HR: 12:05h
AN: OS22B-08    [Abstracts]
TI: UV Attenuation Near Coral Reefs in the Florida Keys: Light Absorption by CDOM and Particles
AU: * Shank, G C
EM: shank.chris@epa.gov
AF: National Research Council Research Associate, US EPA 960 College Station Road, Athens, GA 30605 United States
AU: Zepp, R G
EM: zepp.richard@epa.gov
AF: US EPA, 960 College Station Road, Athens, GA 30605 United States
AU: Bartels, E
EM: ebartels@mote.org
AF: Mote Marine Laboratory, 24244 Overseas Highway, Summerland Key, FL 33042 United States
AB: We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs physiological processes in corals and contributes to bleaching episodes. Corals in the Florida Keys experience large variations in UV exposure due to several factors including tidal exchange and fluctuating meteorological conditions. CDOM derived from mangroves and seagrass beds is the primary attenuator of UV radiation near coral reefs in our study area. CDOM accounts for more than 90 percent of the absorption of UVB irradiance (305 nm) throughout the region. However, we have determined using the quantitative filter technique that up to 25 percent of the downwelling UVA irradiance at 380 nm may be directly absorbed by suspended particles. Resuspension from within or near the reef structure appears to be the primary particle source as phytoplankton pigments typically comprise less than 20 percent of the particle UV absorption capacity near reef sampling sites. Our research also has implications for remote sensing applications as light absorbed by particles must be considered when modeling optical data from satellites. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.
DE: 4220 Coral reef systems (4916)
DE: 4264 Ocean optics (0649)
DE: 4852 Photochemistry
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005