Sensitivity of spectral communities to shifts in benthic composition in Hawaiʻi

Coral reef benthic communities have been mapped in broad categories, such as total coral cover, using remote sensing, yet we lack important details on how changes in benthic community composition translate to spectral changes observed in airborne and spaceborne data. Here, we carry out a spectral sensitivity analysis to enhance our quantitative understanding of benthic community reflectance spectra – or spectral communities – using a controlled simulation that incorporates field-based spectral libraries and endmember constituent modeling. Following the modeling phase, we apply the knowledge to the interpretation of airborne imaging spectroscopy data taken at 2 m resolution over two coral reefs in Hawaiʻi. We found that differences in organismic-scale spectra and their morphology contribute to patterns in the airborne data, enabling fine-scale differentiation between benthic community types. In doing so, we successfully determined the extent of two hyperdominant coral species (Porites lobata and Porites compressa) in the airborne data. Our findings suggest that imaging spectroscopy remains only partially explored for its potential in more detailed benthic mapping. Additional research that combines field- and remote sensing-based spectroscopy may advance ecosystem research and management on coral reefs.