Effects of Wastewater Treatment Plant Effluent on Survival, Growth, and Vitellogenin Concentrations of Fathead Minnows (Pimephales promelas)

Abstract

Concern over pharmaceuticals and personal care products (PPCPs) in surface waters has increased as scientists have detected these contaminants in streams and rivers nationwide. One source of PPCPs is wastewater treatment plants (WWTPs), where some PPCPs are being deliveredand then discharged to receiving waters in effluent.  Estrogens, the primary female sex hormones, have been found in natural and synthetic forms in effluent and in receiving waters. Field and laboratory studies were carried out to determine if a local WWTP’s effluent affects survival, egg production, and vitellogenin (an egg precursor protein) concentrations in fathead minnows.  Results from a 24-day field study showed no significant difference in survival or egg production between fish caged at sites located upstream and downstream of the WWTP effluent pipe. Vitellogenin was detected in some male fish at both sites. A comparison of male fish that produced vitellogenin showed higher concentrations in those located downstream. Because there may be other sources of estrogens or estrogen mimics to the stream, acute and chronic whole effluent toxicity (WET) tests were conducted with larval fathead minnows, and a reproduction assay was conducted with adult fathead minnows in the laboratory. Results of the WET tests showed no significant difference in survival among fish exposed to different dilutions of whole effluent. The laboratory reproduction assay showed no significant differences in survival or egg production between fish in 100% effluent and control treatments. Vitellogenin was detected in all male fish analyzed, including controls. This indicates there may be other sources of estrogenic compounds in the laboratory as well. While biomarkers such as vitellogenin may be more sensitive than other endpoints, it is important to have a good understanding of their selectivity.  Combining field and laboratory studies can provide a better understanding of the potential effects of WWTP effluent on aquatic organisms.