Maps In Action

Photo © Paul A. Selvaggio

The suite of map products presented here have already been put to work to advance conservation work in the Caribbean. Scroll down to read about these conservation successes.

Informing coral outplanting efforts from Airborne maps

Maps developed by the GAO have already been used to support coral outplanting efforts in the Dominican Republic. Based on local knowledge and expertise, TNC's on-the-ground coral managers identified ideal ranges of different variables such as percent algal cover, habitat complexity (rugosity), live coral cover, and bathymetry. These ideal ranges were mapped out within an area that was logistically favorable and used to select a specific outplanting site.

Coral Mania - Bavaro, Dominican Republic. Photo by Manlio Leggio.

Asexual propagation is a popular and widespread technique for coral restoration. Coral outplanting is normally conducted from water-based nurseries located nearby restoration sites. In the Dominican Republic, the process of outplanting corals has been propelled by fostering the participation of local people in events known as "coral manias". In the past, sites were selected solely through local knowledge and observations. The Nature Conservancy and Arizona State University's Center for Global Discovery and Conservation Science have taken a step forward by developing a decision support tool to inform site selection based on environmental criteria derived from GAO maps. The tool, coupled with local knowledge, was successfully implemented during a coral mania organized by Fundación Grupo Punta Cana in Cabeza de Toro, Bavaro. This event brough together dozens of volunteers belonging to NGOs, Dominican environmental authorities, dive operators and other local stakeholders aimed to outplant 1,711 Acropora cervicornis fragments. This case study proved to be effective in selecting suitable sites for coral outplants and represents a promising area of research for scaling up restoration efforts. 

Photogrammetry to monitor coral restoration in the USVI

The US Virgin Islands (USVI) Coral Innovation Hub, located on the island of St. Croix, is part of TNC’s Caribbean Coral Strategy with the overarching objective to Develop and deploy scalable solutions to improve coral reef health and maximize the benefits reefs provide to people and nature in a changing climate. The USVI Coral Innovation Hub includes a land-based coral nursery and research lab, as well as several in-water coral nurseries, where sexual and asexual coral propagation approaches are being applied and tested for large-scale coral restoration. With the goal of developing novel technologies and monitoring protocols to accurately and efficiently quantify the impacts of reef conservation efforts, the USVI Coral Innovation Hub is applying photogrammetric techniques to monitor coral restoration projects in the territory.

Cane Bay, St. Croix, US Virgin Islands. Structure-from-Motion data collected at different timepoints allows powerful growth and erosion change detection using both the photomosaics and digital surface models. Left: pre-outplanting. Center: post-outplanting. Right: change detection showing accretion/growth (yellow) and erosion (red) following coral outplanting.

By sampling at time-points before, during, and after restoration activities, TNC coral scientists in the USVI are combining conventional reef monitoring surveys (e.g., Atlantic and Gulf Rapid Reef Assessment (AGRRA) diver surveys of benthos and fish) with standardized close proximity photogrammetric techniques (e.g., Structure-from-Motion) to regularly collect and analyze photomosaic and digital surface model products to monitor changes in coral restoration and control (unrestored) sites. The digital surface models generated from stereo photos, enable the monitoring of small changes in coral growth and loss at millimeter scale based on changes in the three-dimensional structure. With this information, TNC coral scientists can monitor changes in the reef, such as rugosity or structural complexity. These data are key for quantifying coral reef habitat restoration impacts in time and space, enabling comparison of changes to the reef structure in restored versus unrestored sites.  Analysis of the effects of restoration on structural complexity and rugosity are especially pertinent for coral restoration projects that aim to maintain or enhance reefs for coastal protection and essential habitat for fishes and other reef-associated organisms.

In the USVI this monitoring approach and technology continues to be developed to meet the needs of different restoration projects. For example, the photo collection method has to be adapted to the parameters of a given site (shallow versus deep, transects versus plots) and algorithms are being iterated to derive the metrics that are most useful.