Heavy metals are released into the environment by natural processes, such as erosion or volcanic eruption, and by human activities. Smelting ores and burning fossil fuels release heavy metals into the environment. Depending on species, metal, and soil characteristics, plants can absorb heavy metals through the root system and incorporate them into tissue, ultimately releasing contaminants into the food chain. Heavy metals can be measured in the soil and plant tissue, but in the absence of stunting or death, it is not immediately clear if the contaminant load affects organisms’ development and metabolism. Fluctuating asymmetry (FA), which consists of random deviations of morphological traits from perfect bilateral or radial symmetry in living organisms, has been used to screen for sublethal impacts of contaminants. The aim of this study was to determine if Acer negundo (boxelder) exhibits differences in growth due to copper (Cu++) contamination.
Seedlings of boxelder were exposed to varying regimes of copper contamination (0, 5, 10, and 5/15 µmol L−1) to evaluate height growth and FA in leaves. Plant responses were widely variable within treatments.
Because the data did not meet parametric test assumptions, we used the Kruskal-Wallis nonparametric equivalent of ANOVA, which did show any measurements of FA to be statistically significant. The Gini Coefficient was used to compare the variability of FA across treatments. For between leaf comparisons our data exhibited significantly more variation within the controls than in the copper treatments. Comparisons between leaves showed no significant pattern.
To potentially measure statistically significant differences in FA using the same treatment concentrations, sample sizes would need to be much larger. Estimated sample sizes would be too large to make FA a useful bio-indicator. In summary, if the structure of this experiment did not interfere with the possible expression of FA, then these concentrations of copper do not trigger FA. This experiment represents a pilot study with potential for more extensive research on fluctuating asymmetry.
|Commitee:||Lin, Zhi-Qing, Kohn, Luci, Esselman, Elizabeth|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 81/6(E), Masters Abstracts International|
|Keywords:||Assymetry, Boxelder, Copper, Fluctuating|
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