Colleen Durkin

Moss Landing Marine Labs

Resolving the biology of sinking particles and cells

Micrograph images of cells and sinking particles collected in sediment traps. Credit: Colleen Durkin.

Wednesday, March 9, 2016
Pacific Forum—11:00 a.m.

Carbon is naturally sequestered in the deep ocean by organic particles
and organisms that sink out of the surface ocean in a process called “the biological
pump”. The amount of carbon that is transported by this process is difficult
to constrain due, in part, to the complex ecological interactions that control the
composition of particles and the magnitude and the efficiency of export. Laboratory
growth experiments can resolve the environmental conditions that affect
sinking speed of individual phytoplankton cells (diatoms in this study), but how
important are small and relatively slowly sinking particles in exporting carbon
from the surface ocean? Do individual phytoplankton cells make a difference?
To identify the particles responsible for carbon export out of the surface ocean, a
variety of sediment traps were deployed in the upper mesopelagic depths of the
Sargasso Sea, across a large region of the South Atlantic Ocean, and at the Rhode
Island shelf break. Resolving the particles responsible for carbon export through
image analysis helps identify the important mechanisms that lead to the transport
of phytoplankton-derived carbon out of the surface ocean. In the future,
combining image analysis with molecular-based analyses of particles collected
in sediment traps and remotely sensing optical instruments will help to improve
estimates of carbon uptake by the biological pump.

Print version (PDF)

Next: May 4, Chuck Wilson


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