Productivity and rainfall drive bacterial metabolism in tropical cascading reservoirs

Author(s)

Freitas, Roberta ^[1] ; Vieira, Helena Henriques ^[2] ; de Moraes, Guilherme Pavan ^[2] ; de Melo, Michaela Ladeira ^[1] ; Henriques Vieira, Armando Augusto ^[2] ; Sarmento, Hugo ^[1]

Affiliation

^[1] Univ Fed Sao Carlos UFSCar, Lab Microbial Proc & Biodivers, Dept Hydrobiol DHb, Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos UFSCar, Lab Phycol, DB, Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Hydrobiologia; v. 809, n. 1, p. 233-246, MAR 2018.
• Web of Science Citations: 2

Abstract

Tropical reservoirs are main carbon sources to the atmosphere, and bacterial metabolism is a key process in these emissions. Here, we explored the drivers of bacterial metabolism in four tropical cascading reservoirs forming a trophic state gradient, and compared them with those found in the literature (mainly from temperate regions). Bacterial production (BP) and growth efficiency (BGE) responded to trophic state-related variables, while bacterial respiration (BR) was weakly and negatively correlated to dissolved organic carbon (DOC). BP and BGE were higher in reservoirs with higher primary production, while BR (high throughout the whole study period) was greater in less productive reservoirs, where planktonic communities were often limited by phosphorus. The high BR and low BGE observed in less productive downstream reservoirs (i.e., less nutrients and organic matter availability) may be explained by increasing nutrient limitation and proportion of recalcitrant DOC along the cascade. Despite the lower productivity, oligotrophic reservoirs may be more important in terms of carbon biogeochemistry, considering that microbes in those systems mineralize more carbon than upstream productive reservoirs. Moreover, the drivers of bacterial metabolism may act differently according to latitude, as seasonality in the tropics is determined mainly by rainfall rather than temperature. (AU)

• FAPESP's process: 11/50054-4 - Biodiversity of freshwater microalgae: germplasm bank and obtaining of molecular markers of cryopreserved species
• Grantee: Armando Augusto Henriques Vieira
• Support type: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 14/14139-3 - Microbial processes and biodiversity in aquatic ecosystems
• Grantee: Hugo Miguel Preto de Morais Sarmento
• Support type: Research Grants - Young Investigators Grants