The Effects of Pharmaceutical and Estrone Exposure on Predator Avoidance Performance and Feeding Efficiency in Larval Fathead Minnows

With the increased use of pharmaceuticals and endocrine active compounds, more of these chemical compounds are reaching the aquatic environment. Some pharmaceuticals and endocrine active compounds have reported effects concentrations in the nanogram per liter range. However, few experiments have examined the effects of these compounds on larval fish behavior. For the current study, fathead minnows (Pimephales promelas) were exposed to either an ethanol solvent control, diclofenac (1,600 ng L-1), methocarbamol (4,800 ng L-1), rosuvastatin (3,200 ng L-1), sulfamethoxazole (2,200 ng L-1), temazepam (1,600 ng L-1), estrone (E1) at 125 ng L-1 or 625 ng L-1 for twenty-one days in a 50% daily static renewal system. The exposure began three days after fertilization of eggs when eye spots were observed. Following the twenty-one days of exposure, the larvae were subjected to a predator avoidance test to examine whether the pharmaceutical or E1 exposures caused a deficiency in the predator avoidance performance. Larvae exposed to rosuvastatin, diclofenac or 125 ng L-1 E1 exhibited a delayed latency period during the predator avoidance performance (p\u3c0.05). A feeding efficiency test was also conducted to determine the effects of exposure on a larvae’s ability to forage. Only larvae exposed to E1 (125 ng L-1) showed deficiencies in the percentage of brine shrimp consumed. By examining a larvae’s ability to effectively escape predation and to feed efficiently, two main aspects of evolutionary fitness were assessed. Our experiments demonstrated that both pharmaceuticals and E1 can diminish these behaviors. As a consequence, fish may fail to reach maturity, resulting in subsequent loss of reproduction with unknown population level consequences