanographic signals can inform our understanding of ecosystem responses.
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The Surprising Oceanography of the Gulf of Maine
The oceanography of the Gulf of Maine has recently changed in ways that have not been seen previously, but that are likely to be more common in the future. Because of the rapid rate of change, some view the Gulf of Maine as a window into the ocean’s future with the idea that lessons learned can be applied in places that have yet to experience similar rapid changes. Based on a formal statistical definition of oceanographic surprises, the frequency of surprises in the Gulf of Maine is higher and has increased faster than ex- pected even given underlying trends. The analysis suggests that we should expect new kinds of surprises that are characteristically different from previ- ous ones. The implication for policymaking is that in addition to considering long-term environmental changes, it is important to consider scenarios of sudden, unexpected, and potentially extreme environmental changes.
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- Award ID(s):
- 2049308
- PAR ID:
- 10492731
- Publisher / Repository:
- Maine Policy Review
- Date Published:
- Journal Name:
- Maine Policy Review
- Volume:
- 32
- Issue:
- 2
- ISSN:
- 2643-959X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Oceanographic changes are occurring more rapidly in recent decades, with new implications for ocean ecosystems and adjacent human communities. It is important to bring attention to these changes while they are unfolding rather than after they have occurred. Here we report on a rapid shift toward colder, fresher water in the deep Gulf of Maine that, as of mid-June 2024, has persisted for at least six months. The shift likely represents an influx of Labrador Slope Water and resembles conditions that predated a major warming shift that occurred in 2011–2012. Deep-water oceanographic conditions in the Gulf of Maine have a strong influence on ecosystem dynamics, including the prey of critically endangered North Atlantic right whales, the seasonal and disease dynamics of American lobster, and the distribution and abundance of kelp forest communities, among others. Oceanographic surprises have an important role in this system, and monitoring how this shift unfolds, oceanographically and ecologically, will give new insights into how oceanographic signals can inform our understanding of ecosystem responses.more » « less
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Ocean ecosystems are changing, and the climate envelope paradigm predicts a steady shift, approximately poleward, of species ranges. The Gulf of Maine presents a test case of this paradigm, as temperatures have warmed extremely rapidly. Some species have shifted northeastward, matching predictions. Others—namely harmful algal species like Pseudo-nitzschia australis and Karenia mikimotoi—do not appear to have followed climate trajectories, arriving as surprises in the Gulf of Maine. Rare-biosphere dynamics offer one possible ecological lens for understanding and predicting this type of surprise. Rare species in the plankton, possibly more so than southerly ones, may provide management challenges in the future. Improved monitoring and broader coordination of monitoring of the rare biosphere could help develop early warning systems for harmful and toxic algae. A better theoretical understanding of rare biosphere dynamics is also needed. A challenge for the next cohort of ecosystem projections is to predict the newly emerging harmful species of the type that catch us by surprise.more » « less
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The Gulf of Maine (GoM) is currently undergoing rapid environmental and ecological changes and this system is projected to become increasingly stressed in the coming decades. Thus understanding past spatial and temporal conditions of this region is key to understanding how future environmental changes and extreme events may impact fisheries and ecosystem dynamics in the GoM. Changes in the physical and chemical variations in the shells of mollusks can be used as a powerful proxy for studying past climates and environments. In this study, we used the growth and geochemistry signatures in the long-lived marine bivalve Arctica islandica collected from the Down East coastal region in the Gulf of Maine (Jonesport, ME) to evaluate past climatic and hydrographic variability in the northwestern North Atlantic Ocean. The recent collection of shells extends a previously developed master shell growth chronology by 11 years and now spans from 1954 to 2020 CE. Based on visual crossdating techniques, shell growth variability is highly coherent among the population indicating that environmental conditions are driving growth. Variability in annually resolved shell growth increments and stable oxygen isotope values are largely related to sea surface temperatures (SSTs) and water mass properties of the Eastern Maine Coastal Current. This master shell growth chronology and annually-resolved isotope series will fill data gaps prior to instrumental records and allow us to better understand the spatial oceanographic variability in the GoM.more » « less
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Abstract The Gulf of Maine and surrounding western North Atlantic shelf are some of the fastest warming regions of the worlds oceans. The lack of long-term observational records from this area inhibits the ability to assess the timing and initial causes of this warming and consequently accurately predict future changes to this ecologically and economically important region. Here we present oxygen, nitrogen, and radiocarbon isotope data measured in Arctica islandica shells collected in the western North Atlantic to better understand the past temperature and ocean circulation variability of the region over the last 300 years. We combine these results with output from the Community Earth System Model Last Millennium Ensemble simulations to assess the temporal and spatial context of these isotope records. We find that the isotope records capture the end and reversal of a millennium-scale cooling trend in the Gulf of Maine. Last Millennium Ensemble single-forcing simulations indicate that this cooling trend appears to be largely driven by volcanic forcing. The nitrogen and radiocarbon records indicate that ocean circulation is in part driving the reconstructed hydrographic changes, pointing to a potential role of the Atlantic Meridional Overturning Circulation in regulating Gulf of Maine temperatures as suggested by the Last Millennium Ensemble simulations. Both isotope and model results suggest that the Gulf of Maine began to warm in the late 19th century, ultimately driven by increased greenhouse gas forcing. Plain-language Summary The Gulf of Maine, located off of the Eastern Coast of the United States, has experienced significant temperature increases recently. Because the instrumental record only began in 1905, we do not have a good idea of when this warming began and what may have initially caused the warming. Here, we analyze the chemistry of clam shells, which have grown in the Gulf of Maine for hundreds of years, to infer past changes in ocean temperatures and water properties. We combine these results with output from a climate model to reveal that the temperatures reconstructed from the clams shells agree well with the model during the period of overlap. Both the chemical records and the model suggest the Gulf of Maine started warming in the late 1800s as a result of increased atmospheric greenhouse gas concentrations. Before this warming began, the Gulf of Maine region appears to have been cooling. The model suggests that this cooling trend is likely due to the influence of volcanic eruptions. The chemical records from the clam shells also suggest that part of this cooling is likely related to changing ocean circulation patterns.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.53558/JDZI8238
