Evaluating the sublethal impacts of current use pesticides

Evaluating the sublethal impacts of current use pesticides on the environmental health of salmonids in the Columbia River Basin Northwest Fisheries Science Center, Ecotoxicology and Environmental Fish Health Program, Seattle, WA

A quick background on pesticides. . . • The term “pesticide” refers to several broad categories of chemicals, including insecticides, herbicides, fungicides, antifoulants, and more. • Multiple federal statues address the potentially harmful effects of pesticides on “non-taget organisms” (i. e. salmon). These include the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the Clean Water Act (CWA), and the Endangered Species Act (ESA). • Pesticides are used almost everywhere, but the highest inputs to salmon habitat are usually in urban and agricultural watersheds. In western states such as Washington, ~ 750 chemicals (active ingredients) are currently registered for use. • Of these, 100+ pesticides are “significant use”, or applied in the tens of thousands of pounds in a given basin. The majority of these find their way to surface waters that support threatened or endangered salmonids via various transport processes. • All pesticides are used to kill, repel, or regulate the growth of various biological organisms. As a class of contaminants, pesticides are somewhat unusual in that they are intentionally released into the natural environment.

Zebrafish (Danio rerio)

Anatomical Screens Notochord Somites Forebrain-midbrain-hindbrain Spinal cord Heart and vasculature Liver Enteric system Kidney Eye Ear/otolith Lateral line Fins Skin and melanophores Craniofacial structures Many more…

Functional Screens Cardiovascular function Spontaneous motor activity Escape reflexes Visual system function Mechanosensory function Olfactory function Cellular pathophysiology More…

The salmon olfactory nervous system olfactory rosette olfactory nerve olfactory bulb telencephalon Gillermo Munro/Seattle Post-Intelligencer

Why use the salmon nose as a screen for sublethal neurotoxicity? • Olfactory receptor neurons (ORNs) are directly exposed to pesticides in salmon habitat. • ORNs are very sensitive, with detection thresholds for some odorants in the low picomolar (10 -12) range. • Fundamental mechanisms of olfactory signal transduction are reasonably well understood. • Direct electrophysiological measures of ORN function are straightforward. • Olfactory function has been linked to the performance and fitness of salmonids (e. g. , predator avoidance, reproductive priming, etc. ). • A salmon’s sense of smell determines, in part, the long-term genetic integrity of wild populations.

In vivo olfactory recordings vibration isolation table fiber optic illuminator microscope A data acquisition computer (Lab. VIEW) oscilloscope + - to drain peltier chiller plumbing wiring computer-controlled manifold physiological solutions chiller recirculating chiller with pump B

Short-term (30 min) copper exposures significantly reduce olfactory sensitivity in juvenile coho salmon A B post pre

Seattle Times, 7/9/2002