Comparing Low-Cost DIY and Research-Grade Hyperspectral Imaging as Coral Reef Monitoring Tools

Hyperspectral imaging (HSI) is emerging as a promising tool in scientific endeavours, including non-invasive quantification of pigments, an area of research with many use cases. Here, we tested the efficacy of a low-cost (~USD $200) and open-source HSI device (400 – 1000 nm, a spectral resolution of ~2 nm FWHM) in coral bleaching research. Specifically, we evaluated its ability to quantify the concentration of key photosynthetic pigments (chlorophyll a, chlorophyll c2, diadinoxanthin, peridinin, and total pigment content) was compared against a research-grade (~USD $70,000) commercial hyperspectral camera using coral fragments subjected to varying levels of thermal stress. The low-cost HSI acquired coral reflectance spectra that were similar to the commercial hyperspectral camera, with a mean spectral angle of 11.38 ± 3.82°. However, the low-cost device was unable to resolve differences in spectral magnitude to the same accuracy as the commercial HSI and did not detect differences among coral fragments at different levels of thermal stress. Thus, the current HSI device prototype is better suited for classification and diagnostic applications where spectral shape is of greater importance than spectral magnitude. Partial Least Squares Regression models built from the reflectance spectra of each HSI instrument showed very similar yet moderate performance when predicting key coral pigments (Commercial HSI mean %RMSEP = 22.8%, low-cost HSI = 22.12%). While the current design of the low-cost HSI device has clear limitations, the results show potential in a system that costs a fraction of commercial alternatives. Continued development of low-cost HSI platforms is accelerating rapidly across a variety of fields in environmental research, and improved designs have the potential to enhance coral reef monitoring and restoration efforts globally.