Lake-wide mapping of littoral habitat using underwater videography

Abstract

Littoral zones − referring to benthic areas above the light compensation depth − provide numerous ecosystem functions, including mediating light, temperature, and nutrient dynamics, and supporting important foraging and refuge areas for macroinvertebrates, fishes and water birds. Habitat assessments of littoral zones remain fundamental to lake and fisheries management, however traditional field surveys are time-intensive and limited in their spatial extent, whereas desktop evaluations using remote sensing and aerial imagery are cost prohibitive and require considerable data processing expertise. In light of these challenges, this study demonstrated the ability to use simple, cost-effective underwater videography to conduct lake-wide spatially-continuous assessments of littoral habitat. For lakes across a gradient of shoreline and riparian development in northwestern United States, we map the areal coverage of macrophytes, coarse woody habitat, bottom substrates, and artificial structures in littoral zones. Underwater videography represents a relevant tool for environmental monitoring because it allows for the estimation of littoral habitats at fine spatial grains across broad spatial extents. Data can also be obtained rapidly and at relatively low cost, providing a permanent record of habitat conditions that can used to monitor trends over time.