HR: 16:45h
AN: H44A-06    [Abstracts]
TI: Isotopic Evidence for Chemosynthetic Contributions to the Subterranean Food Web of the Upper Floridan Aquifer
AU: * Opsahl, S
EM: stephen.opsahl@jonesctr.org
AF: J. W. Jones Ecological Research Center, Route 2, Box 2324, Newton, GA 39870 United States
AU: Chanton, J
EM: jchanton@mailer.fsu.edu
AF: Florida State University, Oceanography Department Rm. 317 OSB, West Call St. Florida State University , Tallahassee, FL 32306 United States
AB: The possibility that subterranean life in the Upper Floridan aquifer can proliferate through a microbial food web based on chemosynthesis was examined using multiple isotopic measurements (¹³C, ¹⁴C, and ¹⁵N) on the tissues of obligate aquifer-dwelling (troglobitic) macrofauna of the Upper Floridan aquifer. Specimens that were captured at the mouth of springs along streams had δ¹³C values that reflected terrestrial vegetation as a primary food resource. In contrast, highly depleted δ¹³C values were measured in the tissues of some specimens which came from areas that were distant from any natural direct conduits to the land's surface. The highly depleted δ¹³C signature exhibited by these subterranean organisms was well beyond those observed in biota supported by terrestrial photosynthetic production, but were consistent with microbial chemosynthetic pathways. Evidence for chemosynthesis was also provided by differences in Δ¹⁴C values. Thus, multiple sources of energy appear to be fueling the subterranean food web of the aquifer.
DE: 1615 Biogeochemical processes (4805)
DE: 1831 Groundwater quality
DE: 1845 Limnology
DE: 1890 Wetlands
DE: 4870 Stable isotopes
SC: Hydrology [H]
MN: 2005 Joint Assembly