Biomonitoring 3.0: Beyond Taxa Lists to Evidence-Tiered Monitoring of Ecosystem Dynamics and Interactions.

High-throughput sequencing has transformed biomonitoring by enabling scalable molecular inventories, but most programs still emphasize taxa lists. In this Perspective, Biomonitoring 3.0 is proposed as a framework that builds on molecular inventories to monitor ecological dynamics, interactions, and biological responses through time. Environmental RNA is presented as a complementary source of information because, in some settings, it can provide more temporally local evidence of recent biological activity and responses than DNA alone. An inference ladder is introduced to grade interaction evidence from co-detection and statistical associations to interaction-explicit links, coupled signal-response dynamics and, where feasible, ecosystem-level consequences. Field designs are outlined that use repeated time-series sampling and paired sampling of potential signal sources and recipients to improve temporal interpretation and strengthen attribution. Minimum reporting elements are also recommended to support transparent comparison, validation, and cross-study synthesis. The "3.0" designation therefore refers to a change in the primary monitoring objective: from documenting community membership alone to evaluating ecological dynamics and feedbacks relevant to ecosystem condition and management. We conclude with a practical agenda for developing environmental nucleic-acid measurements into decision-relevant indicators of interactions and change.