Effects of nitrate on early life stages of Astacus astacus (Linnaeus, 1758) and Procambarus virginalis (Lyko, 2017)

We examined the effects of nitrate on the embryonic development of two freshwater crayfish species, the indigenous noble crayfish (Astacus astacus) and the invasive marbled crayfish (Procambarus virginalis). Nitrate measurements show concentrations of 50 mg/L in surface waters of Germany, while concentrations in groundwater measure up to 100 mg/L. Performing a chronic exposure experiment, we exposed embryos of both species to nitrate concentrations of between 0.0 mg/L and 500 mg/L to estimate the influences of nitrate concentrations on survival, hatching development time, malformations and growth. We observed the first effects on survival at 14 mg/L LOEC (lowest observed effective concentration) nitrate for marbled crayfish. For noble crayfish, we estimated an EC50 value of 55.7 mg/L on hatching rate. Our results show that eutrophication of surface waters can negatively affect the embryonic development of freshwater crayfish with serious consequences on recruitment.