Researchers Say Climate Change Caused Ecosystem Shift in Atlantic
Contact: Ben Slayton (207) 228-1638; David Munson (207) 581-3777
PORTLAND, Maine — In a paper published in a recent issue of the journal Science, Andrew Pershing, of the UMaine School of Marine Sciences and the Gulf of Maine Research Institute, and Charles Greene, of Cornell University’s Ocean Resources and Ecosystems Program, state that significant changes in the marine ecosystems of the Northwest Atlantic are the result of a significant increase in meltwater entering the ocean due to climate change.
Pershing and Greene suggest that the increase in low-salinity water entering the Atlantic from the Arctic altered circulation and stratification patterns, resulting in what they refer to as an ecosystem regime shift: a large, relatively rapid alteration in the ecosystem at multiple levels. The shift was marked by significant changes in the abundances and seasonal cycles of phytoplankton, zooplankton, and fish populations.
“Around 1990, the abundance of small copepods–rice grain sized crustaceans that are food for small fish–increased a hundred fold”, said Andrew J. Pershing, Ph.D., Ecosystems Modeler at the Gulf of Maine Research Institute and Professor at UMaine School of Marine Sciences. “Our work suggests that the increase in copepods was caused by an increase in the amount of freshwater entering the Gulf of Maine. When saltier conditions returned around 2001, the changes we saw reversed.”
Dramatic changes in the abundance of herring, shrimp and other species in the 1990s have been attributed by some to the reduction in predation by cod and other large fish following the collapse of groundfish populations in the 1980s. Pershing and Greene suggest that a bottom-up change in the populations of a variety of North Atlantic species would have occurred with or without the collapse of cod, due primarily to significant changes in climate.
“Climate scientists are predicting that the North Atlantic will get fresher, due to more precipitation and ice melt. While we can’t say that conditions in the 1990s were caused by global warming, our work suggests a new way that global warming could impact marine ecosystems.”
Pershing, who received his Ph.D. in ecology from Cornell in 2001, is a leader in the use of computing technology to model and visualize how the ocean environment influences fish and mammal populations over time and to predict potential future population changes.
Pershing is a faculty member at the UMaine School of Marine Sciences, which is based in Orono and has a statewide teaching, research, and outreach presence. He is stationed at the Gulf of Maine Research Institute’s laboratory on Portland’s working waterfront, as part of a unique partnership between the two institutions. At GMRI, he serves on an interdisciplinary research team, which has expertise in fishery ecology, oceanography, ecosystem modeling, fishing gear technology, and resource economics. This research team works collaboratively with the fishing community and other marine stakeholders to undertake strategic research initiatives in the Gulf of Maine.
About the UMaine School of Marine Sciences
Formed 10 years ago, the School of Marine Sciences offers undergraduate and graduate degree programs in the marine sciences, conducts research worldwide on all aspects of the oceans, with particular emphasis placed on interdisciplinary problems. The School aims to develop specific scientific understanding of the marine environment that is Maine’s heritage, to integrate and communicate that knowledge through educational programs and to apply it toward stewardship of sustainable marine resources. The school is comprised of some 55 faculty members from various academic disciplines, and has facilities in Orono, Walpole and Franklin, Me.
About Gulf of Maine Research Institute
The Gulf of Maine Research Institute (GMRI) was established in 1968 to develop pragmatic solutions to complex problems to support the evolution of the Gulf of Maine ecosystem and the human community that depends on it. GMRI accomplishes this by convening the public to discuss, debate and resolve aquatic resource conflicts, conducting unbiased scientific research to improve public understanding of the Gulf of Maine and its watershed, and educating Maine residents and visitors about fresh and saltwater ecosystems.
GMRI’s hybrid marine research and education facility, located on the Portland waterfront, provides a neutral, collaborative platform for research partnerships among leading research organizations, the fishing community, and private industry with a focus on fishery ecosystem research. GMRI is closely linked to the community, strategically focused on the Gulf of Maine bioregion, and complements its research programs with a unique education program that engages Maine’s middle school students with marine science.