Individual and mixture effects of selected pharmaceuticals on larval development of the estuarine shrimp Palaemon longirostris

- Chronic toxicity of clofibric acid (CA) may depend mainly on the duration of exposure.
- Multiple stressor effects of CA in intermoult and duration of larval development
- Low salinity reduced larval tolerance to sublethal concentrations of CA.
- Similar effect of the mixture diclofenac sodium and CA as compared with CA in isolation
- Interspecific variations of CA on development and growth of the two Palaemon species

Few ecotoxicological studies incorporate within the experimental design environmental variability and mixture effects when assessing the impact of pollutants on organisms. We have studied the combined effects of selected pharmaceutical compounds and environmental variability in terms of salinity and temperature on survival, development and body mass of larvae of the estuarine shrimp Palaemon longirostris. Drug residues found in coastal waters occur as mixture, and the evaluation of combined effects of simultaneously occurring compounds is indispensable for their environmental risk assessment. All larval stages of P. longirostris were exposed to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DS: 40 and 750 μg L− 1), the lipid regulator clofibric acid (CA: 17 and 361 μg L− 1) and the fungicide clotrimazole (CLZ: 0.14 and 4 μg L− 1). We observed no effect on larval survival of P. longirostris with the tested pharmaceuticals. However, and in contrast to previous studies on larvae of the related marine species Palaemon serratus, CA affected development through an increase in intermoult duration and reduced growth without affecting larval body mass. These developmental effects in P. longirostris larvae were similar to those observed in the mixture of DS and CA confirming the toxic effects of CA. In the case of CLZ, its effects were similar to those observed previously in P. serratus: high doses affected development altering intermoult duration, tended to reduce the number of larval instars and decreased significantly the growth rate. This study suggests that an inter-specific life histories approach should be taken into account to assess the effect of emergent compounds in coastal waters.