UTILIZING CURRENT GENERATION SATELLITES FOR MONITORING WATER QUALITY IN CARIBBEAN WATERS

In the U.S. Virgin Islands, (USVI) coral reef related marine ecosystem services account for approximately 70% of the USVI’s gross domestic product (Oliver et al., 2018). With a net positive anthropogenic migration to the area, increased human activities have resulted in deforestation and higher volume of nutrient-rich runoff and sediment flux into the reef environments (Cohn, 2013). Because of this increased volume of runoff in coastal waters, coral communities are under higher levels of stress and algae is outcompeting the coral reefs for nutrients (Koop et al., 2001). Since water quality directly impacts coral reef stress rates, it is essential to effectively monitor water quality parameters impacting reef ecosystems to determine the preservation methods that will be most robust. One tool that is increasingly being utilized is the use of optical satellite sensors. With the advancement of technology several environmental observations (EO) satellite sensors have been recently launched. By utilizing EO satellites such as ESA’s Sentinel 2 to perform optics-based characterization, various optically active water quality parameters such as chlorophyll, suspended sediment, and dissolved organic matter can be estimated and monitored on a much larger scale and temporally efficient frequency than traditional field methods (Pahlevan et al., 2017). The objective of this study is to accurately estimate chlorophyll and suspended sediments in water columns by developing regionally calibrated models. The performance of existing statistical-based band ratio models were evaluated in estimating chlorophyll levels in the USVI coastal waters. The best performing models (Rrs 430/Rrs 560) and ((Rrs 560 + Rrs 665)/2) yielded R² values of 0.33 and 0.52 respectively, with RMSE values of 0.09 and 0.07. These results show promising potential of satellite applications for future monitoring of chlorophyll-a levels in the USVI.