This study tested the hypothesis of recent evolution of trophic polymorphism in Jo Jo Lake kokanee. We found no genetic or morphological distinctions between the putative piscivorous and nonpiscivorous morphotypes. Dietary data suggest an ontogenetic diet shift from benthic macroinvertebrates to piscivory. While there is no evidence of a species pair, Jo Jo Lake kokanee show morphological evidence of ongoing trophic adaptation to piscivory.
This study also examined the trophic ecology of mercury in Jo-Jo Lake. We used stable isotopes of carbon and nitrogen to interpret trophic patterns of mercury concentrations and to test the hypothesis that foraging on limnetic resources results in higher mercury concentrations than does foraging on benthic resources. Mercury concentrations in baseline primary consumers were higher in the limnetic food web than in the benthic food web. However, hierarchical modeling using an information theoretical approach suggested that bioaccumulation and biomagnification are more important for explaining variation in mercury concentrations than habitat-specific foraging in Jo Jo Lake.
|Advisor:||Hippel, Frank A. von|
|Commitee:||Causey, Douglas, Pavey, Scott A., Rainey, Fred A.|
|School:||University of Alaska Anchorage|
|School Location:||United States -- Alaska|
|Source:||MAI 52/01M(E), Masters Abstracts International|
|Subjects:||Ecology, Toxicology, Surgery, Evolution and Development|
|Keywords:||Alaska, Geometric-morphometrics, Microsatellites, Ontogenetic diet shift, Stable isotopes, Trophic polymorphism, Trophic web|
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