High-resolution UAV mapping for investigating eelgrass wasting disease over the west coast of North America

Eelgrass habitats provide important services to coastal regions including primary production, carbon storage, nutrient cycling, habitat for fisheries species, and erosion control. However, there are widespread die-offs of eelgrass throughout the west coast of North America in the past three decades due to the impacts of wasting disease. Rigorously quantifying ecosystem-level impacts of disease to changes in the extent and density of eelgrass habitat has not yet been attempted across spatial scales. Unmanned Aerial Vehicle (UAV) or drone mapping with its high spatial resolution, temporal flexibility and ability to repeat photogrammetry affords a significant advancement on other remote sensing approaches for coastal mapping, vegetation monitoring, and environmental management. In this interdisciplinary collaborative project, we perform UAV mapping along the west coast of North America to measure eelgrass meadow extent, patchiness, and dynamics in coordination with in situ samplings in summer of 2019, fieldwork in Washington, Oregon, California, Alaska, and Canada. Biological ground-truthing across a range of points within each eelgrass meadow is used to validate drone mapping imagery. Object-oriented analysis is then performed to quantitatively estimate the link between extent/density of eelgrass habitat estimated by UAV mapping and the presence of wasting disease. This high-resolution mapping will be repeated over three years. High-resolution satellite remote sensing data are also considered and combined with drone observations at both high spatial and high temporal resolution, producing continuous mapping and monitoring for eelgrass extent and density.