Effects of diclofenac on the freshwater rotifer Lecane papuana (Murray, 1913) (Monogononta: Lecanidae)

Abstract

Background: The diclofenac (DCF) is a non-steroidal anti-inflammatory drug (NSAID) that has been found in groundwater and superficial water, as a result of its high consumption in animal and human health. Moreover, DCF toxicity has been studied in different fresh-water animal models and it has been shown to have harmful effects on cladocerans, fish and amphibians, but the available information is still scarce in terms of induced alterations in organisms that are the basis of trophic levels such as rotifers. Goals: The present work assessed the effect of DCF on acute and chronic responses of the freshwater rotifer Lecane papuana (Murray, 1913). Methods: Acute toxicity tests were carried out to determine the LC50 of DCF (128.82 mg/L). Then, five sublethal concentrations were selected (1/160, 1/80, 1/40 y 1/20, y 1/10 of the corresponding LC50), and a control group (reconstituted hard water), to which amictic eggs were exposed to determine the effect on hatching and neonates were exposed to evaluate the effects on further fecundity and population increase in terms of r. Results: DCF diminished the r rate through the inhibition of eggs hatching and reduced fecundity of exposed females (fewer eggs per female) at 0.80 mg/L and higher concentrations. The effective median concentrations were about 700-fold lower than the corresponding LC50. Conclusions: These results indicate that DCF can affect rotifer populations at concentrations, that despite being higher than environmental concentrations, and due to the continuous release of DCF to the aquatic systems, would eventually have a negative impact on the exposed populations.