Exposure to textile microfibers causes no effect on blood, behavior and tissue morphology in the three-spined stickleback (Gasterosteus aculeatus)

We assessed textile microfibers impacts on the three-spined stickleback, using synthetic and natural fibers originating from yarns or washer effluents. After water exposure at 200 fibers/L, we assessed fish survival, behavior, tissue morphology and hemoglobin concentration, and paid special attention to exposure characterization. We report quantitative fiber distribution in the exposure system, fiber size distribution, and contamination. We provide a fiber preparation procedure and exposure method intended to ensure accurate and stable concentrations over time. Following exposure, no effect was observed on the studied endpoints in any of the treatment conditions. We observed fast sinking of the fibers. Fish organs and feces contained 1.3% and 6.8% of recovered fibers, and 12.6% fibers were found adhered to the tank walls. We show that water renewals in semi-static exposures is a critical step for the maintenance of stable concentrations, and discuss the practical and/or methodological challenges associated to the study of microfibers. [Display omitted] •Water exposure to microfibers at environmental concentrations do not affect fish.•No difference was observed between natural and synthetic microfibers.•Microfibers quickly sink and are mostly found at the bottom of the water column.•Fibers are found in fish gills, gut and feces, and adhered to tank walls.•We describe fiber preparation and exposure methods for accurate, stable concentrations.