Effects of Light and Nutrient Availability on the Growth and Reproduction of the Aquatic Plant Wild Celery (Vallisneria americana)
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Freshwater habitats have changed over time as a result of anthropogenic effects in the form of fertilizers and soil runoff from erosion. The increased nutrient availability and turbidity of the water has been shown to have an effect on certain freshwater plant species. Vallisneria americana (wild celery) is a freshwater plant species of particular ecological significance. It is a common duck and muskrat food and offers protection to small organisms. The object of this experiment was to grow V. americana under controlled conditions that varied light and nutrients to see how it may respond to the anthropogenic effects of increased nutrient availability and turbidity. V. americana was planted in large plastic containers under four different conditions: ambient Iight/high nutrients, ambient light/low nutrients, shade/high nutrients, and shade/low nutrients. Observations of plant growth and reproduction were taken over a period of 52 days. Leaves of V. americana grown in shade conditions grew tall and narrow and the plants produced many tubers, although new shoot production along lateral rhizomes was low. Plants grown in ambient light had leaves that were wider and shorter than that of shade treatments and produced many new shoots. In contrast, nutrients alone did not seem particularly important to plant growth or reproduction. We suggest that the effects of light availability on Vallisneria americana will have consequences for aquatic fowl populations. Diving ducks should be favored by high water turbidity, since they primarily eat tubers. However, dabbling duck should thrive on plants grown in ambient light because the overall amount of available above ground vegetation may be greater.