The Driftcam: A buoyancy controlled pelagic camera trap

The midwater column of the ocean has been largely unexplored by man. These are regions below the sun-lit upper ocean and above the seafloor. According to the Monterrey Aquarium 2004 Annual Report the midwater column contains the largest communities of species in the world. Despite this, very little is known about the biodiversity in this region of the water column [1]. Little imagery of these species in their natural environment exists. An autonomous, deep-submergence, buoyancy-compensated `Driftcam´ has been developed to probe the mesopelagic and bathypelagic regions of the water column. The system utilizes an HD video camera and a 7200 lm LED lighting system inside a polished borosilicate spherical pressure housing. An embedded computer controls the camera and lighting. An electrically driven, hydraulic buoyancy engine has been developed to facilitate depth control through the water column. The buoyancy engine utilizes an encoder-less, stepper-motor driven, hydraulic piston to pump inert oil to and from an external bladder. A pressure transducer provides depth feedback to an embedded, intelligent motor drive. The Driftcam is designed for a controlled operating depth of up to 1500 m and a recoverable depth of 6000 m. Surface recovery is facilitated by a light beacon, a VHF beacon, and an ARGOS satellite transmitter capable of functioning for 1 year. In addition, the system is highly portable, measuring 1.5 m in total length. To date, the system has been deployed over 8 times to depths beyond 100 meters.