Microscale distributions of phytoplankton: Peeping into the planktonic bedroom

Peter Franks, Ph.D.
Scripps Institution of Oceanography

Wednesday, September 17, 2003
Pacific Forum – 3:00 p.m.

It has long been recognized that microscale (<1 m) patches of plankton must exist and play an important role in the dynamics of the planktonic ecosystem. However, observing and quantifying the scales of patchiness has always been limited by technology. Peter Franks and colleague Jules Jaffe have designed and built a free-falling imaging fluorometer system for observing the microscale distributions of phytoplankton. By using a thin sheet of laser light, phytoplankton fluorescence can be stimulated and then imaged with a sensitive CCD camera.  With the 300 micron resolution, individual phytoplankton cells can be identified. In vertical profiles of images, cell counts can be performed with centimeter vertical resolution over 90 m depths, and thin (10 cm thick) layered structures have been observed throughout the water column. This instrument is giving an exciting new view into the spatial and temporal structures of the planktonic community.

Next: Seasonal dynamics of phytoplankton and zooplankton biomass off Monterey Bay, California