183-7 Corals From Space: Multispectral Detection and Validation of Surviving Acropora Corals in Belize

Session: Recent Advances and New Voices in Marine and Coastal Geoscience (Posters)

Poster Booth No.: 38

Presenting Author:

Daymon Lujan

Authors:

Lujan, Daymon Thomas¹, Rose, Emmie², Baz-Aguilar, Alesandra³, Schurr, Astrid⁴, Wirth, Karl R.⁵, Das, Raja⁶, Foad, Harris⁷, Greer, Lisa⁸

(1) Environmental Studies Program, Washington and Lee University, Lexington, VA, USA, (2) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA, (3) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA, (4) Earth and Environmental Geoscience, Washington and Lee, Lexington, Virginia, USA, (5) Department of Geology, Macalester College, St. Paul, MN, USA, (6) Earth and Environmental Geoscience, Washington and Lee Universtiy, Lexington, Virginia, USA, (7) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA, (8) Earth and Environmental Geoscience, Washington and Lee University, Lexington, VA, USA,

Abstract:

Over the past four decades, Caribbean Acropora spp. corals have suffered up to 98% mortality. Acropora spp. in Belize have historically thrived but have similarly experienced a sharp decline. Before 2023, Coral Gardens, Belize, remained an ecological refuge for Acropora spp. corals. During the summer of 2023, an unprecedented marine heatwave devastated the shallow reef habitat. This study aimed to find and document surviving Acropora spp.  using a combination of satellite analysis, local ecological knowledge, and ground truthing. We used high-resolution multispectral imagery from GeoEye-1 and WorldView-2 satellites to develop a predictive habitat model in ArcGIS, applying a Random Tree Supervised Classification. The model was trained using field-verified live coral locations from Coral Gardens. We generated predictive models from satellite images from 2011, 2017, 2021, and 2023. Data showed a sharp decline in the total area of predicted live coral from 155,826 m² in 2011 to 12,737 m² in 2023, a 91.8% decrease in live coral. In June 2025, we visited 42 predicted coral sites using the 2023 model to validate model accuracy. At each location, we conducted snorkeling surveys to document the presence of A. cervicornis, A. palmata, and A. prolifera and to assess coral condition (alive, standing dead, or rubble). Twenty-eight of the 42 sites contained recently dead A. cervicornis coral framework, and 16 sites contained live Acropora spp. An additional 6 sites, identified based on input from local guides, yielded 4 confirmed instances of living Acropora spp. Given the dramatic loss of Acropora spp. in Coral Gardens, we explored the potential for Acropora to persist in deeper habitats. Six deep-water surveys were conducted at depths of 45-80 feet along the fore reef of Ambergris Caye. Live A. cervicornis was observed at a mean depth of 56 feet, with ~92% of colonies alive. Coral was further assessed for size, color, and overall health using a standardized classification index that ranged from 1 (fully bleached) to 3 (healthy). Coral averaged 2.4 on this index, with an average of 20 branches per colony and 47cm height. Data suggest remaining A. cervicornis colonies may be able to survive in deeper, cooler environments. Continued monitoring of these sites is critical for informing targeted conservation strategies.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7323

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