SS1.02 Geochemical Tracers in Calcified Structures: Implications for Fisheries Research
Date: Tuesday, June 11, 2002
Time: 4:30:00 PM
Location: Carson A
 
KrausRT, University of Maryland Center for Environmental Science, Solomons, MD 20688, USA, kraus@cbl.umces.edu
Secor, D, H, University of Maryland Center for Environmental Science, Solomons, MD 20688, USA, secor@cbl.umces.edu
 
OTOLITH SR:CA AS A SCALAR OF SALINITY IN ESTUARINE SYSTEMS: EXPECTATIONS, PATTERNS, AND PROBLEMS
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Otolith Sr:Ca chronologies of estuarine and diadromous fishes often represent expected dispersal and migration patterns across a salinity gradient, with low Sr:Ca ratios corresponding to time spent in freshwater and oligohaline habitats. Geochemical concepts, biochemical uptake models, and laboratory experiments indicate that Sr:Ca in the otolith should be proportional to Sr:Ca in the water. Across a salinity gradient of 15 to 35 ppt, environmental and otolith Sr:Ca do not substantially vary with salinity. At lower salinities, otolith Sr:Ca declines, but Sr:Ca in freshwater environments can vary widely, even exceeding marine Sr:Ca in basaltic watersheds. This contradicts expectations that otolith Sr:Ca is based solely on environmental Sr:Ca. In this presentation, we review Sr uptake models and related empirical data from laboratory experiments on juvenile American eel, American shad, and white perch. Experimental results lead us to hypothesize that there may be salinity effects on otolith Sr:Ca that are independent of environmental Sr:Ca.