Site Selection for Coral Reef Restoration Using Airborne Imaging Spectroscopy

Abstract

Over the past decade, coral restoration efforts have increased as reefs continue to decline at unprecedented rates. Identifying suitable coral outplanting locations to maximize coral survival continues to be one of the biggest challenges for restoration practitioners. Here, we demonstrate methods of using derivatives from imaging spectroscopy from the Global Airborne Observatory (GAO) to identify suitable coral outplant sites and report on the survival rates of restored coral at those sites. Outplant sites for a community-based, citizen science outplant event in Bávaro, Dominican Republic, were identified using expert-defined criteria applied to a suitability model from data layers derived from airborne imagery. Photo quadrat analysis of the benthic community confirmed the accuracy of airborne remote sensing maps with live coral cover averaging 3.5–4% and mean algal cover (macro algae and turf) ranging from 28 to 32%. Coral outplant sites were selected at 3–7 m depth with maximized levels of habitat complexity (i.e., rugosity) and live coral cover and minimized levels of macroalgal cover, as predicted by the imaging spectrometer data. In November 2019, 1,722 Acropora cervicornis fragments (80–180 mm in length) were outplanted to these sites. Surveys conducted in January 2020 in four of these sites confirmed that 92% of outplants survived after 3 months. By October 2020 (11 months after outplanting), survivorship remained above 76%. These results demonstrate higher than average success rates for coral outplant survival for this species. An online tool was developed to enable replication and facilitate future selection of coral restoration sites. Our objective is to present a case study that uses GAO-derived map products within a suitability model framework to provide a quantitative and replicable method for selecting coral restoration sites with the goal of increasing outplant survival over time.

From polyps to pixels: understanding coral reef resilience to local and global change across scales

“…However, the ability of these methods to scale to ecosystem level restoration is unclear (Boström-Einarsson et al 2020;Hein et al 2020) and more work is needed to integrate out-planting with existing ecological and physical bounds of the system (Ladd et al 2019). Examples using synoptic-scale observations to enhance coral restoration projects includes linking coral outplanting successes and failures to remotely sensed drivers on a global scale (Foo and Asner 2021), and using live coral and algal mapping for restoration site selection (Schill et al 2021).…”

Habitat suitability models of elkhorn coral provide ecological insight to support coral reef restoration

“…Indeed, new remote sensing methods are delivering unprecedented performance in high spatial resolution data for shallow coastal seascapes (Hedley et al 2016;Purkis 2018). These technological advances in remote sensing combined with high-performing predictive modeling techniques provide analytical tools to predict habitat suitability using a combination of spatial proxies for unmeasured ecological patterns and processes (Sekund & Pittman 2017;Schill et al 2021aSchill et al , 2021b. However, few studies have applied these spatially explicit ecological approaches to coral restoration.…”