Effects of sodium fluoride on the gametogenesis of the tubificid oligochaete Branchiura sowerbyi Beddard

Abstract

Fluoride concentration is significantly increasing in many aquatic ecosystems because of human activities (agrochemical, pharmaceutical, refrigerant, pesticide and surfactant compounds). This study aims to examine the effects of fluorides on gametogenesis by exposing Branchiura sowerbyi (Oligochaeta) to sodium fluoride concentrations 50 to 100 times above normal ones in freshwater (0.1–0.3 mg/L) and observing the effects over time. Because non-toxic concentrations determined in short-term experiments could induce effects as exposure times increase, B. sowerbyi were exposed to sodium fluoride from the end of February 2012 to the end of July 2012. They were continuously monitored until the cocoon deposition stage to investigate any possible effects. Weekly observations were conducted on treated and untreated specimens to monitor gamete maturation in both male and female germinal lines. The results revealed temporal differences in the gametogenesis phases of treated specimens, such as incomplete spermatozoa maturation. At the end of the experiment, the exposed animals were thinner and shorter than the controls and cocoon deposition did not occur.