Integrating terrestrial and benthic habitat quality into coral reef restoration, conservation, and management

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Marine protected areas (MPAs) are a major management and conservation tool used by governments around the world. The Fijian government, along with individual villages, have set up no-take MPAs within various coral reefs. Coral reefs within MPA boundaries are usually healthier, have more coral cover, and support more diverse fish assemblages than their neighbouring, non-protected reefs. The absence of fishing pressure leads to higher overall reef health; but, what other processes are occurring within the MPAs? Recent studies have shown that some larval reef fish express a preference towards the olfactory cues of vegetation that is native to their natal reef. Unpublished data also show that larval fish exhibit olfactory avoidance of many crop-plants within Fiji (i.e. mahogany, palm oil, coconut). Rainwater runoff passes through the vegetation of a watershed and picks up the olfactory cues of the inhabiting plants before draining into the ocean. In this study, we seek to understand the influence that terrestrial developments have on coral reef health and if MPAs help to offset the negative impacts of developed watersheds. To test this idea, we will use a DJI Phantom 4 quadcopter with a built-in near-IR camera to map the topography and vegetation species density of Tavewa Island in the Yasawa Archipelago of Fiji. Data were collected in still images taken with up to 80% overlap between images to create mosaic images with resolutions of five centimetres of the entire study area. Many individual images will be stitched together in a process known as Structure from Motion (SfM). Data sets extended from the island to the nearshore, shallow coral reefs fringing the island. The corals will be mapped for elevation, location, and species composition, which will be applied to restoration and conservation efforts. All terrestrial and aquatic images will be processed using Pix4D and maps will be generated and analyzed using ESRI ArcGIS. Topography, bathymetry, and species densities will be analyzed to determine if there exists a link between terrestrial developments and coral reef habitats. The use of low-cost aerial remote sensing techniques provides many opportunities for enhancing coral reef health. These technological advancements have largely not been brought into this realm of study. This study will be the first of its kind directly linking anthropogenic vegetation changes to declining coral reef health. Understanding this connection will shift how coral reefs are restored, conserved, and managed.