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A Comparison of the Diagnostic Accuracy of in-situ and Digital Image-Based Assessments of Coral Health and Disease

2020; Frontiers Media; Volume: 7; Linguagem: Inglês

10.3389/fmars.2020.00304

2296-7745

John H. R. Burns, Grady Weyenberg, Travis Mandel, Sofia B. Ferreira, Drew Gotshalk, Chad K. Kinoshita, Micah Marshall, Nicholas A. V. Del Moral, Shane J. Murphy, Kailey H. Pascoe, Alexandra Runyan, Alexander Spengler, B. Wells, Danielle K. Wilde, Roberto Pelayo,

Coral and Marine Ecosystems Studies

The prevalence of coral disease is steadily increasing throughout the global ocean and there is a growing need for efficient methods for detecting and monitoring coral health. At present, coral health assessments are primarily conducted using in-situ surveys, which record visual observations of disease in the field. Recent technological advancements allow researchers to instead collect high-resolution imagery of benthic habitats, and these images can be used in conjunction with digital tools to assess the health of coral colonies at a later time. However, little is known about the relative efficacy or diagnostic accuracy of these two approaches. This study contrasts the diagnostic accuracy of in-situ and digital methodologies for detecting diseases affecting corals. Multiple 1-m$^2$ plots are surveyed on coral reefs located on both the windward and leeward side of Hawaii Island. For each plot, an in-situ visual analysis of coral health is conducted by a diver and images are collected and rendered into a high-resolution orthomosaic for subsequent digital analysis. Both methods assess the same coral colonies, resulting in paired health diagnoses for multiple health conditions. Lacking a gold-standard diagnosis of disease, a latent class model is used to estimate the sensitivity and specificity of both methods. We find that in-situ assessments of coral health have a higher sensitivity and lower specificity in detecting diseases when compared to digital analyses based on orthomosaics. However, the effect size is relatively modest, indicating that while the in-situ method provides a more sensitive diagnostic approach, the techniques are of comparable accuracy and should both be considered viable methods of characterizing and monitoring coral health.