A low-cost towed video camera system for underwater surveys: comparative performance with standard methodology

TROBBIANI, GASTÓN A.; ALEJO J. IRIGOYEN; LEONARDO A. VENERUS; FIORDA PEDRO; ANA M. PARMA

ENVIRONMENTAL MONITORING AND ASSESSMENT

SPRINGER

Lugar: Berlin; Año: 2018 vol. 190

0167-6369

Technological advances in the field of underwatervideo have led to an exponential increase in theuse of drifting cameras (DC) and remotely operatedvehicles (ROVs) to monitor the diversity, abundance,and size structure of marine life. Main advantages ofDCs relative to ROVs are their lower costs and the muchsimpler logistics required to operate them. This studycompares the performance of a new low-cost DC systemequipped with a novel measuring device with that of astandard DC bearing an array of laser pointers. The newDC, which can be operated from a small boat, carries apair of parallel steel Bwhiskers^ that are dragged on theseabed within the field of view of the camera, providinga scale for measuring and estimating the density ofbenthic biota. An experiment conducted using an arrayof objects of known sizes laid on the bottom showed thatits performance in terms of both size and density estimationwas similar to that of the standard techniquebased on laser pointers. Measurement errors had a negligiblenegative bias (− 2.3%) and a standard deviationthat ranged between 13 and 8% for objects from 25 to110 mm in size. The whiskers offered a simplified method for density estimation that avoids the need to calculate the width of the field of view, thus reducing the video processing time by around 60%with respect to thestandard method. Briefly, the new system offers anefficient low-cost alternative for benthic ecology studiesconducted on soft or non-irregular bottoms.