Portal de Periódicos da CAPES

Artigo Acesso aberto Produção Nacional Revisado por pares

BIBTEX RIS

High bacterial carbon demand and low growth efficiency at a tropical hypereutrophic estuary: importance of dissolved organic matter remineralization

2017; UNIVERSIDADE DE SÃO PAULO; Volume: 65; Issue: 3 Linguagem: Inglês

10.1590/s1679-87592017137406503

1982-436X

M. Guenther, Eliane Gonzalez‐Rodriguez, Manuel Flores‐Montes, Moacyr Araújo, Sigrid Neumann‐Leitão,

Microbial Community Ecology and Physiology

Abstract Simultaneous measurements of bacterioplankton production (BP) and respiration (BR) are imperative to understand the magnitude of carbon cycle in the lower trophic levels of the aquatic systems, but are still scarce in the tropics. The present study was performed in a highly productive estuary (Recife harbor, 08°03'S; 34°52'W, NE Brazil) where bacterial carbon demand (BCD=BP+BR) and growth efficiency (BGE=BP/BCD) were evaluated in order to estimate the major role of bacterioplankton: source or sink of organic carbon. In spite of the high BP rates (0.03-0.4 µMC h-1), the extremely high BR rates (0.5-4.1 µMC h-1) led to low BGE (0.02-0.29), possibly due to the high temperatures (>25ºC) and strong inorganic nitrogen limitation (N:P ratios) The high BCD and low BGE indicate the major role of bacterioplankton as dissolved organic matter remineralizers, fueling the primary productivity of the system. These findings contradict what could be expected from studies in highly productive temperate estuaries (where BGE is usually > 0.30) and highlight the importance of increasing in situ BP and BR estimates in tropical estuarine systems in order to better understand the role of these systems in global carbon cycling.