HR: 1340h
AN: H13E-1370    [Abstracts]
TI: Striped Bass Habitat use in the San Francisco Estuary Determined Using Otolith Microchemistry Techniques
AU: * Phillis, C C
EM: corey@berkeley.edu
AF: Department of Earth and Planetary Science, University of California, Berkeley, 307 McCone Hall, Berkeley, CA 94720
AU: Ostrach, D J
H13E-1370 AF: Department of Pathology, Microbiology & Immunology, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616
AU: Weber, P K
H13E-1370 AF: Chemical Biology and Nuclear Science, Lawrence Livermore Laboratory, L-231, P.O. Box 808, Livermore, CA 94551
AU: Ingram, B L
H13E-1370 AF: Department of Earth and Planetary Science, University of California, Berkeley, 307 McCone Hall, Berkeley, CA 94720
AU: Zinkl, J G
H13E-1370 AF: Department of Pathology, Microbiology & Immunology, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616
AB: Habitat use has been shown to be an important factor in the bioaccumulation of contaminants in striped bass ( Morone saxatilis). This study explores techniques to determine migration in striped bass as part of a larger study investigating maternal transfer of xenobiotics to progeny in the San Francisco Estuary. The timing of movement of fish between salt and fresh water can easily be determined using a number of chemical markers in otoliths. Determining movement within estuaries, however, is a more difficult problem because mesohaline geochemical signatures approach the marine end member at very low salinities. Two tracers were used to reconstruct the migration history of striped bass in the San Francisco Estuary: Sr/Ca (measured by electron microprobe and LA-ICP-MS) and Sr isotope ratio (measured by LA-MC-ICP-MS). Both tracers can be used to map the salinity the fish is exposed to at the time of otolith increment deposition. Salinity, in turn, is mapped to location within the San Francisco Bay estuary based on monthly salinity surveys. The two methods have their respective benefits. Sr/Ca can be measured with higher spatial resolution (<10 microns). Sr isotope ratios are not modulated by metabolism. Sr isotope measurements were made to check the Sr/Ca results. In the San Francisco Estuary, low ⁸⁷Sr/⁸⁶Sr (0.706189) river water mixes with high ⁸⁷Sr/⁸⁶Sr (0.709168) marine water to 80% of the marine signal (0.7085) when the salinity is only 5% (1.8 ppt) seawater, and 95% of the marine signal (0.7090) at salinities of 20% (6.6 ppt) seawater (Ingram and Sloan, 1992). This salinity model should map directly to the otolith because there is no biological fractionation of Sr isotopes. The Sr/Ca otolith and salinity models predict a similar response. For both models, calculated otolith salinity is mapped to location within the San Francisco Estuary based on monthly salinity surveys. Using previously published salinity models, the otolith Sr/Ca and Sr isotope results are offset. These results suggest that a new Sr/Ca salinity model must be developed for this population of striped bass.
DE: 0442 Estuarine and nearshore processes (4235)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1065 Major and trace element geochemistry
DE: 1094 Instruments and techniques
SC: Hydrology [H]
MN: Fall Meeting 2005