Wallin, David O., and Jacqui Bergner. 2024. “Evaluation of Recreational Impacts on Eelgrass Using Unoccupied Aerial Systems and Virtual Ground Truth Data.” Journal of Coastal Research. doi: 10.2112/JCOASTRES-D-24-00020.1.
Abstract
elgrass (Zostera sp.) provides a wide variety of ecosystem services and habitat for many organisms. Eelgrass distribution can be adversely affected by many factors, including recreational boating activities. Imagery acquired using unoccupied aerial systems (UAS) has recently been adopted as an effective approach for monitoring eelgrass in nearshore marine environments. Effective use of UAS imagery for eelgrass monitoring requires ground truth data, which can be quite challenging to collect during brief low-tide events. This project presents a novel approach for collecting “virtual” ground truth data that was used in conjunction with UAS imagery to quantify the percent coverage of eelgrass and algae in the intertidal and upper subtidal zones and changes in coverage in response to recreational impacts and seasonal dynamics.
Figure 9. Change in total percent vegetation cover between (a) 14 and 17 July, (b) 17 and 31 July, and (c) 31 July and 28 August. Negative values represent loss of vegetation cover and positive values represent increase in vegetation cover. Arrow in (a) indicates loss of subtidal eelgrass presumably caused by outboard motor propellers and regrowth of this eelgrass in (b).
