Locating macrophytes from the sky or underwater, what support for managers?

Abstract

The study of the distribution of macrophytes is essential, whether for knowledge or management purposes. Historically dependent only on field surveys, the acquisition of these data can now rely on new methods based on remote sensing. Whether optical (use of satellite or airborne radiometric measurements) or acoustics (use of sonars or on-board radars), remote sensing can now provide effective technical solutions and provide relevant information through the development of original processing methods. It allows the identification of plant covers and their nature (differentiation of species or types of floating meadows). The data is geolocated precisely through the use of GPS or image geo-referencing systems, thus limiting observer bias. In addition, the instruments used provide access to information for sites that are difficult to access (e.g. wetlands, private land, great depth) and thus limit the human needs and time required. Finally, the development of processing chains makes it possible to have methods that are spatially and temporally reproducible, making the use of these technologies very relevant for, e.g., the monitoring and understanding of colonization processes. The interest of remote sensing for mapping and helping to manage macrophytes is real, but still underutilized.