Balch-NASA ACE OPCC Meeting; June 6-8 2011 A sharp, step-decrease in the carbon fixation of the Gulf...

Balch-NASA ACE OPCC Meeting; June 6-8 2011

A sharp, step-decrease in the carbon fixation of the Gulf of

Maine...but why?

William BalchBigelow Laboratory for Ocean

SciencesW. Boothbay Harbor, ME

[email protected]


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?


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…)


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)

GNATS cruise track

Embedding GNATS into the changing climatology of New England …

GNATS

Variance in precipitation has increased…

GNATS has seen some of the century’s most extreme precipitation events…

GNATSGardner Maine: 3rd driest year in 100+ years

Gardiner Maine: wettest year in over 100+ years

Of 8 years >1.4m y-1, half during GNATS


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

Summer Solstice

Summer Solstice

Summer Solstice

SPACE

TIM

E

Longitude

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Yarmouth, Nova ScotiaPortland, Maine

70 69 68 67 66Longitude (deg W)

300 200 100 0Dist. from Yarmouth, NS (km)

WMCCExt

EMCC JB SS

70

Note decrease in salinity on west side of Gulf during wet years (in WMCC and Ext EMCC, associated with increased river discharge).

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Top 50m temperature gradient (oC m-1)



WMCCExt

EMCC JB SS

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Note vertical temperature gradient in top 50m decreased in ExtEMCC in 2006-2010 and in SS in ’07&’09

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NO3+NO2 (M)



WMCCExt

EMCC JB SS

70

Note step increase in log DIN after 2007…due to mixing of deeper, nutrient-rich water to surface? Decreased drawdown?

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3

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0.03

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WMCCExt

EMCC JB SS

70

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?

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WMCCExt

EMCC JB SS

70

Note increase in CDOM on west side of Gulf (likely associated with increased river discharge…)

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WMCCExt

EMCC JB SS

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Pmax (mg C m-3 d-1)Note significant step decrease in log maximum primary production after 2007

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300

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30

10

Cmax (mg C m-3 d-1)



WMCCExt

EMCC JB SS

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Note significant step decrease in log calcification after 2007…

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10

3

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0.03

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WMCCExt

EMCC JB SS

70

apg440: a440Note Regions of high ratio don’t make it to JB but nearshore

values reach 15 on both sides of Gulf. High values before 2005

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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?


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


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.


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


Thank you!


Backup slides



WMCCExt

EMCC JB SS

2010

2008

2006

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2002

200070

300

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3.0

Diatom Biomass (g L-1)



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POC-specific growth rate (d-1)Note significant step decrease in POC-specific growth rate after 2007

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2.5

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0.25

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PIC-specific growth rate (d-1)Note, typical values of 0.1 to 0.3 per d; significant step decrease in PIC-specific growth rate after 2008

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1.0

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Balch-NASA ACE OPCC Meeting; June 6-8 2011 A sharp, step-decrease in the carbon fixation of the Gulf...

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Transcript of Balch-NASA ACE OPCC Meeting; June 6-8 2011 A sharp, step-decrease in the carbon fixation of the Gulf...