Oxidative stress and physiological impacts of microplastic and elevated temperatures on Odontesthes argentinensis larvae

Plastics are ubiquitous in the environment, widely used in diverse industrial applications, yet they pose escalating environmental challenges due to their persistence and bioaccumulative potential as microplastics (MP). Alongside this, the average global temperature increase represents an additional physiological stressor for many species. This study investigated the bioaccumulation and physiological impacts of polystyrene MP (spherical, 1.1 µm) on Odontesthes argentinensis larvae under two distinct temperatures (22 and 26 ºC). Larvae were exposed to MP concentrations of 40 and 400 µg/L for 96 h, with a control group maintained under identical conditions without MP exposure. Our findings revealed MP bioaccumulation in larval tissues, along with significant biochemical effects: reduced superoxide dismutase (SOD) activity, increased catalase (CAT) and glutathione S-transferase (GST) activities, particularly at higher temperatures, as well as elevated lipid peroxidation levels and reduced growth. These results underscore the susceptibility of O. argentinensis larvae to MP exposure and elevated temperatures, reflecting projected climate scenarios that may compromise the species' ecological success and cause socioeconomic harm to communities reliant on fishing.