Synthesis & Modeling Project
Ecosystem structure, biogeochemical fluxes and vulnerability to climate
|PROJECT DESCRIPTION:||This proposal is submitted as part of the U.S. JGOFS
Synthesis and Modeling Project (SMP). We propose to focus our efforts on
the SMP objective of understanding Mechanistic Controls of Local Carbon
Balances, specifically the role of food web structure in controlling particle
flux, particle export, nutrient regeneration and DOC production in oceanic
systems. We will use data generated from the JGOFS process studies to consolidate
field measurements into formal, quantitative descriptions of size and function-based
food web groups and the material flows between them. We will use inverse
techniques to infer unknown (unmeasured) material flows in the food webs.
Finally we will use the trophic networks we derive to test the stability
of the plankton-biogeochemical ecosystem following potential perturbations
to simulate changes due to ocean warming or increased stratification. Scientific
reviews strongly support the assertion that understanding how the biological
pump operates requires detailed knowledge of the relationships between
food web structure, productivity, new production and biological fluxes.
The amount of material leaving the surface layer is usually dependent on
how it is partitioned among the plankton community. In an idealized plankton
community, most of the primary production that passes through bacterioplankton
and microzooplankton is likely to be recycled in the surface layer. In
contrast, a significant portion of the primary production that passes through
the mesozooplankton may become part of the sinking flux of organic matter
via fecal pellet production and active transport below the euphotic zone
due to vertical migration. Although many of the relevant processes were
measured in JGOFS, the resulting data have never been rigorously condensed
in a series of depictions of foodwebs consistent with all the data.
This proposed food web synthesis, a collaborative effort between Hugh Ducklow, George Jackson and Mike Roman, aims to further an ecosystem-based synthesis of JGOFS results. Our goal is the construction or "recovery" of a series of solutions to foodweb networks consistent with observations from the four major US JGOFS Process Studies in the North Atlantic (NABE); the Equatorial Pacific (EQPAC); the Arabian Sea and the Southern Ocean Process Study (AESOPS - Ross). Our project is based on the assumption that improved understanding of ecosystem structure and function depends critically on knowledge of the component rate processes, or intercompartmental exchanges. There now exists a body of formal techniques and theory for analyzing the holistic properties of such flux networks. Our research plan consists of four elements:
|DATA:||- no data submitted -|
|PUBLICATIONS:||Church, M., H. W. Ducklow and D. M. Karl.
2002. Temporal Variability in Dissolved Organic Matter Stocks in the Central
North Pacific Gyre. Limnol. Oceanogr. 47:1-10.
Koeve, W. and H. W. Ducklow. 2002. JGOFS Synthesis and Modeling: The North Atlantic Ocean. Deep-Sea Res. II 48:2141-2154.
Ducklow, H. W., D. K. Steinberg and K. O. Buesseler. 2001. Upper Ocean Carbon Export and the Biological Pump. Oceanography 14:50-58.
Anderson, T. R. and H. W. Ducklow. 2001. Microbial loop carbon cycling in ocean environments studied using a simple steady-state model Aquat. Microb. Ecol. 26:37-49.
Ducklow, H. W. 2001. Bacterioplankton. pp. 217-224 In: Encyclopedia of Ocean Sciences, John Steele, Karl Turekian and Steve Thorpe, Editors. New York: Academic Press.
Ducklow, H. W. 2000. Bacterioplankton production and biomass in the oceans. Chapter 4, pp. 85-120 In: D. Kirchman, Ed., Microbial Ecology of the Oceans. New York: Wiley.
|RELATED PROJECTS:||Ducklow; Fasham; Anderson "Constraining
and understanding bacterial biomass and production variability in ocean
School of Marine Sciences
College of William & Mary
Rte 1208 Greate Rd
Gloucester Point, VA 23062-1346