OPTICAL SENSING IN MULTIMODAL MARINE MONITORING

This study presents the design and implementation of an autonomous, open-source, low-cost (<450€), and low-power optical sensor developed to complement acoustic studies, particularly in the context of monitoring NBHF (Narrow-Band High-Frequency) species using instruments deployed off the Chilean coast. Beyond cetaceans, the system also provides valuable applications for fish monitoring, enabling visual assessment of species presence, abundance, and behavior. The system enables continuous image capture over periods ranging from 4 to 8 days.The prototype, called UWOS (UnderWater Optical Sensor), is built from readily available components and can be synchronized with the Qualilife HighBlue (QHB, developed by the SMIoT laboratory at the University of Toulon) passive acoustic recorder. It integrates a wide-angle camera within a watertight housing, offering a 120° field of view per unit. Laboratory tests characterized optical distortions, power consumption, and waterproofing reliability. Field deployments were then carried out in Toulon (France) and off Concepción (Chile), demonstrating autonomous operation under real conditions and the ability to interact reliably with the QHB system.The combination of UWOS and QHB, named COPEPOP (Coordinando Opto-acústica para el Estudio de Peces en el Océano Pacífico), was successfully deployed at Isla Chañaral, providing complementary visual data to acoustic monitoring. This simple, reproducible, and cost-effective system offers a promising complementary tool for extending the temporal and spatial scope of underwater observations, with potential applications in scientific research, education, and citizen science.