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Marine Ecosystem Responses to Climate-Associated Remote Forcing from the Labrador Sea

Marine Ecosystem Responses to Climate-Associated Remote Forcing from the Labrador Sea. Andrew J. Pershing University of Maine/ Gulf of Maine Research Institute. Charles H. Greene Cornell University. Collaborators. Outline. Project goals Results Future plans. Goals.

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Marine Ecosystem Responses to Climate-Associated Remote Forcing from the Labrador Sea

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  1. Marine Ecosystem Responses to Climate-Associated Remote Forcing from the Labrador Sea Andrew J. Pershing University of Maine/ Gulf of Maine Research Institute Charles H. Greene Cornell University

  2. Collaborators

  3. Outline • Project goals • Results • Future plans

  4. Goals • Characterize interannual variability in physical and biological conditions in GOM/GB • Retrospective approach • Identify drivers of variability • Focus on remote climate forcing • Compare GOM with nearby regions • Scotian Shelf, MAB

  5. Autumn Phytoplankton Small Copepods Herring Gulf of Maine Regime Shift • Hallmarks • Abrupt shift in 1990, reversal in 2001 • Multiple trophic levels • Strongest in autumn

  6. Possible Mechanism Surface Salinity Reduced surface salinity Bigger fall bloom Autumn Phytoplankton Increased copepod reproduction (e.g. Durbin et al. 2003*) *MEPS 254:81-100

  7. Salinity and Fall Stratification • 1D Mixing Model • Salty (1986) and Fresh (1998) initial TS-profiles • 1980-1999 NCEP forcing

  8. Possible Mechanism

  9. Impact of Shift Small Copepods Calanus finmarchicus • Increase in small copepods, including Calanus copepodites • Decrease in adult Calanus

  10. Impact of Shift Small Copepods Calanus finmarchicus Herring Right Whale Calves

  11. Impact of Shift

  12. Herring-Copepod Interactions • Fall-winter: larval herring • Inefficient feeding • Summer: adults • Efficient feeding

  13. Phytoplankton Freshwater

  14. Phytoplankton Freshwater

  15. Fall phytoplankton Haddock recruitment Discussion • Importance of fall-winter period • Spring has dominated research (e.g. GLOBEC) in NW Atlantic • Spring bloom, spawning of cod and haddock • CPR data suggests that there is considerable variability in fall • Fall ecosystem changes can persist throughout the year

  16. 1990s Freshening Salinity Change in the N. Atlantic • Gulf of Maine freshening part of larger pattern extending into Labrador Sea • Non-local processes can influence Gulf of Maine 1990-1994 1995-1999 Figure courtesy of Tim Boyer, NOAA

  17. 1990s Freshening • Freshwater in early 1990s traced to Arctic • NAO+ winds in late 1980s pushed Arctic ice out • Increased outflow through Canadian Archipelago

  18. Future Work • CAFÉ Gulf of Maine Workshop III • Theme: Arctic Influences on NW Atlantic Shelf Ecosystems • November 7-8, GMRI, Portland, ME • Compare Gulf of Maine with Mid-Atlantic Bight • Oleander CPR data set

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