Immunotoxicity of Municipal Effluents to Freshwater Mussels

Gagne F,Cejka P,André C

doi:10.4172/2161-0525.1000104

Abstract

The release of treated municipal wastewaters to the aquatic environment raises concern about the health impacts on local resident invertebrates such as mussels. The purpose of this study was to examine the immunotoxicity of two types of treated municipal effluents—physico-chemical treated and physico-chemical with additional ozonation—to freshwater mussels. Immunocompetence was followed by tracking changes in hemocyte viability, adherence, phagocytosis, vitellogenin (Vtg)-like proteins and the pro-inflammatory precursors nitric oxide (NOx) production and arachidonate cyclo-oxygenase (COX) activity. The study results revealed that following a two-week continuous-flow exposure to the effluents, a reduction in hemocyte viability, adherence, NOx and COX activities was observed. Vtg like proteins were also increased, highlighting the estrogenic nature of the effluents. A significant correlation was found between Vtg-like proteins and the phagocytic efficiency index (r=0.34; p<0.001), which suggests that estrogenic compounds may have been involved in the immunocompetence of mussels exposed to municipal effluents. In conclusion, short-term exposures to treated municipal effluents have the potential to impede the immunocompetence of mussels occurring in the vicinity of an effluent dispersion plume.

Highlights

Municipal effluents are well known to be major sources of contamination in aquatic ecosystems
Final gamete maturation and spawning depends on both serotonin and prostaglandin signalling, two processes that could be influenced by anti-depressive and non-steroidal anti-inflammatory drugs
The presence of anti-infectives and selective reuptake inhibitors were found in this effluent indicating the release of pharmaceutical products from human therapeutic use [21,22] Municipal effluents are well known to influence the immune system in both marine and freshwater mussels [14, 23]

Summary

Introduction

Municipal effluents are well known to be major sources of contamination in aquatic ecosystems. In addition to the heavy metals and polyaromatic hydrocarbons they contain, some of the urban contaminants in municipal effluents exhibit neuroendocrinedisrupting activity such as 17α-,17β-ethynylestradiol (active ingredient in birth control pills), nonylphenol (a breakdown product of alkylphenol polyethoxylate surfactants), bisphenol A and the natural estrogen 17β-estradiol [1,2,3]. The freshwater mussel is a key member of the benthic community in many aquatic habitats worldwide Because these mussels are sedentary filter-feeders, they are at risk to continuous sources of pollution such as municipal effluents. Vtg possesses bactericidal and opsonising activity and helps immunocytes to inactivate bacteria in fish [12]

Objectives

Methods

Results

Conclusion