Carboxylic acid-induced freshwater acidification effects on behavior and operculum ultrastructure in the gastropod mollusc Bellamya bengalensis

Abstract

ABSTRACT Global freshwater acidification, accelerated by rising pCO2, remains a critical ecological concern. Despite the prevalence of carboxylic acids like acetic acid (AA) and benzoic acid (BA) in freshwater, their potential to exacerbate acidification and impact biota is not fully understood. In this study, we examined behavioural disruptions during acute exposures (96 h) and operculum ultrastructure changes during chronic exposures (28 days) to ecologically-relevant concentrations of AA (39.7, 79.5, and 99.4 mg/L) and BA (31.4, 62.8, and 78.5 mg/L) in Bellamya bengalensis. Acute exposures revealed significant behavioural disruption, including reduced activity and impaired escape behaviour. Chronic exposures led to ultrastructural defects in the operculum, with more pronounced effects in BA-exposed groups. Acidification scenarios appeared to impact calcium carbonate crystal formation, compromising opercula structure. Our study underscores the importance of understanding both acute and chronic effects of freshwater acidification on molluscan species, emphasising the need for further research into the underlying mechanisms and thresholds of acidification tolerance.