Developing a Non-Invasive Technique to Quantify Coral HealthEPA Grant Number: FP917097
Title: Developing a Non-Invasive Technique to Quantify Coral Health
Investigators: Hancock, Harmony A
Institution: Nova Southeastern University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2010 through August 31, 2012
Project Amount: $74,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecosystem Services: Aquatic Systems Ecology
In the face of global climate change, there has been a great deal of research into coral organisms/population response to stress, including bleaching, disease, turbidity, pollution, and acidification. Despite the importance of understanding coral status (health and/or stress), there are surprisingly no generally accepted quantitative measures of coral health. All methods to determine coral status use coral pigmentation as an indicator. Ascertaining pigment concentrations is possible through a variety of approaches. Current methods to determine coral status rely on either subjective visual assessment or highly invasive assays. There is need for a more appropriate method to quantify coral pigments to interpret status. Coral photosynthetic pigment concentrations vary in response to stress, thus optical measurements offer a means for rapid, non-invasive determination of coral status. The terrestrial plant pigment literature is replete with optical indices designed to assess plant status. These, as well as novel indices, are investigated to determine the relationship between coral photosynthetic pigment concentrations and spectral reflectance signatures. The development of a model to predict coral pigment concentration will allow for the relative status of a coral to be quantified, without the use of invasive or subjective methodology.
Coral health is a bioindicator of climate change. The most accepted proxy for coral health is coral pigmentation. Current methods to quantify pigments are either visible (and therefore highly subjective) or invasive. Bio-optical modeling is a promising alternative. This study applies a variety of mathematical treatments to determine the relationship between coral spectra and pigment concentrations. A bio-optical model is being developed, whereby coral spectra predict pigments to represent coral health.
The first stage of research will utilize known coral photosynthetic pigment concentrations derived by high performance liquid chromatography and corresponding optical spectra to determine the mathematical relationship between them. By analyzing spectral data using mathematical applications employed by terrestrial pigment researchers, a bio-optical model or spectral index will be developed to describe coral status in terms of photosynthetic pigment concentrations. Several pigment ratios and spectral indices used to remotely sense terrestrial photosynthetic pigments will be examined, including but not limited to partial least squares, stepwise and multiple linear regression, photochemical reflectance index, normalized difference vegetation index, and ratio vegetation index. The outcome of each mathematical treatment will be compared statistically to determine which accurately predicts pigment concentrations, and therefore, coral status. This bio-optical model will provide a non-invasive, quantitative method for assessing coral health necessary for consistent sampling and applicable to a wide range of reef areas.
The use of high performance liquid chromatography to determine coral pigment concentrations and corresponding optical spectra provide a paired data set to determine the relationship between them. With knowledge of the statistical relationship between pigments and spectra, as well as the best predictive spectral index for modeling of pigments, this project will provide both a method to quantify photosynthetic pigments and an alternative to invasive sampling techniques. A novel, more appropriate index for corals will also be developed based on pigment ratios and spectral indices from the terrestrial literature, as well as coral spectral features of interest. These findings will be important in providing the scientific basis for future remote sensing of reef health.
Potential to Further Environmental/Human Health Protection:
The focus of this project is to improve knowledge necessary to protect and restore the services coral reef ecosystems provide, by developing a method and subsequent optical model to repeatedly, non-invasively monitor corals. With an optical model, maps indicating status of entire tracts of reefs can be constructed (e.g., chlorophyll or NDVI maps). It is the Environmental Protection Agency’s mission to develop the underlying science to quantify ecosystem services and investigate the science involved in the protection and restoration of ecosystems. By quantifying the status of economically and aesthetically valuable coral reef ecosystems, this mission will be accomplished.