Fourth derivative analysis of Red Sea coral reflectance spectra

Abstract

Reflectance spectra of coral colonies and associated sand and rubble were obtained over the fringing reefs of Eilat, Israel using two GER 1500 radiometers. The overall spectral response curve of Red Sea corals displayed the same three inflection points reported for Pacific corals, with notable differences between in vitro and in situ measurements. Fourth derivative analysis of relatively pure spectra (filling the sensor's field of view) allowed for differentiation of coral and non-coral targets with 95–99% accuracy. The characteristic peaks revealed by the fourth derivative match those obtained on Hawaiian corals.

Acknowledgments

This project was supported by the Hull University Research Support Fund and NERC grant DST/26/57. Magnus Wettle's studentship is funded by Hull University. The NERC Equipment Pool for Field Spectroscopy (EPFS) and the staff at the H. Steinitz Marine Biology Centre are thanked for their enthusiastic help throughout this study.