Despite all of the elbow room the open ocean offers miniscule life forms such as phytoplankton, bacteria, and viruses, these creatures sometimes converge into patches called “thin layers.” The centimeter- to meter-thick layers have densities as great as 1,000 times that of the water around them and can have profound effects on the way light and sound move through the water. Yet little is known about them. That’s why they are the latest oceanographic mystery being investigated by the Office of Naval Research.
A 5-year, $9 million project dubbed LOCO, for “Layered Organization in the Coastal Ocean,” is bringing together researchers from several universities and research institutions to answer the most basic questions about thin layers. Among them: Why, where, when, and how do they form and dissipate? Does the layering differ between nearshore and offshore environments? What are the biological and optical properties of the layers? Can we create models to predict their occurrence?
The researchers are employing a number of technologies in Monterey Bay, California, through September 10, 2005. They’ll rely on boats, planes, divers, and even autonomous underwater vehicles (AUVs) because despite being found around the globe, thin layers are easy to overlook because they are so, well, thin.
According Dr. James Eckman, program officer in the Ocean Optics and Biology division of the Ocean, Atmosphere, and Space S&T Department, “A floating profiler, which consists of sensors spaced along a vertical cable, could easily miss them because a sensor could be just above or below a layer and never notice it’s there. Only a slow profiling instrument that moves up and down through the water column has been able to detect them.” LOCO scientists will be working to categorize water chemistry, biology, and physics, and to determine the spatial extent of thin layers.
One of the AUVs that will swim through the water and thin layers in Monterey is REMUS, developed by Hydroid, Inc., with support from ONR. Lidar (similar to radar but based on light scattering), bioacoustical instruments, and straight water sampling will also contribute to our understanding of thin layers.
LOCO brings together researchers from the Naval Air Warfare Center Aircraft Division Patuxent River, Md. (NAVAIR), University of California at Berkeley and at Santa Cruz, University of Hawaii, University of Massachusetts Dartmouth, University of Rhode Island, the Monterey Bay Aquarium Research Institute, Oregon State University, Woods Hole Oceanographic Institution, and BAE Systems.