Remote Sensing of Kelp (Laminariales, Ochrophyta): Monitoring Tools and Implications for Wild Harvesting

Kelps (Laminariales, Ochrophyta) are ecologically and commercially important habitat-forming brown macroalgae, found in coastal ecosystems worldwide. Their presence in the sublittoral fringe makes monitoring kelp forests problematic and consequently they remain relatively understudied. Remote sensing offers new avenues to monitor difficult-to-access biomes, particularly kelp habitats, but previous monitoring efforts have only been tested on an ad hoc basis and a standardized protocol for monitoring kelp requires development. In view of on-going and emerging threats to kelp, there is a need for monitoring to establish detailed baseline information. Wild harvesting of kelp is increasing, illustrated by growing numbers of seaweed and seaweed-containing products. Simultaneously, climate change is causing sea-surface temperatures to rise and influencing kelp distribution and abundance globally. This study reviews the potential for remote sensing in macroalgal studies, with an emphasis on kelp and provides a conceptual framework to support the development of standardized monitoring protocols. Satellite-born sensors and aerial photography have been effective, but these distant sensors cannot operate effectively in turbid temperate waters, and many image surveys do not account for changing tides. Advances are being made in acoustic monitoring, particularly multibeam sound navigation and ranging (SONAR). With some development, there is great potential for a standardized monitoring protocol for kelp, aiding management and conservation efforts.