Provides information about complexity of watersheds. Outlines ways to form partnerships, to develop strategies for enhancing watershed resources, and to implement enhancement projects.
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, Extension forest engineering specialist, Corvallis
Linda J. Brewer, graduate student in crop and soil
The Critical Depth Hypothesis formalized by Sverdrup in 1953 posits that
vernal phytoplankton blooms occur when surface mixing shoals to a depth shallower than a
critical depth horizon defining the point where phytoplankton growth exceeds losses. This
hypothesis has since served as a cornerstone in plankton ecology and reflects the...
The ¹⁴C-uptake method is the most common approach employed for estimating primary production in the ocean. Normalizing ¹⁴C-uptake to chlorophyll a and time yields a value termed the assimilation number, which is thought to reflect phytoplankton physiology. It is often assumed that the measured rate of ¹⁴C-uptake is between net...
The measurement of phytoplankton carbon (C[subscript]phyto) in the field has been a long-sought but elusive goal in oceanography. Proxy measurements of C[subscript]phyto have been employed in the past, but are subject to many confounding influences that undermine their accuracy. Here we report the first directly measured C[subscript]phyto values from the...
Satellite measurements allow global assessments of phytoplankton concentrations and, from observed temporal changes in biomass, direct access to net biomass accumulation rates (r). For the subarctic Atlantic basin, analysis of annual cycles in r reveals that initiation of the annual blooming phase does not occur in spring after stratification surpasses...
High-latitude phytoplankton blooms support productive fisheries and play an important role in oceanic uptake of atmospheric carbon dioxide. In the subarctic North Atlantic Ocean, blooms are a recurrent feature each year, while in the eastern subarctic Pacific only small changes in chlorophyll (Chl) are seen over the annual cycle. Here...
Provides information about complexity of watersheds. Outlines ways to form partnerships, to develop strategies for enhancing watershed resources, and to implement enhancement projects.
The export of organic carbon from the surface ocean by sinking particles is an important, yet
highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the
global ocean carbon export using satellite observations, including determinations of net primary production
and the slope of the...
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and food-web models
Siegel, D. A., K. O. Buesseler, S. C. Doney, S. F. Sailley, M. J. Behrenfeld, and
The export of organic carbon from the surface ocean by sinking particles is an important, yet
highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the
global ocean carbon export using satellite observations, including determinations of net primary production
and the slope of the...