Underwater hyperspectral classification of deep sea corals exposed to 2-methylnaphthalene.

Coral reefs around the world are under threat due to anthropogenic impacts on the environment. It is therefore important to develop methods to monitor the status of the reefs and detect changes in the health condition of the corals at an early stage before severe damage occur. In this work, we evaluate underwater hyperspectral imaging as a method to detect changes in health status of both orange and white color morphs of the coral species Lophelia pertusa. Differing health status was achieved by exposing 60 coral samples to the toxic compound 2-methylnaphthalene in concentrations of 0 mg L-1 to 3.5 mg L-1. A machine learning model was utilized to classify corals according to lethal concentration (LC) levels LC5 (5% mortality) and LC25 (25% mortality), solely based on their reflectance spectra. All coral samples were classified to correct concentration group. This is a first step towards developing a remote sensing technique able to assess environmental impact on deep-water coral habitats over larger areas.
Competing Interests: We have the following interests. This study was partly financed by Statoil, ConocoPhillips Skandinavia, Dea Norge, ENI Norge, Lundin Norway, Total E&P Norge, Norwegian Deepwater Programme, Ecotone, and Akvaplan-niva (RCN project number 235440/E30). The exposure experiment received financial support from the project “Species Sensitivity Distribution for Deep Sea Species and Toxicity of continuous and spiked exposures to crude oil at 1 atm for deep sea species,” led by Akvaplan-niva and financed by the American Petroleum Institute (API). PAL and IMH are employed by Ecotone. LMSA and IE were employed by Ecotone and Statoil, respectively, at the time of submission of original manuscript. Statoil Technology Invest is the main shareholder of Ecotone AS. PAL, IMH and LMSA are also shareholders in Ecotone AS. Ecotone AS is the owner of patent no. NO/EP2286194 titled “Underwater Hyperspectral Imaging.” Based on this patent, Ecotone sells scientific instruments for underwater use to the scientific community, under the product name Underwater Hyperspectral Imager (UHI). Ecotone AS has two pending patent applications. LMSA and IMH are involved as inventors. Ragnhild Pettersen, Luca Tassara, Lionel Camus and Jenny Bytingsvik are employed by Akvaplan-niva AS. There are no further patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide for authors.