Year: 2025
Type: article
Abstract: Introduction Coastal infrastructure and property, as well as intertidal wetlands, are increasingly being threatened by shoreline erosion; a consequence of human activities and climate change. Nature-based solutions, such as intertidal engineered oyster reefs, can reduce erosion and promote sediment accretion, thereby promoting the restoration and persistence of salt marshes and preventing the loss of coastal lands. Engineered oyster reef substrate and design options have rapidly expanded in the last decade, yet our understanding of how these approaches influence ecosystems and intertidal morphology is limited. Drones (or small uncrewed aerial systems [sUAS]) coupled with structure-from-motion (SfM) photogrammetry have recently been suggested as a low-cost method that offers optimal spatial coverage, fine-scale resolution, and high vertical accuracy for monitoring changes around living shorelines. Methods We evaluated how using different vertical and horizontal uncertainty thresholds for detection of drone-based shoreline change can influence interpretation of performance of engineered oyster reefs on coastal morphology and vegetation. We monitored three sites with engineered oyster reefs installed in 2020 and one reference site located on Carrot Island along Taylor Creek in Beaufort, NC, USA. Results Comparisons of the Digital Elevation Models (DEMs) and orthomosaics derived from the drone imagery revealed all sites saw marsh edge retreat from 2022 to 2023 (2-3 years post-restoration), and all sites except one low-relief oyster reef site saw elevation loss. Elevation loss was highest at the control site, but marsh edge retreat was highest at one of the engineered oyster reefs. Discussion While horizontal thresholds did not yield statistically different results, vertical thresholds did. Our results support using a 95% confidence interval for conservative volumetric estimates and recommend that future studies consider aligning uncertainty thresholds with monitoring goals and timelines.
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,077
Funders: National Science Foundation, U.S. Department of Defense, East Carolina University, U.S. Coastal Research Program, National Oceanic and Atmospheric Administration, U.S. Fish and Wildlife Service, North Carolina Sea Grant, North Carolina State University, U.S. Army Corps of Engineers, NOAA Sea Grant, North Carolina Policy Collaboratory
Awards: G3714798058, G3808732962, G4390919567, NRT-HDR: Finding Signal in the Noise to Enable Science-Based Community Response to Change in Coastal Region, G5799922587, G6758173211, DISES: Drivers of Ecosystem-based Adaptation to extreme events in mangrove-reef social-ecological systems, EVALUATING THE COASTAL PROTECTION AND ECOLOGICAL CO-BENEFITS OF NOVEL MARSH-OYSTER RESTORATION APPROACHES, G89204738
OpenAlex ID: W4413545602