Hyperspectral imaging as a tool for assessing coral health utilising natural fluorescence

Abstract

Fluorescent proteins are a crucial visualisation tool in a myriad of research fields including cell biology, microbiology and medicine. Fluorescence is a result of the absorption of electromagnetic radiation at one wavelength and its reemission at a longer wavelength. Coral communities exhibit a natural fluorescence which can be used to distinguish between diseased and healthy specimens, however, current methods, such as the underwater visual census, are expensive and time-consuming constituting many manned dive hours. We propose the use of a remotely operated vehicle mounted with a novel hyperspectral fluorescence imaging (HyFI) “payload” for more rapid surveying and data collection. We have tested our system in a laboratory environment on common coral species including Seriatopora spp., Montipora verrucosa, Montipora spp., Montipora capricornis, Echinopora lamellose, Euphyllia ancora, Pocillopora damicornis and Montipora confusa. With the aid of hyperspectral imaging, the coral specimens’ emission wavelengths can be accurately assessed by capturing the emission spectra of the corals when excited with light emitting diodes (395–405 and 440 nm). Fluorescence can also provide an indicator of coral bleaching as shown in our bleaching experiment where we observe fluorescence reduction alongside coral bleaching.