Aquatic Plant Control Research Program. Effects of Endothall Treatment on Phosphorus Concentration and Community Metabolism of Aquatic Communities

摘要

Herbicide treatment and macrophyte senescence may results in the recycling of phosphorus from aquatic weeds to nontarget species because the nutrient is rapidly leached from plant tissue. A field study and two microcosm experiments were conducted to examine changes in phosphorus, oxygen, and chlorophyll a concentrations after the application of the herbicide and endothall. In each microcosm experiment, Potamogeton crispus communities were housed in 57-lambda aquaria containing known standing crops of the test plant and sediment with a specific phosphorus-adsorbing capacity. In the first microcosm experiment, the application of 2.0 ppm endothall caused plant death and a rapid, short-term increase in soluble reactive phosphorus, presumably from excessive leaching during senescence. A second microcosm experiment, which employed six control and six experimentally treated systems, differed from microcosm experiment I in that the sediment used had a weak phosphorus-adsorbing capacity. In addition, the metabolism of the total microcosm and three autotrophic components (macrophyte-epiphyte, planktonic, and benthic) were monitored to assess the effects of an herbicide perturbation on nontarget assemblages.