Oceans (Apr 2024)

Global Chlorophyll Concentration Distribution and Effects on Bottom Reflectance of Coral Reefs

  • Ana G. Bonelli,
  • Paulina Martin,
  • Phillip Noel,
  • Gregory P. Asner

DOI
https://doi.org/10.3390/oceans5020013
Journal volume & issue
Vol. 5, no. 2
pp. 210 – 226

Abstract

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Despite the limited coverage of coral reefs in the world’s oceans, they play a crucial role in global marine biodiversity and providing essential ecosystem services. This study explores the influence of chlorophyll-a (Chl-a) concentration in the water column on the estimation of bottom reflectance (rb) in coral reefs monitored by the Allen Coral Atlas coral reef monitoring system, using satellite imagery from a Sentinel-2 MSI sensor. We conducted a comprehensive analysis, considering Chl-a global distribution and variability, and its combined effect with water column depth over rb calculation. Our results demonstrated that the impact of Chl-a on rb estimation becomes significant when the water column depth exceeds 3 m. While suggesting the optionality of using regional Chl-a values, our study highlights potential overestimations of Chl-a in optically complex environments, such as along the Brazilian coast. This research contributes to refining coral reef monitoring systems and underscores the importance of accurate Chl-a assessments for robust environmental evaluations.

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