Adverse effect of antifouling compounds on the reproductive mechanisms of the ascidian Ciona intestinalis.

Alessandra Gallo,Elisabetta Tosti

doi:10.3390/md11093554

Abstract

Fertilization and embryo development that occur in sea water are sensitive to xenobiotics from anthropogenic sources. In this work, we evaluated the influence of two antifouling biocides, tributyltin (TBT) and diuron, on the reproductive mechanisms of the marine invertebrate Ciona intestinalis. By using electrophysiological techniques, we examined the impact of these compounds on the electrical properties of the mature oocytes and of events occurring at fertilization. With different toxicity assays, we studied the effect of the two biocides on the gametes by evaluating fertilization rate and embryo development. Results show that sodium (Na+) currents were significantly reduced by either of the two biocides, whereas conductance was significantly increased. The fertilization current frequency and amplitude, fertilization rate and larval development were affected only by TBT. This study suggests that: (i) the two biocides affect either the electrical properties of the oocyte plasma membrane and the reproductive success representing a risk factor for the survival of the species exposed to environmental pollution; (ii) the ascidian Ciona intestinalis may represent a good model organism to test toxicity of marine pollutants. Possible mechanisms of action of the two biocides are discussed.

Highlights

Environmental pollution represents a serious hazard for terrestrial and aquatic ecosystems and may result in significant ecotoxicological effects
We have shown an impact of two antifouling biocides on the physiology of the oocyte and subsequent fertilization process of the marine invertebrate C. intestinalis
We demonstrated that some ascidian reproductive mechanisms are sensitive to antifouling compounds

Summary

Introduction

Environmental pollution represents a serious hazard for terrestrial and aquatic ecosystems and may result in significant ecotoxicological effects. Diverse substances have been released into marine environment as a consequence of agricultural production, manufacturing processes and their by-products. These chemicals include herbicides, pesticides, fungicides, plasticizers, antifoulants and others [1]. Several studies report the diffusion of female marine snails with male genitalia, including a penis and vas deferens [8,9,10] This phenomenon, known as imposex, appears to be an irreversible induction of male sex characteristics on females and was proved to be caused mainly by exposure to tributyltin (TBT) compounds [11,12]. A specific toxic effect of TBT has been reported on cell membranes of mitochondria and erythrocytes [14,15]

Results

Discussion

Conclusion