Copper barriers can cause behavioral artifacts in experiments with marine snails

Abstract

Many gastropod species will not cross copper barriers; thus, copper has been used to manipulate their movements and minimize caging artifacts. However, as the reason for copper barrier avoidance is unknown, it is difficult to predict experimental artifacts that might result from its use. Copper can be toxic to gastropods, resulting in behavioral alterations or death, but there is little evidence copper barriers can cause these effects. In this study, we assessed whether copper mobilizes from copper barriers in water and alters gastropod behavior, using periwinkle snails Littoraria irrorata. Snails were placed in containers with and without copper tape and in copper solutions (0, 0.1, 0.2, 1.0, and 2.0 ppm) created by soaking copper tape in seawater. We measured the number of snails that climbed out of the water and the ability of snails to emerge and right themselves. Snails in 1.0, 2.0 ppm, and copper tape treatments were immobilized and did not climb out of the water or emerge from their shells. Snails in lower concentrations were more likely to climb out of the water. Low copper concentrations also reduced the number of snails emerging and righting, but those that did emerge did so in less time. When exposed snails were moved to clean water, snails previously immobilized by copper were quicker to crawl out of the water. Our results demonstrate that copper can mobilize from copper barriers resulting in alterations to snail behavior. To avoid experimental artifacts, we suggest the use of copper barriers be avoided in future experiments.