Crawling towards complex interactions: the impact of 6PPD-quinone and increased temperatures on the freshwater snail Ampullaceana balthica

N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-quinone or 6PPDQ) is an oxidation product of 6PPD, an antioxidant used in tyres to prevent rubber degradation, that has been associated with high mortality in juvenile coho salmon at concentrations as low as 95 ng/L. While research has focused primarily on fish, the effects of 6PPDQ on freshwater invertebrates remain limited. In this study, we assessed the toxicological impact of this contaminant on the freshwater snail Ampullaceana balthica over a 10-day experiment under two different temperature conditions. A. balthica was chosen because it is widely distributed in temperate and Mediterranean regions and is commonly used as a model organism in environmental toxicology studies. Although 6PPDQ had a limited impact on embryonic development, adult snails experienced significant effects on reproduction, growth, and motility, with more pronounced impacts at higher temperatures. Specifically, 6PPDQ reduced clutch and egg production, particularly during the first days of exposure. Elevated temperature increased reproduction, but its interaction with 6PPDQ lowered the overall reproductive output. The combined stressors also impaired growth and motility. Development was mainly affected by temperature, with reduced hatching and increased embryo arrest at 20°C. These sublethal effects may lead to population declines and cascading impacts on freshwater community structure and ecosystem functioning, particularly under climate change scenarios. This highlights the urgent need for comprehensive risk assessments of emerging contaminants such as 6PPDQ to better understand their ecological impacts.