May 11, 2021 — Oysters, estuarine clams and freshwater mussels in watersheds along the Oregon coast contain pesticides used in managing forests, according to a study funded by Oregon Sea Grant.
Researchers from Portland State University found pesticides in 38 percent of the tissue samples. Indaziflam, an herbicide currently used in Oregon forestry, was found in about 7 percent of the samples. Contaminants also included pesticides used in orchards, Christmas tree farms and homes, as well as banned pesticides, including DDT byproducts.
The study, published in the journal Toxics, may help guide forest management practices to reduce the amounts of forestry chemicals entering aquatic ecosystems.
The study was led by Kaegan Scully-Engelmeyer, a doctoral student in the earth, environment and society program at PSU, and PSU marine ecologist Elise Granek.
They collected tissue samples from freshwater western pearlshell mussels — softshell clams typically found in the upper area of estuaries — and Pacific oysters. They collected them from watersheds along the Oregon coast in 2017 and 2018. These organisms are good indicators of environmental contamination because they are sedentary filter feeders.