Converting Chemical Signatures in Vaterite Otoliths to Aragonite Otoliths in Steelhead Trout: Developing a Partition Coefficient
Otoliths are small bones near the brain of teleost fish that aid in hearing and balance. Otoliths are typically composed of a polymorph of calcium carbonate called aragonite; however, when stressed, fish may transition to producing a less dense polymorph called vaterite. Otoliths are typically used in studies of fish natal origin or migration patterns because 1) otoliths grow concentrically around an origin (birth point), 2) the material in the otolith is not replaced over time, and 3) microelements (Sr and Ba) can be incorporated into the otoliths in proportion to elemental ratios in the water (i.e., when fish move to a different water mass the new otolith material will change elemental ratios to match the water chemistry).Thus, fishery biologist have a powerful tool to track origins or movements of fish. However, these analyses only use aragonitic otoliths rather than vaterite because of the vast differences in elemental uptake rates between the two polymorphs. A large fraction of samples are thus wasted because many fish contain otoliths with vaterite. For steelhead trout (Oncorhynchus mykiss) it is important to track the migration patterns of vateritic individuals because individuals returning from Lake Erie to their natal stream to spawn tend to stray away from their natal stream to streams in different states. To be able to use vateritic individuals in microchemical analyses, a partition coefficient (Kd) must be developed to convert vaterite elemental concentrations to aragonite elemental concentrations. Developing a partition coefficient that can be used without knowledge of water chemistry elemental concentrations can allow migration patterns or origin of vaterite individuals to be determined. This would allow managers to better understand the contribution of their hatchery to the sport fish population in Lake Erie and identify if potential environmental stressors are present at their hatchery that need to be addressed to increase the survival of and return rate of individuals from their hatchery. My research compared elemental signatures in regions of aragonite and vaterite to develop this conversion factor (partition coefficient). My results demonstrated that a common partition coefficient could be developed for fish.
Marine and Aquatic Biology
Dr. Jeff Miner
First Advisor Department
Dr. John Farver
Second Advisor Department
Justice, Jamie, "Converting Chemical Signatures in Vaterite Otoliths to Aragonite Otoliths in Steelhead Trout: Developing a Partition Coefficient" (2017). Honors Projects. 243.