Spatial Variation in Coral Diversity and Reef Complexity in the Galápagos: Insights from Underwater Photogrammetry and New Data Extraction Methods

Corals in the Galápagos present diverse reef configurations from biogenic coral reefs to coral communities growing on rocks and sand. These corals have experienced decades of disturbances including recurring El Niño and mass bleaching events. However, traditional methods in ecology have limited capacity in describing coral demographic trends across large spatial scales. Therefore, the adverse effects of climate change on these reefs remains unclear. To bridge this gap we surveyed seven reef sites across the archipelago using underwater photogrammetry. We present new methods for 3D annotation and fractal dimension calculation. Our findings reveal variation in coral cover, diversity, and structural complexity across the archipelago. Our results align with previous studies in the region and add important information on reef structural complexity which was not measured here before. We release a unique dataset: Galápagos_3D, including seven 3D models and over 17,000 annotated images from the region. Our study provides an important baseline for long-term monitoring, research, and conservation in the Galápagos. Such studies can lead to new discoveries in coral ecology regarding for example recovery capacity and resilience, and help to establish evidence-based policies in the region and beyond.