High Primary Production Contrasts with Intense Carbon Emission in a Eutrophic Tropical Reservoir

Autor(es):Mostrar menos -

Almeida, Rafael M. ^[1] ; Nobrega, Gabriel N. ^[2] ; Junger, Pedro C. ^[3] ; Figueiredo, Aline V. ^[4] ; Andrade, Anizio S. ^[5] ; de Moura, Caroline G. B. ^[5] ; Tonetta, Denise ^[6] ; Oliveira, Jr., Ernandes S. ^[7] ; Araujo, Fabiana ^[4] ; Rust, Felipe ^[1] ; Pineiro-Guerra, Juan M. ^{[8, 9]} ; Mendonca, Jr., Jurandir R. ^[4] ; Medeiros, Leonardo R. ^[5] ; Pinheiro, Lorena ^[10] ; Miranda, Marcela ^[1] ; Costa, Mariana R. A. ^[4] ; Melo, Michaela L. ^[11] ; Nobre, Regina L. G. ^[5] ; Benevides, Thiago ^[3] ; Roland, Fabio ^[1] ; de Klein, Jeroen ^[12] ; Barros, Nathan O. ^[1] ; Mendonca, Raquel ^{[1, 13]} ; Becker, Vanessa ^[4] ; Huszar, Veral. M. ^[14] ; Kosten, Sarian ^[7]

Afiliação do(s) autor(es):Mostrar menos -

^[1] Univ Fed Juiz de Fora, Inst Ciencias Biol, Dept Biol, Aquat Ecol Lab, Juiz De Fora - Brazil

^[2] Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, Dept Ciencia Solo, Piracicaba - Brazil

^[3] Univ Fed Rio de Janeiro, Lab Limnol, Rio De Janeiro - Brazil

^[4] Univ Fed Rio Grande do Norte, Lab Water Resources & Environm Sanitat, BR-59072970 Natal, RN - Brazil

^[5] Univ Fed Rio Grande do Norte, Lab Limnol, BR-59072970 Natal, RN - Brazil

^[6] Univ Fed Santa Catarina, Lab Freshwater Ecol, Florianopolis, SC - Brazil

^[7] Radboud Univ Nijmegen, Dept Aquat Ecol & Environm Biol, Inst Water & Wetland Res, NL-6525 ED Nijmegen - Netherlands

^[8] Univ Republica, Fac Ciencias, Montevideo - Uruguay

^[9] Univ Republica, Dept Ecol Teor & Aplicada, Ctr Univ Reg Este, Montevideo - Uruguay

^[10] Univ Fed Estado Rio de Janeiro, Dept Ciencias Nat, Rio De Janeiro - Brazil

^[11] Univ Fed Sao Carlos, Lab Microbial Proc & Biodivers, BR-13560 Sao Carlos, SP - Brazil

^[12] Wageningen Univ, Aquat Ecol & Environm Sci, NL-6700 AP Wageningen - Netherlands

^[13] Uppsala Univ, Dept Ecol & Genet, Uppsala - Sweden

^[14] Univ Fed Rio de Janeiro, Museu Nacl, Lab Ficol, Rio De Janeiro - Brazil

• Tipo de documento: Artigo Científico
• Fonte: FRONTIERS IN MICROBIOLOGY; v. 7, MAY 18 2016.
• Citações Web of Science: 22

Resumo

Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (Co-2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic carbon (C) fluxes in warm waters. We test the hypothesis that a warm eutrophic system is a source of both CO2 and CH4 to the atmosphere, and that atmospheric emissions are larger than the burial of OC in sediments. This hypothesis was based on the following assumptions: (i) OC mineralization rates are high in warm water systems, so that water column CO2 production overrides the high C uptake by primary producers, and (ii) increasing trophic status creates favorable conditions for CH4 production. We measured water-air and sediment-water CO2 fluxes, CH4 diffusion, ebullition and oxidation, net ecosystem production (NEP) and sediment OC burial during the dry season in a eutrophic reservoir in the semiarid northeastern Brazil. The reservoir was stratified during daytime and mixed during nighttime. In spite of the high rates of primary production (4858 +/- 934 mg C m(-2) d(-1)), net heterotrophy was prevalent due to high ecosystem respiration (5209 +/- 992 mg C m(-2) d(-1)). Consequently, the reservoir was a source of atmospheric CO2 (518 +/- 182 mg C m(-2) d(-1)). In addition, the reservoir was a source of ebullitive (17 +/- 10 mg C m(-2) d(-1)) and diffusive CH4 (11 +/- 6 mg C m(-2) d(-1)). OC sedimentation was high (1162 mg C m(-2) d(-1)), but our results suggest that the majority of it is mineralized to CO2 (722 +/- 182 mg C m(-2) d(-1)) rather than buried as OC (440 mg C m(-2) d(-1)). Although temporally resolved data would render our findings more conclusive, our results suggest that despite being a primary production and OC burial hotspot, the tropical eutrophic system studied here was a stronger CO2 and CH4 source than a C sink, mainly because of high rates of OC mineralization in the water column and sediments. (AU)

• Processo FAPESP: 14/11778-5 - Solos subaquáticos de pradarias marinhas (seagrass bed) do Brasil: biogeoquímica, gênese e classificação
• Beneficiário: Gabriel Nuto Nóbrega
• Modalidade de apoio: Bolsas no Brasil - Doutorado