title: Latent Toxicity of Endothall to Anadromous Salmonids During Seawater Challenge.
abstract: Limited evidence exists on the latent effects of toxicant exposure on the seawater adaptability of anadromous salmon and steelhead. It is unclear whether such an effect exists for the widely used and relatively non-toxic herbicide endothall. Coho salmon, Oncorhynchus kisutch (coho), Chinook salmon, O. tshawytscha (Chinook), and anadromous rainbow trout, O. mykiss (steelhead) were subjected to a 10-day seawater challenge following freshwater treatments [0-12 mg acid equivalent (a.e)./L at 96 h]. Mean survival resulted in 82 % (n = 225), 84 % (n = 133), 90 % (n = 73) and 59 % (n = 147) survival for 0, 3-5, 6-8, and 9-12 mg a.e./L, respectively. Our results indicate a lower toxicity threshold compared with previously reported acute toxicity results, but higher compared with previous seawater challenge studies. We demonstrate the utility of the seawater challenge assay to accurately define toxic effects of pesticides on salmonids with complex life-histories.
authors.affiliation: Mount Hood Environmental, PO Box 744, Boring, OR, 97009, USA. lauren.courter@mthoodenvironmental.com.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Courter
authors.affiliation: Cramer Fish Sciences, 600 NW Fariss Road, Gresham, OR, 97030, USA.|Fish Passage Center, 847 NE 19th Avenue Suite 250, Portland, OR, 97232, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Garrison
authors.affiliation: Cramer Fish Sciences, 600 NW Fariss Road, Gresham, OR, 97030, USA.|Mount Hood Environmental, PO Box 744, Boring, OR, 97009, USA.
authors.forename: Ian I
authors.initials: II
authors.lastname: Courter
mesh_terms: D000818:Animals; D003998:Dicarboxylic Acids / Q000633:toxicity*; D004781:Environmental Exposure; D005618:Fresh Water; D017683:Oncorhynchus / Q000502:physiology*; D017686:Oncorhynchus mykiss; D010575:Pesticides / Q000633:toxicity*; D012623:Seawater / Q000737:chemistry*; D016019:Survival Analysis; D023382:Toxicity Tests, Acute
chemical_list: D003998:Dicarboxylic Acids; D010575:Pesticides; C100030:endothall
keywords: Endothall; Herbicide; Latent lethality; Salmonids; Seawater challenge