Effects of pentachlorophenol on invertebrates and fish in outdoor experimental channels

Abstract

Pentachlorophenol (PCP) was selected to assess the applicability of a toxicant criterion concentration for protecting aquatic communities in outdoor experimental channels. The criterion concentration was derived from on site laboratory bioassays. In 1982 three channels were continuously dosed with PCP for 12 wk at nominal concentrations of 48 μg/l (low, criterion level), 144 μg/l (medium, 3 × criterion) and 432 μg/l (high, 9 × criterion). In 1983 the low and medium treatments were repeated for 12 wk. Each year an untreated channel served as control. Invertebrate responses measured were changes in density, community composition and drift; fish responses were changes in survival, growth, reproduction and larval drift. Some ecosystem effects were detected at all treatment levels with fish being the most sensitive animals. Microinvertebrate densities were lower in the medium PCP channel than the control. Survival of the snail Physa gyrina was substantially reduced in the high treatment channel; no other macroinvertebrates were adversely affected by the toxicant. All fathead minnows and bluegill sunfish stocked in the high treatment channel died within the first 8 days of dosing. Fish survival was similar in all remaining channels. Fish growth and larval drift were lower in the treated channels than in the control channels and spawning was reduced in the medium dose channels. The numbers of fathead minnows collected both years from the medium dose channels were lower than the criterion and control channels. Highest numbers of bluegills were recovered from the control channels. The study indicated that the criterion concentration derived from laboratory tests did not fully protect the animals in the experimental channels.