University of California, San Diego

Approximately one third of the oxygen we breathe is generated through the photosynthesis of marine organisms discovered only in the last 30 years.  These organisms form the base of all marine food webs and are important in regulating the planet’s climate, yet almost everything known about them comes from bulk samples or laboratory experiments.  Their small size presents challenges that have made direct observation in the ocean using existing technology difficult, if not impossible.  A team at UCSD proposes to build the world’s first high resolution, 3D, in situ, underwater microscope.  The microscope will be configured with an inner imaging volume with high spatial resolution nested inside a larger, lower-resolution imaging volume.  Image analysis of data from the high-resolution inner volume will permit identification of marine nanoplankton, while analyses of the larger, outer volume will permit subsequent tracking and behavioral observations.  The microscope will also simultaneously image fluorescence to enable discrimination between zooplankton and different kinds of phytoplankton that are important in global carbon cycling.  The new device and its subsequent use will allow seeing, for the first time, the most abundant organisms on the planet in situ and how they interact with each other.