Molecules, microbes, and function: synchronizing depth-resolved molecular and microbial time series at BATS.

The marine dissolved organic matter (DOM) pool is one of Earth's largest carbon reservoirs and a critical regulator of global carbon flux, yet the microbe-molecule interactions governing it remain largely unresolved. In a significant advancement, McParland and colleagues integrate a 3-year, depth-resolved molecular time series of DOM with parallel taxonomic characterization of prokaryoplankton at the Bermuda Atlantic Time-series Study site to examine the coupling between community composition and DOM molecules (E. L. McParland, F. Wittmers, L. M. Bolaños, C. A. Carlson, et al., mSystems 11:e01540-25, 2026, https://doi.org/10.1128/msystems.01540-25). Their analysis reveals high temporal coordination, with approximately 40% of both DOM molecules and microbial taxa exhibiting 12-month periodicities. However, interannual patterns in DOM composition appear more predictable than that of microbial communities, suggesting that functional redundancy, conferred through core metabolic pathways shared across taxa, may act as a stabilizing force for ocean chemistry. By highlighting the endurance of these functional roles, McParland and colleagues provide a framework for incorporating microbial processes into more mechanistic and predictable biogeochemical models.