Effects of Heavy Metal Pollution on the Antipredator Behavior of Orangethroat Darters (Etheostoma spectabile)

Heavy metal pollution can have numerous negative impacts on stream fishes, including both lethal and sublethal effects. Because of the sensitivity of fishes to toxins, they are excellent environmental indicators of stream and watershed health. The Tri-State Mining District is a Superfund site located in parts of Missouri, Kansas and Oklahoma that offers a good opportunity to study sublethal effects of heavy metal pollutants on fish behavior. I observed the antipredator behavior of Orangethroat Darters (Etheostoma spectabile) from 3 streams that varied in the abundance of heavy metal pollutants. In the lab, darters from the most polluted site were less active overall, but darters from both polluted sites produced alarm cues and responded to the cues with an appropriate fright response. In field trials, I observed darters by snorkeling and recording how darters from each stream responded to the threat of an approaching predator. Darters from heavily and moderately polluted streams showed a reduced tendency to flee, relative to uncontaminated stream darters when approached by a predator. Therefore, long-term exposure to heavy metals from mining pollution is associated with changes in behavior of stream fishes.