An essential lower link of Earth’s food chain, plankton are the diet of choice for sperm whales, whale sharks, fishes, fish larvae, anemones—big plankton even feed on little plankton, and zooplankton feed on phytoplankton. These tiny marine organisms baffle researchers on several fronts. It is unclear why they concentrate in particular areas, or why they suddenly appear and disappear. Some species are toxic to fishes and humans. In the phenomenon known as the “red tides,” plankton cluster in vast clouds, consume all the food in the area, and then disappear, and researchers have no good explanation for why these creatures appear to simply eat themselves out of existence. Some plankton luminesce in response to shear, causing problems for the Navy, since this luminescence effectively announces the presence of a submarine to anyone in the vicinity or to satellites.

Professor Joe Katz is studying plankton with Dr. Edith Widder, a world expert in bioluminescence from the Harbor Branch Oceanographic Institute, and postdoctoral researcher Dr. Ed Mekiel. In a diving expedition off the Gulf of Maine, they collected data on plankton with a submersible holographic camera that records in situ holograms of sample volumes of ocean water. When reconstructed, these holograms create a 3D image of the original sample volume that can be examined in the laboratory. They scan the volume with a microscope to a resolution of 3–10 microns, revealing a three-dimensional picture of the various species of plankton and their distribution in space. These multi-exposure holograms are used for measuring the flow and reveal a story of the plankton’s behavior over time, providing a unique window on the interaction between plankton species and the conditions under which they tend to gather or to luminesce.

[Welcome & Overview] [People] [Research] [Seminars, Events & Positions] [Undergraduate Programs] [Graduate Programs] [Student Groups] [Campus Life] [Home]