Comparison of normal and abnormal coral tissue using microskeletal traits in massive Porites

Date
2016-05
Authors
Hong, Corinna
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Publisher
University of Hawaii at Manoa
Abstract
Massive Porites evermanni and P. lobata colonies in Hawai‘i have historically been observed with demarcated and raised growth anomalies (GAs). Following Hawai‘i’s mass coral bleaching event in September 2014, growth anomalies on P. evermanni and P. lobata colonies in Lanikai became more pronounced. Growth anomalies appear as noticeable masses of enlarged skeleton and tissue with larger and fewer polyps compared to the adjacent normal tissue. Some corallites in the growth anomaly region even contain additional septa. The purpose of this study was to measure corallite size in normal tissue and growth anomaly tissue. P. evermanni and P. lobata skeletons collected in Lanikai were photographed at 18x using a Nikon Coolpix 4500 attached to a stereo microscope. Ten corallites were measured from each sample using 24 X-Y coordinates mapped on landmark skeletal structures relating to septal length and overall corallite size. The ten sets of 24 coordinates were then averaged to obtain the best representation of corallite size for the sample. The morphometrics of the normal skeletons and the GA skeletons were compared using a principle component analysis and a stepwise discriminant analysis. The P. evermanni jackknifed classification matrix correctly classified 71% of GA samples and 84% of normal samples. The P. lobata jackknifed classification matrix correctly classified 77% of GA samples and 87% of normal samples. Results indicate that corallite structures appear to differ between normal and growth anomaly Porites species samples. Future studies should look at how the presence of growth anomalies affects overall colony growth and reproduction.
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Keywords
Coral, Porites lobata, Porites evermanni, growth anomaly, morphometrics
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