Aqueous Leachate from Western Red Cedar: Effects on Some Aquatic Organisms

Abstract

Water-soluble extractives from western red cedar heartwood, bark, and foliage were investigated for their toxicity to aquatic organisms. The heartwood lignans and bark extractives were found to be moderately toxic, but the foliage terpenes and heartwood tropolones were more toxic, causing 50% mortality to coho salmon (Oncorhynchus kisutch) fry at 0.33 and 2.7 mg/liter, respectively. Tropolones were significantly less toxic to invertebrates than to free-swimming stages of the fish tested. Fry were found to be the stage of development of coho salmon (O. kisutch) most sensitive to the tropolones, and eyed eggs the least sensitive. Sensitivity of the coho fry to tropolones was moderated by previous sublethal exposure or the presence of a chelatable cation. Results from field studies and a leaching study indicate that directly releasing cedar leachate from landfills or allowing logging debris to enter streams should be avoided.