Acute toxicity and sublethal behavioral effects of copper on barnacle nauplii (Balanus improvisus)

This study documents the effects of short-term (24 h) sublethal copper exposures on undirected swimming activity and photobehavior of B. improvisus stage II nauplii. All Cu treatments were static, with temperature and salinity conditions at 20 degree C and 15 or 30ppt. The 24 h LC sub(50) estimate for Cu is 88 ppb at 15ppt. and > 200 ppb at 30ppt. Sub-lethal Cu concentrations cause reductions in swimming speed, which decrease progressively with increasing Cu dose. At 50 ppb Cu, this was significant primarily at light intensities below the phototactic threshold. At higher Cu concentrations, significant reductions in mean linear velocity occurred at most light intensities tested. At 30ppt., 50 and 100 ppb Cu also reduce the positive photatactic response and 150 ppb Cu causes reversal of phototaxis at optimal intensities. Swimming speed and photobehavior show promise as sensitive behavioral indicators of copper toxicity.