Além da co-ocorrência: redes ecológicas reconstruídas a partir de dinâmicas caóticas revelam padrões temporais do microbioma planctônico

Abstract

Inland waters are a central piece in the carbon cycle, linking terrestrial ecosystems and the Ocean, contributing substantially to carbon processing. Microbial communities are at the core of this large reactor, underpinning carbon transformations by routing and converting dissolved organic matter (DOM) through diverse pathways within an elaborate interaction network shaped by environmental drivers, such as the balance between allochthonous and autochthonous DOM inputs. A key mechanism in this context is the synergistic exploitation of multiple DOM pools by bacteria (priming effect), which can alter bacterial community composition, increase bacterial production, stimulate phytoplankton production and enhance the microbial food web. However, the balance between allochthonous and autochthonous carbon can be shifted by climate change altering rainfall regimes and hydrological connectivity, modifying terrestrial DOM inputs, while also promoting more frequent or intense cyanobacterial blooms that increase autochthonous DOM production. Here, we use a 5-year monthly time-series data from a tropical reservoir to reconstruct ecological networks, combining long-term, cross-domain metabarcoding community data with Empirical Dynamic Modelling (EDM), a nonlinear, data-driven analytical approach, to test whether DOM source balance influences key network properties. Our results indicate that terrestrial DOM inputs associated with hydrologic seasonality decreased connectance and promoted network specialization, whereas autochthonous, cyanobacterial bloom-associated DOM inputs were associated with a decrease in the average net strength of interactions, possibly reflecting an intensification of competitive, antagonistic, or inhibitory relationships, and/or a reduction in positive interactions associated with metabolic facilitation or trophic complementarity. Alltogether, these findings demonstrate how shifts in contrasting DOM sources reverberate through planktonic cross-domain network architecture and interaction strength, offering insights into potential DOM-related effects beyond changes in community composition. It also emphasizes that understanding carbon processing and the ecological dynamics under climate change requires approaches that explicitly capture the context-dependent, time-varying reorganization of ecological networks beyond shifts in aquatic metabolism.