Budgets of Biogenic Elements in the NW Atlantic Ocean Margin: Synthesis and Modeling
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Budgets of Biogenic Elements in the NW Atlantic Ocean Margin: Synthesis and Modeling |
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Sponsoring Agency: National Science Foundation OCE-98-18804 (as subcontract through Skidaway Institute of Oceanography) |
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Principal Investigators: Donald G. Redalje and Steven E. Lohrenz |
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INTRODUCTION |
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Project Overview |
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To reduce major uncertainties in predicting future global environmental quality, it is imperative to understand the sources and sinks of atmospheric CO2, the role of anthropogenic activities in disrupting the natural carbon cycle, and the effects of, and feedbacks between, these activities and the natural carbon cycle. Within the oceans, the ocean margin carbon cycle will be the most impacted. The U.S. Department of Energy designed and implemented a field study called the Ocean Margins Program (OMP) to examine carbon cycling in the continental margin of the western North Atlantic Ocean. The central objectives of the OMP are (1) to quantify the processes and mechanisms that affect the cycling, flux, and storage of carbon and other biogenic elements at the land/ocean interface; (2) to define ocean-margin sources and sinks in global biogeochemical cycles; and (3) to determine whether ocean margins, including continental shelves, are quantitatively significant in removing carbon dioxide from the atmosphere and isolating it via burial in sediments or by export to the interior ocean, or elsewhere. |
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This field program resulted in the most extensive, multidisciplinary set of water column and seabed observations ever obtained over an ocean margin. However, the DOE has terminated its marine research programs prior to the planned synthesis of the OMP. In the absence of an integrated, funded, and organized data analysis, this $50M investment in ocean margin carbon fluxes would have been lost. Fortunately, a first level analysis of this extensive dataset has been funded through the JGOFS Synthesis and Modeling effort to begin to address the role of the ocean margins and rivers. In this program, we intend to complete the original OMP objectives and facilitate the incorporation of the resulting database into the analyses of the various complementary JGOFS programs. The OMP dataset specifically addresses all of the major SMP goals, complements the JGOFS oceanic databases, and thus is highly relevant to SMP programmatic goals. |
| Water Column Process Studies | |
| There were two process cruises during the formal field year in 1996: one took place during near the time of the surface water temperature minimum (March), and the other took place during the strongly stratified summer period (July). There was a strong link between the goals of these cruises and the purposes of the moored array. The intent of the process cruises was to provide a link between the highly detailed and complete set of measurements possible from a ship to the less encompassing data set provided by the moored array. Additionally, the ship-based measurements provided a means to calibrate and quantify those data obtained from the moored instruments. Together, the plan was to obtain a temporal and spatial picture of the flow of the various water masses passing through the area and biological transformations that occurred within those waters. The first was a regional scale survey consisting of three cross-isobath transects (Fig. 1) and 36 stations between 35.5oN and 36.7oN covering the north-south extent of the moored array; the end transects also coincided with the main cross-isobath moored arrays. | |
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Figure 1. Surface map of primary production in gC m2 d-1 showing an area of high primary production at the shelf break during March 1996. This map was determined using P-E measurements and vertical profiles of irradiance and chlorophyll. |
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The second segment of the cruises concentrated on the control
volume sub-array, located over the outer shelf just south of the northern
transect. The location of the
array was chosen to be hydrographically the simplest, minimizing
complications from the Chesapeake Bay outflow on one hand, and Gulf Stream
intrusions on the other. The
inner portion of the subarray consisted of six moorings within a 10 km box
which were heavily instrumented and included much of the biological
sensors. The concept behind
this portion of the cruises was to understand the similarities and
differences between the seasonal biological processes which are inherently
Lagrangian in nature, and the Eulerian measurements that the moorings
would provide. Thus, the plan
was to follow pairs of Lagrangian drifters as they passed through the
subarray while periodically making Eulerian type measurements at the fixed
location of the central mooring. Despite
the inherent unpredictability of outer shelf currents, the plan worked
just as intended on both occasions: the drifters were released just north
of the array, and corkscrewed their way through the array generally
following the local isobaths. The
deployments lasted 71 hours with 24 stations during the winter cruise and
92 hours with 37 stations during the summer cruise.
Because of the strong seasonal stratification, the attendant
vertical shear and the separate biological regimes above and below the
thermocline, the summer period presents the more complex system to
diagnose. |
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The biological and physical measurements made on both cruises
included the standard hydrographic parameters of temperature, salinity,
dissolved oxygen, transmission and fluorescence from the surface to within
one meter of the bottom. These
samples were analyzed for a wide range of parameters including: nutrients
from frozen samples (NO2, NO3, SiO4, and PO4), dissolved oxygen, DOC,
TCO2, alkalinity, chlorophyll, phaeophytin, photosynthetic parameters via
an FRR fluorometer, POC/PON, bacterial activity, biomass of all major
photo- and heterotrophic plankton groups, and HPLC phytoplankton pigments.
In addition, depth-resolved meso-zooplankton tows were obtained at
most stations. At selected
stations, profiles of photosynthetically available radiation (PAR) and
spectral downwelling irradiance and upwelling radiance (14 channel
Satlantic Profiling Radiometer) were obtained as well as profiles of
spectral absorption and attenuation using a WET Labs AC-9.
At selected stations we examined total particulate and dissolved
absorption characteristics using the quantitative filter pad technique (Kishino
et al., 1985). Productivity,
photoautotrophic C biomass and C specific growth rate measurements (Redalje, 1993) derived from either simulated in situ on deck incubations
or from photosynthesis-irradiance (P vs. E) photosynthetron studies were
also made each day at selected stations along the transects and from each
of the drifter locations. Underway
measurements included temperature and salinity, chlorophyll, PCO2, and
currents from an ADCP. Dilution
experiments to measure growth of phytoplankton and grazing by nano/microzooplankton
were conducted every day. Bacterial
production and grazing by nano/microzooplankton were determined daily by
digestive enzyme assays and also using fluorescently labelled prey. Shipboard incubations to determine predation on
microzooplankton by mesozooplankton were conducted at near-daily
intervals. Molecular studies
were also conducted aboard ship to determine
mechanisms of regulation of ribulose bisphosphate carboxylase (RubisCo)
in natural phytoplankton communities, and the influence of physical mixing
processes on bacterial composition and growth rates. |
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Numerous other PIs were involved in these process studies.
They included: D. Chipman (LDEO), M. Dagg (LUMCON), P. Falkowski
(Rutgers), C. Flagg (BNL), S. Giovannoni (OSU), P. Kemp (SUNY), Z. Kolber
(Rutgers), J. LaRoche (BNL), S. Lohrenz (USM), Paffenhofer (SkIO), Palenik
(UCSD), Paul (USF), D. Redalje (USM), L. Shapiro (UO), B. and E. Sherr (OSU),
R. Tabita (OSU), P. Verity (SkIO), D. Wallace (BNL), and C. Wirick (BNL). |
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PRODUCTS
Publications
Lohrenz, S. E., A. D. Weidemann, and M. Tuel (2003) "Phytoplankton spectral absorption as influenced by community size structure and pigment composition," Journal of Plankton Research, 22:639-657.
Lohrenz,
Steven E., Donald G. Redalje, Peter G. Verity, Charles L. Flagg and Kenneth
V. Matulewski, (2002) "Primary production on the continental shelf off Cape
Hatteras, North Carolina," Deep-Sea Research II, 49, 4479-4509.
Donald G.
Redalje, Steven E. Lohrenz, Peter G. Verity, and Charles L. Flagg, (2002)
“Phytoplankton dynamics within a discrete water mass off Cape Hatteras, North
Carolina: The Lagrangian experiment,” Deep-Sea Research II, 49,
4511-4531.
Verity, Peter G., Redalje, D. G., Steven E. Lohrenz, and G. A. Paffenhofer, (2002) “Coupling between primary production and pelagic consumption in temperate ocean margin pelagic ecosystems,” Deep-Sea Research II, 49, 4553-4569.
Lochhead, V. C., Steven E. Lohrenz, D. G. Redalje, and A. D. Weidemann (1999) Optical properties and their relationship to pigment concentrations in continental shelf waters off Cape Hatteras, North Carolina, EOS, Transactions, American Geophysical Union, 80, OS121. (abstract)
Carroll, C. L., Steven E. Lohrenz (1998) Size-fractionated pigment distributions in the Chesapeake Bay Outflow Area, EOS, Transactions, American Geophysical Union, 79, OS109. (abstract)
Lohrenz, S. E., D. G. Redalje, K. M. Matulewski and P. G. Verity (1998) Phytoplankton size distributions and pigment-specific absorption in coastal waters off Cape Hatteras, NC. EOS, Transactions, American Geophysical Union, 79, OS183. (abstract)
Lochhead, V. C., Steven E. Lohrenz and D. G. Redalje (1998) Spectral reflectance ratios and their relationship to chlorophyll concentrations in continental shelf waters off Cape Hatteras, NC, EOS, Transactions, American Geophysical Union, 79, OS109. (abstract)
Lochhead, V. C., Steven E. Lohrenz, and D. G. Redalje (1998) Spectral reflectance ratios and their relationship to chlorophyll concentrations off Cape Hatteras, NC, Journal of the Mississippi Academy of Sciences, 43, 60.
Matulewski, K. V., Redalje, D. G. and Steven E. Lohrenz (1998) Assessment of variability in spectral measurements of inherent optical properties in Case II waters off of Cape Hatteras, North Carolina, EOS, Transactions, American Geophysical Union, 79, OS183. (abstract)
Matulewski, K. V., Redalje, D. G. and Steven E. Lohrenz (1998) Variability in the inherent optical properties in spring and summer case II water masses off Cape Hatteras, North Carolina, Journal of the Mississippi Academy of Sciences, 43, 60.
Redalje, D. G., Steven E. Lohrenz, and K. V. Matulewski (1998) Primary production within discrete water masses off of Cape Hatteras, North Carolina: A comparison of two productivity models with bottle incubations, EOS, Transactions, American Geophysical Union, 79, OS183. (abstract)
Presentations
Lohrenz, S. E., D. G. Redalje and P. G. Verity (2001) Seasonal contrasts in biomass and primary production over the continental shelf off Cape Hatteras, North Carolina. American Society of Limnology and Oceanography, 12-16 February, 2001, Albuquerque, New Mexico. [abstract]
Redalje, D. G., Steven E. Lohrenz, P. G. Verity and K. Holtermann (2001) Phytoplankton community structure within a discrete water mass in the coastal waters off Cape Hatteras, North Carolina. American Society of Limnology and Oceanography, February 12-16, 2001, Albuquerque, NM. [abstract]
Verity, P. G., Redalje, D. G., Steven E. Lohrenz, and G. A. Paffenhofer (2001) Coupling between primary production and pelagic consumption in temperate ocean margin pelagic ecosystems. American Society of Limnology and Oceanography, February 12-16, 2001, Albuquerque, NM. [abstract]
Lochhead, V. C., Steven E. Lohrenz, D. G. Redalje, and A. D. Weidemann (1999) Optical properties and their relationship to pigment concentrations in continental shelf waters off Cape Hatteras, North Carolina, American Geophysical Union/American Society of Limnology and Oceanography Ocean Sciences Meeting, January 24-28, San Antonio, TX.
Lochhead, V. C., Steven E. Lohrenz and D. G. Redalje, Spectral reflectance ratios and their relationship to chlorophyll concentrations in continental shelf waters off Cape Hatteras, NC, American Geophysical Union/American Society of Limnology and Oceanography, 9-13 February, San Diego, CA (1998).
Lohrenz, Steven E., D. G. Redalje, K. M. Matulewski and P. G. Verity, Phytoplankton size distributions and pigment-specific absorption in coastal waters off Cape Hatteras, NC, American Geophysical Union/American Society of Limnology and Oceanography, 9-13 February, San Diego, CA (1998).
Matulewski, K. V., Redalje, D. G. and S. E. Lohrenz, Assessment of variability in spectral measurements of inherent optical properties in Case II waters off of Cape Hatteras, North Carolina, American Geophysical Union/American Society of Limnology and Oceanography, 9-13 February, San Diego, CA (1998).
Redalje, D. G., S. E. Lohrenz, and K. V. Matulewski, Primary production within discrete water masses off of Cape Hatteras, North Carolina: A comparison of two productivity models with bottle incubations, American Geophysical Union/American Society of Limnology and Oceanography, 9-13 February, San Diego, CA (1998).
Related Links:
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