Assessing Ecosystem Health of an Agricultural Watershed Using Insect Condition
Streams become contaminated with pesticides through runoff, groundwater contamination and aerial deposition. Previously, a research team had determined that aquatic insects are negatively affected by insecticides at concentrations that are detected in streams in Atlantic Canada. These concentrations were so low that they were not thought to cause effects. It was found that mayflies were smaller, less fit and always female when exposed to insecticides in artificial streams. In some cases, we saw these effects even at the lowest concentrations (0.1 parts per billion). Thus, the intern will evaluate the combined effects of pesticides and nutrients on real streams in the Grand Falls area of New Brunswick. This work will help the team to evaluate how many mayflies are present in a northern New Brunswick watershed and determine whether changes in size and fitness are cause for concern. Ultimately, change in insect size and diversity will then be related to ongoing mesocosm (artificial stream) experiments. The field measurements will link effects detected in the environment to know stressors, such as individual pesticides and nutrient concentrations. Establishing this baseline is important for developing environmentally-relevant guidelines and improving existing regulations.