A mechanistic-based framework to understand how dissolved organic carbon is processed in a large fluvial lake
2013
Massicotte, Philippe | Frenette, Jean-Jacques
Lay AbstractDissolved organic carbon (DOC) is a fundamental component of the biogeochemical cycling of nutrients in aquatic ecosystems and is the main carbon source supporting bacterial production. The efficiency at which heterotrophic (nonphotosynthetic) bacteria convert this substrate into biomass depends mainly on the quality of DOC in the water column. DOC is constantly processed through various physical, chemical, and biological mechanisms that operate simultaneously and alter its quality. It is paramount to understand how these different processes interact to drive the fate of DOC in aquatic ecosystems. Based on field data collected in a large fluvial lake, we developed and validated a mechanistic model that provides a framework to understand the relative contribution of the main processes involved in both labile (DOCL) and semilabile (DOCSL) DOC pool kinetics. The model revealed that during the downstream flow, each category of DOC pool was processed differently by bacteria: DOCL was preferentially used for biomass production, whereas DOCSL completed bacterial carbon demand. Our results also suggest that a decrease in DOCL abundance will further determine the intake of DOCSL.
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