Effects of environmentally relevant concentrations of nonylphenol on growth and 20-hydroxyecdysone levels in mysid crustacean, Americamysis bahia

We investigated the effects of environmentally relevant concentrations of nonylphenol (NP) on survival, growth, sexual development and molting of the mysid Americamysis bahia (Crustacea: Mysidacea), including assay of 20-hydroxyecdysone (20E) levels. Seven-day-old mysids were exposed to NP concentrations of 0.3, 1, 3, 10 and 30 µg/L for 14 days. Among growth-related traits we assayed, an effect on body length was the most prominent, with the effects observed at concentrations as low as 1 µg/L NP. In addition, the total number of molting exposed to NP for 14 days was significantly decreased in the treatment groups at 10 or 30 µg/L relative to the controls. These results clearly indicate that subchronic exposure to environmentally relevant concentrations of NP affects growth of mysids. Furthermore, we investigated the effect of NP on production of 20E in female mysids during the molting period. Production of 20E in pre-molting mysids exposed to 30 µg/L of NP was lower than those in control groups, and exposure of female mysids to NP disrupted molting cycles. Taken together, the results suggest that environmentally relevant concentrations of NP can disrupt growth of A. bahia via inhibition of 20E levels and an associated delay in molting.