Pacific Lamprey Exposed to Contaminants: A) Effects of Contaminated Sediment on Larval Growth and Development, and B) Impacts of Herbicides in Adult Lamprey

Long and short term exposures to environmental contaminants may lead to changes in developmental and reproductive success in Pacific lamprey populations and ultimately contribute to population declines.  Two separate projects are aimed to assess physiological and behavioral effects of contaminated sediments and herbicides on Pacific lamprey.  Larval and adult Pacific lamprey were obtained from the Siletz River and transported to the Fish Performance and Genetics Laboratory where trials began after a 3 week acclimatization period.  The first project focused on ammocoete growth and development utilizing sediments collected from the Portland Harbor Oregon Superfund site.  Effects of long term exposure to polluted sediments were measured in individual ammocoetes held in mesh enclosures for 30 and 60 day trials.  Methods developed for conducting a growth experiment were validated when significant weight and length increases were achieved in 3” diameter mesh enclosures containing native Siletz River sediment.  In a subsequent 45 day trial, no statistical differences in negative growth were detected among contaminated and non-contaminated reference sediments from Port of Portland.   Other effects upon development and physiological functions will include instances of metamorphosis via chemical induction and a comparison of Na⁺ K⁺ Gill ATPase activity as an indicator of smoltification.   The second project investigates whether there is a link between herbicide exposure and lamprey’s ability to orient to biologically relevant pheromones.  These pheromones are recognized for their role as important reproductive cues during migration and spawning.   The effects of herbicides on adult lamprey will be measured using three biomarkers; a behavioral test and two physiology tests.  The behavioral test will examine whether herbicides alter lamprey’s ability to orient towards these pheromone.  We have found that adult Pacific lamprey will orient towards pheromone produced by other adults in a y-maze.  Hence, we have found this test holds promise to discern herbicide effects.  The physiological tests will examine herbicides effects on the olfactory organ.  We will also present data from experiments that examine herbicides effects on thresholds of pheromone detection using a heart rate experiment and secondly we will use a competitive displacement assays to establish if olfactory receptors are impaired by herbicides.