Remote sensing and in-situ optical measurements of resuspended sediments in coral reefs and seagrass beds
Gerardo
Toro-Farmer, Biology Department - University of Southern California, torofarm@usc.edu
(Presenting)
Dale
A
Kiefer, Biology Department - University of Southern California, kiefer@usc.edu
Burton
H
Jones, Biology Department - University of Southern California, bjones@usc.edu
High concentrations of Total Suspended Sediments (TSS) modify the spectrum of light reaching corals and seagrasses, limiting their photosynthetic rates and eventually resulting in the death of these organisms. Navigation channels have been created in the Bermuda Islands to allow access of large commercial and cruise ships to the main ports. Ship traffic resuspends sediments which then are transported to reefs and seagrass beds. We have begun conducting a study of the utility of satellite images to monitor such resuspension and its impacts on the water column optical properties of reefs in Bermuda. In-situ spatial-temporal variations in the inherent optical properties (IOPs) as well as in the particle size distribution (PSD) and concentration were measured in order to estimate the amount and composition of materials being resuspended from the seafloor and to study how the spectral quality of light reaching the reef is being affected by these resuspension events. Additionally, in-situ measurements were compared with data retrieved for the same dates from the MODIS sensor at its higher spatial resolution (Band 1, 250m). Although MODIS can provide decent estimations of sediment concentrations from this band, studies of changes in the water column IOPs by suspended particles in coastal ecosystems are limited by this sensor’s low spatial and spectral resolution. In order to fully integrate in-situ and remote sensed optical measurements as a tool for studying local processes and for long term monitoring programs in coastal areas, new high spatial and spectral resolution sensors are needed onboard future EOS missions.
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