Chronic effects of the strobilurin fungicide azoxystrobin in the leaf shredder Gammarus fossarum (Crustacea; Amphipoda) via two effect pathways

Fungicides pose a risk for crustacean leaf shredders serving as key-stone species litter breakdown in detritus-based stream ecosystems. However, little is known about the impact of strobilurin fungicides on shredders, even though they are presumed to be most hazardous fungicide class aquafauna. Therefore, we assessed azoxystrobin (AZO) survival, energy processing (leaf consumption and feces production), somatic growth (growth rate molting activity), reserves (neutral lipid fatty amino acids) amphipod Gammarus fossarum via waterborne exposure food quality-mediated (through colonizing aquatic microorganisms) thus indirect effects using 2 × 2-factorial experiments over 24 days. In first bioassay with 30 µg AZO/L, substantially reduced affected activity gammarids, while no were observed dietary pathway. Furthermore, negative (indicating body mass loss gammarids) was induced by exposure, which cannot explained neutral acids. These increased indicating disruption metabolism G. caused AZO. Contrary bioassay, AZO during second experiment 15 AZO/L. an altered determined gammarids fed leaves microbially colonized presence AZO, probably fungicide-induced microbial decomposition efficiency ultimately resulting lower quality. The results present study show that diet-related can occur at concentrations below those inducing toxicity. latter seems more relevant higher concentrations. • azoxystrobin/L induces 50% mortality exposure. Azoxystrobin acts metabolic disruptor. Diet-related low levels.