UVC-Based Biofouling Suppression for Long-Term Deployment of Underwater Cameras

Spatially distributed underwater sensor systems are important tools to understand long-term trends in marine ecosystems. For example, in the ongoing UFOTriNet project, noninvasive techniques for the purpose of monitoring fish populations are investigated. A challenge within this and related projects is the long-term operation of cameras in brackish and fully saline water. The impact of biofouling, especially on the underwater cameras, should be minimized for reliable imaging. In the context of the UFOTriNet project, for this purpose, an energy-efficient and environmentally friendly antifouling concept based on UVC irradiation was developed and investigated to extend operation times and to reduce energy and maintenance costs. Innovative contributions include LED-based UVC irradiation from the inside of the camera's pressure housing into the water column, periodic UVC irradiation intervals that are significantly shorter than those commonly reported, and an analysis and comparison of the irradiance for internal and external irradiation configurations. The concept was confirmed by a measurement campaign in the Kiel Fjord, located in the southwest Baltic Sea.