Peter H. Johansen

Impairment of Early Feeding Behavior of Largemouth Bass by Pentachlorophenol Exposure: A Preliminary Assessment

Abstract Largemouth bass Micropterus salmoides were reared over their first 8 weeks of free-swimming life in uncontaminated control water or in water containing one of five concentrations of pentachlorophenol (PCP) ranging from 1.6 to 88 μg/L. Over the final 3 weeks of the study, fish reared in concentrations of 67 and 88 μg PCP/L performed significantly fewer feeding acts (orientations, bites) and had a lower rate of prey capture than did control fish. However, fish in high concentrations spent significantly more time swimming than did control fish, which indicated that exposure to PCP made them hyperactive. By inhibiting energy intake while inducing higher energy expenditures, PCP may reduce survival of young largemouth bass over the winter.

The growth and feeding behaviour responses of largemouth bass (Micropterus salmoides) exposed to PCP

Abstract The growth and feeding behaviour of individually held underyearling largemouth bass (Micropterus salmoides) exposed to 50 μg/l pentachlorophenol (PCP) was monitored over a 7-day period which followed a 7-day acclimation period to the experimental conditions. Exposure to PCP reduced food conversion efficiency (g of growth/g of food) by 30% as well as the amount of food consumed. Feeding efficiency (capture to strike ratio) was also lowered by PCP exposure. Our experiment not only documents growth related responses to a toxic substance but demonstrates that the effects of a toxic substance can be readily determined with a carefully executed short term experiment.

Laboratory Studies of Microhabitat Selection by the Guppy, Poecilia reticulata (Peters)

ABSTRACT In a laboratory study, guppies (Poecilia reticulata) demonstrated microhabitat selection. In general, preference was shown for shallow and air-water interface areas of a test aquarium with a V-shaped bottom. These responses are interpreted as adaptations to ecological constraints typical of guppy natural habitats. Some fish altered their preferences depending on the sex and age of other fish they were tested with. Stock members reared in waters deeper than the test apparatus showed preferences for deeper waters. These preference changes due to social and rearing conditions highlight the need for careful design and interpretation of microhabitat selection studies on this and other species.

A comparison of the effects of subchronic and spill-mimicking pentachlorophenol exposures on growth of bluegill sunfish (Lepomis macrochirus)

Abstract Bluegill sunfish ( Lepomis macrochirus ), exposed to a 22-day subchronic exposure of pentachlorophenol at concentrations of approximately 20 and 75% of the 96-h median lethal concentration (96 h LC 50 ), showed significant reductions in food conversion efficiency measured during the last 10 days of exposure. Bluegills exposed to a 3-day acute spill-mimicking exposure of pentachlorophenol at a concentration of approximately 100% of the 96 h LC 50 failed to show a significant reduction in food conversion efficiency measured during the 10 days following exposure. Bluegill sunfish exposed to pentachlorophenol at continuous low-level concentrations are at a greater risk for decreased growth than those exposed to a more concentrated short-term pulse of toxicant.

Pentachlorophenol and Reduced Food Intake of Bluegill

Abstract During the final 10 d of a 22-d subchronic exposure of bluegills Lepomis macrochirus to a pentachlorophenol (PCP) concentration of 173 μg/L, bluegill growth rate significantly decreased by 75% when compared with untreated controls, and food intake declined significantly (29%). At a PCP concentration of 48 μg/L, growth rate was significantly reduced by 26%, but food intake showed a nonsignificant decline. Pentachlorophenol-induced decreases in food intake make this species especially vulnerable to the growth-perturbing effects of the toxicant.