To help coastal National Parks better prepare for storms and sea level rise, Dr. John King, a University of Rhode Island Graduate School of Oceanography professor, is leading research to map thousands of acres of underwater habitats that have never before been surveyed.
Dr. King introduced Monique LaFrance to habitat mapping eight years ago, when she was an undergraduate summer intern. Now a doctoral student, LaFrance is managing the fieldwork of a habitat-mapping project at Fire Island National Seashore and coordinating research teams at three other coastal National Parks.
Dr. King’s Fire Island team cruises aboard a stark 28-foot pontoon boat. An hour or so before dawn, they set up their gear. Then, for twelve hours straight, they drift through Long Island’s Great South Bay at speeds of five knots or less to collect data.
The sonar technology that Dr. King’s team uses for submerged habitat mapping is called interferometric side-scan sonar. The sonar device releases sound pulses, which bounce back and deliver data that shows the contours of the seafloor.
The research team navigates Great South Bay in straight, slightly overlapping rows, collecting an acoustic image for every square inch of their survey area. In this image, a boat icon indicates their position between gray stripes, which show where the sonar has registered data about geological features and marine life. A black line shows where the team has collected measurements of water depth.
The computer on board the research vessel instantly translates returning sound pulses into visual data that researchers can interpret as distinct geological and biological features. When a sound pulse strikes mud, a low-intensity sound bounces back. A sound pulse striking a boulder returns with high intensity.
The research team finds seafloor-dwelling creatures like worms, shellfish, sand dollars, and amphipods, as well as sea grass beds and geological features like boulder fields, mud flats, sand waves, and sand ripples. The geological features directly impact commercially, recreationally, and ecologically significant species.