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A comparison between boat-based and diver-based methods for quantifying coral bleaching

March 31, 2015

Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

Publication Year 2015
Title A comparison between boat-based and diver-based methods for quantifying coral bleaching
DOI 10.1016/j.jembe.2015.02.017
Authors David G. Zawada, Rob Ruzicka, Michael A. Colella
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Experimental Marine Biology and Ecology
Index ID 70144464
Record Source USGS Publications Warehouse
USGS Organization St. Petersburg Coastal and Marine Science Center