AUVs Map Coral Reef Environment
January 2008: a team of scientists, engineers, and technical divers have been mapping the coral reefs around the Caribbean island of Bonaire using Autonomous Underwater Vehicles (AUVs). Support for one of the AUV mission teams has been provided by Tom Hiller and James Baxter of GeoAcoustics, running a compact GeoSwath wide swath bathymetric sonar mounted on a Gavia AUV.
The Bonaire mission has been funded by the US National Oceanic and Atmospheric Administration (NOAA). Part of NOAA's mission is to explore the ocean for the purpose of Discovery and the advancement of knowledge. The Bonaire mission aims to enhance knowledge of coral reefs and their value, and to motivate people to take action to sustain them. The work in Bonaire has an especially high profile in 2008, which is the International Year of the Reef (see www.IYOR.org).
The Bonaire expedition is being led by Mark Patterson of the Virginia Institute of Marine Science (VIMS), along with co-Principal Investigators Arthur Trembanis (University of Delaware), Jim Leichter and Dale Stokes (Scripps Institution of Oceanography). Dr. Trembanis has recently placed an order for a GeoSwath-equipped Gavia for the Coastal Sediments, Hydrodynamics, and Engineering Laboratory (CSHEL) in the College of Marine and Earth Studies at the University of Delaware. As well as the Principal Investigators (and 16 students from Delaware), academics have come to assist the mission from NOAA's Undersea Research Center (NURC, USA), the University of British Columbia (Canada), and the National Oceanography Centre Southampton (UK). Technology specialists from Iceland and England are also on-hand, helping gather the data needed to understand the reef environment.
One of the key aims of the mission is to look at ways of collecting sub-sea data using novel technology. Three AUVs are mapping the corals and taking measurements from the sea around them. Two ‘Gavia' man-portable AUVs along with the ‘Fetch1' AUV designed by Mark Patterson, are carrying various types of survey equipment into areas that would be dangerous to visit or slow to explore using divers or surface boats.
One of the Gavia AUVs deployed in Bonaire carries a GeoSwath Plus sonar. The GeoSwath is a wide-swath mapping system which will bring back detailed charts of the depth and acoustic properties of the seafloor around the island. The GeoSwath can completely map several square kilometers in a morning's work. Data has been collected from shoreline missions and down to the 200m depth contour.
The AUV application of the compact GeoSwath is a new development. More typically you would find a GeoSwath sonar mounted on a small survey boat. The GeoSwath Plus data has contributed to the inclusion of many more reefs within the Habitat Protection zones, and the mapping program is continuing over the next two years to help in the understanding of the biodiversity associated with shallow sub tidal reefs in coastal waters.
