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A sharp, step-decrease in the carbon fixation of the Gulf of Maine...but why?

A sharp, step-decrease in the carbon fixation of the Gulf of Maine...but why?. William Balch Bigelow Laboratory for Ocean Sciences W. Boothbay Harbor, ME bbalch@bigelow.org. Science Questions behind this talk….

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A sharp, step-decrease in the carbon fixation of the Gulf of Maine...but why?

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  1. A sharp, step-decrease in the carbon fixation of the Gulf of Maine...but why? William Balch Bigelow Laboratory for Ocean Sciences W. Boothbay Harbor, ME bbalch@bigelow.org Balch-NASA ACE OPCC Meeting; June 6-8 2011

  2. Science Questions behind this talk… • SQ-1: What are the standing stocks, composition, & productivity of ocean ecosystems?  How and why are they changing?  • SQ-2: How and why are ocean biogeochemical cycles changing?  How do they influence the Earth system?  • SQ-3: What are the material exchanges between land & ocean?  How do they influence coastal ecosystems, biogeochemistry & habitats?  How are they changing?  • SQ-5: How do physical ocean processes affect ocean ecosystems & biogeochemistry?  How do ocean biological processes influence ocean physics?  • SQ-6: What is the distribution of algal blooms and their relation to harmful algal and eutrophication events?  How are these events changing?  Balch-NASA ACE OPCC Meeting; June 6-8 2011

  3. Addressing these questions requires both remote sensing and in-water measurements…GNATS-Gulf of Maine North Atlantic Time Series • 12+ year transect time series across Gulf of Maine (35 years if you include historical data on same line) • Sample design is to use flexible schedule vessels (ferries, small research vessels) that can specifically target clear-sky days for concurrent satellite and ship measurements. • Due to this sampling model, GNATS has provided 19.7% of all chlorophyll matchups & 13.3% of radiance match-ups in SeaBASS for MODIS Aqua plus SeaWiFS (not including Terra or MERIS…) Balch-NASA ACE OPCC Meeting; June 6-8 2011

  4. Intensive GNATS Program (1998-2010; 12+ years) -What are we sampling? • Hydrography (SST, Salinity; XBTs, MVP profiles of T,S, chlorophyll fluorescence to 100m) • Chemistry (NO3+NO2, PO4, SiO2) • Biogeochemistry (POC, PIC, DOC, Biogenic Si) • Biology (chlorophyll a, phaeopigments, 14C primary production & calcification, phytoplankton enumeration- coccolithophorids, Flow-CAM functional groups • Bio-Optical measurements • Inherent optical properties [spectral absorption (total and dissolved), scattering, backscattering, acid-labile backscattering, volume scattering function • Apparent optical properties [above-water spectral upwelling radiance, sky radiance, downwelling irradiance] • Seasonal Slocum glider missions along the GNATS transect (T, S, CDOM fluor, Chl Fluor, bbp531nm,AOPs at 7 wavelengths) Balch-NASA ACE OPCC Meeting; June 6-8 2011

  5. GNATS cruise track

  6. GNATS Embedding GNATS into the changing climatology of New England …

  7. Variance in precipitation has increased…

  8. Gardiner Maine: wettest year in over 100+ years p p p p p p p p GNATS Of 8 years >1.4m y-1, half during GNATS Gardner Maine: 3rd driest year in 100+ years GNATS has seen some of the century’s most extreme precipitation events…

  9. Summer Solstice TIME Year Summer Solstice Summer Solstice SPACE Longitude Yarmouth, Nova Scotia Portland, Maine Our transect between Portland and Yarmouth is roughly east-west. 1998-2006- temporal bias to late spring to early fall. Year-round effective 2007; Use the Hovmoller space-time diagrams Balch-NASA ACE OPCC Meeting; June 6-8 2011

  10. Note decrease in salinity on west side of Gulf during wet years (in WMCC and Ext EMCC, associated with increased river discharge). 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Year round sampling

  11. Note vertical temperature gradient in top 50m decreased in ExtEMCC in 2006-2010 and in SS in ’07&’09 Top 50m temperature gradient (oC m-1) 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Year round sampling

  12. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Note step increase in log DIN after 2007…due to mixing of deeper, nutrient-rich water to surface? Decreased drawdown? Ext EMCC SS WMCC JB NO3+NO2 (mM) 3 Year round sampling 1 0.3 0.1 0.03

  13. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Note step increase in in the Si(OH)4:DIN in 2007 & 2008 across the GOM; river supplied silicate? Vertical mixing of deeper silicate-rich water? Ext EMCC SS WMCC JB Year round sampling

  14. Note increase in CDOM on west side of Gulf (likely associated with increased river discharge…) 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Year round sampling

  15. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Note significant step decrease in log maximum primary production after 2007 Pmax (mg C m-3 d-1) 300 Year round sampling 100 30 10

  16. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Note significant step decrease in log calcification after 2007… Cmax (mg C m-3 d-1) 10 Year round sampling 3 1 0.3 0.1 0.03

  17. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Note Regions of high ratio don’t make it to JB but nearshore values reach 15 on both sides of Gulf. High values before 2005 apg440: af440 Year round sampling

  18. So what is causing these changes? • Clearly, vertical mixing has changed in upper 50m • Clearly, surface nutrients have gone up • POC & PIC-specific growth rates have decreased, hence decreased nutrient draw down • Extraordinary amounts of freshwater injected into the GOM • Increased grazing? We’ve always pre-filtered samples through 250um Nitex mesh to remove large grazers. • Some inhibitory substance introduced? CDOM? Chelators with river-born sediments? Xenobiotic? Balch-NASA ACE OPCC Meeting; June 6-8 2011

  19. Future Activities • GNATS funding ran out December 2010 but we are working to re-establish funding, especially to a) capture ongoing ecosystem changes plus b) continue calibration/validation of MODIS and soon-to-launch VIIRS in optically complex coastal waters • Paper- Space/time and anomaly analysis • Paper- Decadel variations in particle types and size • Paper- Glider-based analysis of carbon production Balch-NASA ACE OPCC Meeting; June 6-8 2011

  20. Conclusions • New England has undergone major changes in climatology over the last century (mainly warming and increased variance in precipitation…the latter showing extreme levels in the last decade) • Over the decadal scale of GNATS, such changes have resulted in increased river input into the Gulf of Maine with associated colored dissolved organic matter injections well away from the coast • The GoM has seen a step change in a wide variety of variables (hydrographic, nutrient chemistry, optical, biological) associated with the record-breaking precipitation year (2005). Cause and effect? • Future predictions of ecosystem variability associated with climate change are complex and can be counterintuitive, particularly due to interactive effects of variables. This makes a strong case for coordinated, multiplatform measurements in order to better predict ecosystem impacts. Balch-NASA ACE OPCC Meeting; June 6-8 2011

  21. Acknowledgements • D. T. Drapeau, B. C. Bowler, E. S. Booth, J. Goes, E. Lyczskowski, D. Alley, Laura Lubelczyk (Bigelow Laboratory), L. A. Windecker (U.C. Santa Barbara), E. Olson (WHOI), A. Ashe (U.Maine) + 70 others (occasional trips) for 148 crossings covering >44,000 km (the circumference of Earth) and 427 person days at sea over 12+ years. • Staff and crew of the M/S Scotia Prince, F/V Ella & Sadie, R/V Argo Maine, R/V Connecticut and high-speed ferry, “The CAT” • NASA for funding Balch-NASA ACE OPCC Meeting; June 6-8 2011

  22. Thank you! Balch-NASA ACE OPCC Meeting; June 6-8 2011

  23. Backup slides Balch-NASA ACE OPCC Meeting; June 6-8 2011

  24. Diatom Biomass (mg L-1) 2010 2008 2006 2004 2002 2000 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB 300 100 30 10 3.0

  25. 2.5 1.6 1.0 0.6 0.4 0.25 0.16 0.1 0.06 0.04 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Note significant step decrease in POC-specific growth rate after 2007 POC-specific growth rate (d-1) Year round sampling

  26. 70 70 69 68 67 66 Longitude (deg W) 300 200 100 0 Dist. from Yarmouth, NS (km) Ext EMCC SS WMCC JB Note, typical values of 0.1 to 0.3 per d; significant step decrease in PIC-specific growth rate after 2008 PIC-specific growth rate (d-1) 10 3.0 Year round sampling 1.0 0.3 0.1 0.03 0.01 0.003 0.001

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