Locomotor behavior of four marine teleosts in response to sublethal copper exposure

Abstract

In order to examine the effects of sublethal Cu 2+ (0.1 mg · l −1) exposure on pinfish, ( Lagodon rhomboides), Atlantic croaker ( Micropogon undulatus), sheepshead ( Archosargus probatocephalus) and sea catfish ( Arius felis) locomotor behavior, the movements of individual fish were electronically monitored in 16-choice circular tanks, before and after 72 h of exposure. Confinement in exposure tanks without the addition of Cu 2+ did not affect the behavior of a separate control group of sea catfish. Behavioral variables (general activity, swimming speeds and angular orientation of movements), previously shown to be statistically autonomous and presumed to be controlled by separate (neuro-) physiological mechanisms, were affected by Cu 2+ exposure in different ways in each species. Immediately after exposure sheepshead and sea catfish were hyperactive while the pinfish and 33% of the croaker became hypoactive. The orientation angles of movements through the tanks increased in the croaker and sea catfish and decreased in the sheepshead, while pinfish showed intermediate changes. Two weeks after exposure the sheepshead resumed normal (pre-exposure) activity, swimming speed and decreased the initial angular orientation. Sea catfish on the other hand became extremely hypoactive, decreasing their swimming speed and increasing their angular orientation. More than 60% of the sea catfish died between 1 and 3 wk after exposure, suggesting a latent effect from the Cu 2+ exposure. No mortality occurred in the other species. Several possible physiological reactions due to Cu 2+ exposure are discussed, which may account for different susceptibilities and behavioral changes between the species.