Multiple stressor effects of insecticide exposure and increased fine sediment deposition on the gene expression profiles of two freshwater invertebrate species

Abstract

Background Freshwater ecosystem degradation and biodiversity decline are strongly associated with intensive agricultural practices. Simultaneously occurring agricultural stressors can interact in complex ways, preventing an accurate prediction of their combined effects on aquatic biota. Here, we address the limited mechanistic understanding of multiple stressor effects of two globally important stressors, an insecticide (chlorantraniliprole), and increased fine sediment load and assessed their impact on the transcriptomic profile of two stream macroinvertebrates: the amphipod Gammarus pulex and the caddisfly Lepidostoma basale. Results We identified mainly antagonistic stressor interactions at the transcriptional level, presumably because the insecticide adsorbed to fine sediment particles. L. basale, which is phylogenetically more closely related to the insecticide’s target taxon Lepidoptera, exhibited strong transcriptional changes when the insecticide stressor was applied, whereas no clear response patterns were observed in the amphipod G. pulex. These differences in species vulnerability can presumably be attributed to molecular mechanisms determining the cellular affinity toward a stressor as well as differential exposure patterns resulting from varying ecological requirements between L. basale and G. pulex. Interestingly, the transcriptional response induced by insecticide exposure in L. basale was not associated with a disruption of the calcium homeostasis, which is the described mode of action for chlorantraniliprole. Instead, immune responses and alterations of the developmental program appear to play a more significant role. Conclusions Our study shows how transcriptomic data can be used to identify multiple stressor effects and to explore the molecular mechanisms underlying stressor-induced physiological responses. As such, stressor effects assessed at the molecular level can inform about modes of action of chemicals and their interplay with non-chemical stressors. We demonstrated that stressor effects vary between different organismic groups and that insecticide effects are not necessarily covered by their described mode of action, which has important implications for environmental risk assessment of insecticides in non-target organisms.

Complex compositional and cellular response of river sediment microbiomes to multiple anthropogenic stressors

“…Thus, general principles of microbial community responses to multiple stressors and their recovery after stressor release remain scarce. However, this knowledge is crucial to identify combinations of stressors that are particularly harmful for microbial biodiversity and associated ecosystem functions due to potential synergistic interactions and thus crucial for remediation of stressed ecosystems (Brasseur et al, 2023;Hawley, 2018;Liu et al, 2020).…”

“…An experimental system to test multiple stressors in full-factorial settings with high replication while still under semi-natural conditions is the ExStream system, which has been widely used in stream ecology research (Beermann et al, 2018;Brasseur et al, 2023;Elbrecht et al, 2016;Nuy et al, 2018). For instance, Nuy et al investigated the effect of multiple anthropogenic stressors on microbiota with a focus on the communities on leaf litter and biofilm tiles (Nuy et al, 2018).…”