Study Explores Link Between Forestry Management Practices and Pesticides in Aquatic Species Details Share This Pesticides used in forestry may threaten species in downstream rivers and estuaries, but little is known about the extent to which this occurs. Pesticides used in forestry may threaten species in downstream rivers and estuaries, but little is known about the extent to which this occurs. A new study by researchers at Portland State University found mussels, clams and oysters in watersheds along the Oregon Coast are exposed to pesticides used in managing forests. The results of this study, published in the journal Toxics, have implications for developing better forest management practices that are less likely to negatively affect aquatic life.