eDNA-based approaches advance ecotoxicology: Insights and best practices from eDNA metabarcoding studies in evaluating stress-induced aquatic (macro-) invertebrate community composition

• Water quality assessments are often based on macroinvertebrate observations. • Few ecotoxicology studies apply eDNA-methods for community assessment. • eDNA is a sensitive and robust tool for macroinvertebrate community assessment. • Despite inconsistent methods, eDNA yields consistent community data. • We propose a minimum reporting and best practice guide for improved reproducibility. Aquatic ecosystems are confronted with increasing levels of anthropogenic stress, prompting the need for rapid and reliable biomonitoring methods to allow ecological risk assessment and start science-based mitigation activities. Morphology-based sampling techniques have been the cornerstone of such evaluations and can be utilized to assess the impacts of anthropogenic stress on aquatic systems. However, environmental DNA (eDNA) has emerged as a promising alternative tool for biomonitoring. Macroinvertebrate species observations are pivotal in ecotoxicological studies and water quality assessment, nonetheless, few studies have implemented eDNA methods for stress-induced macroinvertebrate community composition assessment. To this end, we performed a systematic literature review, focusing on studies that analyzed the effects of anthropogenic stressors on macroinvertebrate community composition through eDNA metabarcoding. Our study aimed to 1) assess the relation between eDNA and morphology-based data for the assessment of stress-induced macroinvertebrate community composition; 2) evaluate the current quality of stress-induced macroinvertebrate community composition eDNA studies, and 3) formulate a minimum reporting and best practices guide for future studies. Our findings reveal that eDNA-derived beta diversity serves as a robust and sensitive indicator, outperforming morphology-based observations for determining beta diversity, making it a strong tool for invertebrate community assessment within ecotoxicology. However, we observed little consistency in applied methodology and reporting among the included studies, even though standardization is desired to increase the reproducibility and reliability of scientific research. To this end, we propose minimum reporting standards and a best practice guide for future studies, which will allow a wider and more systematic integration of eDNA metabarcoding to assess stress-induced (macro-) invertebrate community composition.