The adventure goes on …
Mutibeam sonars, like side-scan sonars, use swath technology. However, unlike side-scan sonars, multibeam sonars produce better depth (bathymetry) data than backscatter data. Although backscatter is also recorded, the imagery acquired is generally of a lower quality than that recorded from side-scan sonars.
Sidescan sonars use a swath of sound to esonify the seafloor. They differ from single-beam sounders in that they have a much larger footprint shape.
A single-beam sounder calculates the depth below the ship using the time it takes a sound pulse to travel to the seafloor, reflect, and then return back to the transducer.
Current studies were performed using a 0.4 MHz Nortek Aquadopp acoustic Doppler current profiler (ADCP). The ADCP was mounted in a downwards-looking orientation on a retractable ADCP boom attached to the side of the research vessel. The retractable ADCP boom-mount used by Ocean Ecology was a highly modified adaptation of the concept presented by Hench et al. (2000) (“A portable retractable ADCP boom-mount for small boats“).
The Skeena River originates high in the coastal mountains of northwestern British Columbia, at the edge of the Spatsizi Plateau, and flows 610 km to reach the Pacific Ocean. Draining a total area of 54,400 km2, the Skeena is the second largest river in the province, and one of the longest un-dammed rivers in the world.
Eelgrass beds are both ecologically valuable and potentially threatened. They fall within the “critical” category of DFO’s habitat rating system, and DFO has concluded that eelgrass has characteristics which meet the criteria of an Ecologically Significant Species. The United Nations recently estimated a 15% loss in seagrass habitat globally over the last decade.