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 6PPD-Q) is an oxidation product of 6PPD, an antioxidant used in tires to prevent rubber degradation, that has been associated with high mortality in juvenile coho salmon at concentrations as low as 95 ngL⁻¹. While research has focused primarily on fish, the effects of 6PPD-Q 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 6PPD-Q had a limited impact on embryonic hatching, adult snails experienced significant effects on reproduction, growth, and motility, with more pronounced impacts at higher temperatures. Specifically, 6PPD-Q reduced clutch and egg production, particularly during the first days of exposure. Elevated temperature increased reproduction, but its interaction with 6PPD-Q lowered the overall reproductive output. The combined stressors also impaired growth, motility and embryo development. 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 6PPD-Q to better understand their ecological impacts. First evidence of sublethal 6PPD-Q effects on molluscs at environmental levels. Repeated 6PPD-Q exposure impaired reproduction, growth, motility and embryo development in Ampullaceana balthica. High temperatures increased egg production, but 6PPD-Q reduced reproductive output. Growth rates declined with combined exposure to high temperatures and 6PPD-Q.