Effects of Pentachlorophenol on the Meiobenthic Nematodes in an Experimental System

Abstract

Aquaria containing clean sand received a continuous supply of seawater from Santa Rosa Sound, Florida, mixed with known quantities of PCP for nine weeks (May 10 — July 12, 1976) for the first experiment and Dowicide® G-ST for thirteen weeks (December 27, 1976 — March 28, 1977) for the second experiment. The measured concentrations of PCP in the former experiment were 7, 76 and 622 μ while the concentrations of 1.8, 15.8 and 161 μ/l were used in the latter experiment. At the end of each experiment the meiofauna established in the control and experimental aquaria were examined. Nematodes were the dominant group and averaged 83% of all the meiofauna encountered. Concentrations of 1.8, 7 and 15.8 μg PCP/1 did not affect the biomass and density of nematodes. An intermediate concentration of PCP (76 μg/1) caused an increase in biomass and density of nematodes compared to control aquaria. Higher concentrations of PCP (161 and 622 μ1/) caused a decrease in biomass and density of nematodes compared to control aquaria. Marked changes in nematode species composition and shifts in nematode feeding types were noticed in the aquaria exposed to 161 and 622 μg PCP/1. Nematodes classified as epistrate feeders were most abundant in the control aquaria and those exposed to 1.8, 7, 15.8 and 76 μg PCP/1. Deposit feeders were relatively abundant among the nematodes in aquaria exposed to 161 and 622 μg PCP/1. The alterations in nematodes observed in this investigation appeared to be due to the variations in macrobenthic fauna and food (algae) supply caused by the biocidal effects of PCP and also due to the toxic effects of PCP on meiofauna.