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Quantifying exceptionally large populations of Acropora spp. corals off Belize using sub-meter satellite imagery classification
Bulletin of Marine Science (2016)
  • James Busch
  • Lisa Greer
  • David Harbor
  • Karl Wirth
  • Halard Lescinsky
  • Allen H Curran
  • Kirsten de Beurs
Abstract
Caribbean coral reefs have experienced dramatic declines in live coral cover in recent decades. Primary branching framework Caribbean corals, Acropora cervicornis (Lamarck, 1816) and Acropora palmata (Lamarck, 1816), have suffered the greatest collapse. Coral Gardens, Belize, is one of few remaining, and perhaps the largest, refugia for abundant, healthy, but undocumented populations of both Acropora species in the Caribbean Sea. In the present study, GeoEye-1 multispectral satellite imagery of a 25 km2 reefal area near Ambergris Caye, Belize, was analyzed to identify live Acropora spp. cover. We used a supervised classification to predict occurrence of areas with live Acropora spp. and to separate them from other benthic cover types, such as sandy bottom, seagrass, and mixed massive coral species. We tested classification accuracy in the field, and new Acropora spp. patches were mapped using differential GPS. Of 11 predicted new areas of Acropora spp., eight were composed of healthy Acropora spp. An unsupervised classification of a red (Band 3):blue (Band 1) ratio calculation of the image successfully separated Acropora corals from other benthic cover, with an overall accuracy of 90%. Our study identified 7.58 ha of reef dominated by Acropora spp. at Coral Gardens, which is one of the largest populations in the Caribbean Sea. We suggest that Coral Gardens may be an important site for the study of modern Acropora spp. resilience. Our technique can be used as an efficient tool for genera-specific identification, monitoring, and conservation of populations of endangered Acropora spp.
Disciplines
Publication Date
April, 2016
DOI
10.5343/bms.2015.1038
Citation Information
James Busch, Lisa Greer, David Harbor, Karl Wirth, et al.. "Quantifying exceptionally large populations of Acropora spp. corals off Belize using sub-meter satellite imagery classification" Bulletin of Marine Science Vol. 92 Iss. 2 (2016) p. 265 - 283
Available at: http://works.bepress.com/karl_wirth/27/