Comparison of two sentinel species <i>Gammarus fossarum</i> and <i>Dreissena polymorpha</i> for monitoring fecal viral contamination of continental waters

Biomonitoring is a common method for assessing chemical contamination. In France, <i>Dreissena polymorpha</i> (zebra mussel) and <i>Gammarus fossarum</i> (a freshwater crustacean) are widely used species. This study aimed to compare, for the first time, their effectiveness in monitoring viral contamination, specifically F-specific RNA bacteriophages (FRNAPH) and noroviruses. Laboratory experiments showed that <i>D. polymorpha</i> accumulated six times more infectious FRNAPH than <i>G. fossarum</i>. Field exposures confirmed these findings, revealing that only mussels accumulated detectable levels of FRNAPH and norovirus genomes. Additionally, the viral concentrations in <i>D. polymorpha</i> reflected a gradient of fecal contamination across sites. These results demonstrate that <i>D. polymorpha</i> is significantly more effective than <i>G. fossarum</i> for monitoring viral contamination of fecal origin in freshwater environments, making it the more suitable species for such biomonitoring efforts.