TEMPORAL BIOMONITORING USING WILD CELERY, VALLISNERIA-AMERICANA

This study was carried out to assess the effects of sediment type, loc al water column, source of plants, and duration of exposure between 19 90 and 1994 upon growth, survivorship and reproduction of Vallisneria americana at two sites in the Huron-Erie corridor of the Great Lakes. The major objective was to determine whether year-to-year variations a ffect consistency of results using Vallisneria as a biomonitoring tool . Relative annual rankings of results from experimental treatments did not change over a 4-year period. However, most of the absolute measur es of plant performance varied significantly between years. Effects on plant growth and development were associated primarily with exposure to water columns, and secondarily, to sediments. Measures of plant den sity, rate of clonal growth, leaf length, number of leaves per m(2), a nd plant biomass per m(2) were unusually high in the first year compar ed with the subsequent 3 years, perhaps due to disturbance associated with set-lip of the experiment. Leaf-to-root surface area ratios provi ded a simple, consistent, and reliable measure of environmental qualit y. Other measures of plant performance varied significantly from year- to-year and, therefore, are not advised for long-term comparisons. Res ults of this study indicate that Vallisneria can be an effective tempo ral biomonitor of environmental quality.