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Hydrological pulse regulating the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes.

Vidal LO, Abril G, Artigas LF, Melo ML, Bernardes MC, Lobão LM, Reis MC, Moreira-Turcq P, Benedetti M, Tornisielo VL, Roland F - Front Microbiol (2015)

Bottom Line: Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration.In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW.Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Ciências Ambientais, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Rio de Janeiro, Brazil.

ABSTRACT
We evaluated in situ rates of bacterial carbon processing in Amazonian floodplain lakes and mainstems, during both high water (HW) and low water (LW) phases (p < 0.05). Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration. Bacterial carbon demand was mostly accounted by BR and presented the same pattern that BR in both water phases. Bacterial growth efficiency (BGE) showed a wide range (0.2-23%) and low mean value of 3 and 6%, (in HW and LW, respectively) suggesting that dissolved organic carbon was mostly allocated to catabolic metabolism. However, BGE was regulated by BP in LW phase. Consequently, changes in BGE showed the same pattern that BP. In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW. Multiple correlation analyses revealed that indexes of organic matter (OM) quality (chlorophyll-a, N stable isotopes and C/N ratios) were the strongest seasonal drivers of bacterial carbon metabolism. Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality.

No MeSH data available.


Bacterial carbon demand (BCD) across the Amazon River system in HW (left upper panel) and LW (right upper panel). CA, Cabaliana; JA, Janauacá; NR, Negro River; AR, Amazonas River; MR, Madeira River; MI, Miratuba; C, Curuai; TA, Tapajós River (upper panel). Average and standard deviation for the mainstems and floodplain lakes in HW (left bottom panel) and LW (right bottom panel).
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Figure 5: Bacterial carbon demand (BCD) across the Amazon River system in HW (left upper panel) and LW (right upper panel). CA, Cabaliana; JA, Janauacá; NR, Negro River; AR, Amazonas River; MR, Madeira River; MI, Miratuba; C, Curuai; TA, Tapajós River (upper panel). Average and standard deviation for the mainstems and floodplain lakes in HW (left bottom panel) and LW (right bottom panel).

Mentions: The BCD varied from 1.58 to 12.36 μg C L-1 h-1 (6.27 ± 4.82) in mainstems and from 5.94 to 17.84 μg C L-1 h-1 (8.88 ± 5.33) in floodplain lakes in HW (Figure 4). In LW, BCD varied from 9.6 to 14.76 μg C L-1 h-1 (12.18 ± 3.65) in mainstems and from 9.57 to 19.62 μg C L-1 h-1 (15.98 ± 4.57) in floodplain lakes. The BCD did not show any significant difference between mainstems and floodplain lakes in HW and LW (p > 0.05). The lack of correlation between the simultaneous measurements of BP and BR in both sampling conditions resulted in a wide range of calculated BGE. BGE varied from 0.01 to 0.18 (0.05 ± 0.06) on mainstems and from 0.002 to 0.07 (0.05 ± 0.03) on floodplain lakes in HW, and from 0.02 to 0.03 (0.02 ± 0.007) in mainstems and from 0.03 to 0.23 (0.12 ± 0.08) in floodplain lakes in LW (Figure 5). The BGE in floodplain lakes were significantly higher (p < 0.05) than in mainstem in LW (Figure 4) and mainly driven by BP (Tables 2 and 3). During HWs, no significant difference was observed between the mainstem and the floodplain lakes (p > 0.05). No correlation was found between BP and BR in either sampling periods.


Hydrological pulse regulating the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes.

Vidal LO, Abril G, Artigas LF, Melo ML, Bernardes MC, Lobão LM, Reis MC, Moreira-Turcq P, Benedetti M, Tornisielo VL, Roland F - Front Microbiol (2015)

Bacterial carbon demand (BCD) across the Amazon River system in HW (left upper panel) and LW (right upper panel). CA, Cabaliana; JA, Janauacá; NR, Negro River; AR, Amazonas River; MR, Madeira River; MI, Miratuba; C, Curuai; TA, Tapajós River (upper panel). Average and standard deviation for the mainstems and floodplain lakes in HW (left bottom panel) and LW (right bottom panel).
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Figure 5: Bacterial carbon demand (BCD) across the Amazon River system in HW (left upper panel) and LW (right upper panel). CA, Cabaliana; JA, Janauacá; NR, Negro River; AR, Amazonas River; MR, Madeira River; MI, Miratuba; C, Curuai; TA, Tapajós River (upper panel). Average and standard deviation for the mainstems and floodplain lakes in HW (left bottom panel) and LW (right bottom panel).
Mentions: The BCD varied from 1.58 to 12.36 μg C L-1 h-1 (6.27 ± 4.82) in mainstems and from 5.94 to 17.84 μg C L-1 h-1 (8.88 ± 5.33) in floodplain lakes in HW (Figure 4). In LW, BCD varied from 9.6 to 14.76 μg C L-1 h-1 (12.18 ± 3.65) in mainstems and from 9.57 to 19.62 μg C L-1 h-1 (15.98 ± 4.57) in floodplain lakes. The BCD did not show any significant difference between mainstems and floodplain lakes in HW and LW (p > 0.05). The lack of correlation between the simultaneous measurements of BP and BR in both sampling conditions resulted in a wide range of calculated BGE. BGE varied from 0.01 to 0.18 (0.05 ± 0.06) on mainstems and from 0.002 to 0.07 (0.05 ± 0.03) on floodplain lakes in HW, and from 0.02 to 0.03 (0.02 ± 0.007) in mainstems and from 0.03 to 0.23 (0.12 ± 0.08) in floodplain lakes in LW (Figure 5). The BGE in floodplain lakes were significantly higher (p < 0.05) than in mainstem in LW (Figure 4) and mainly driven by BP (Tables 2 and 3). During HWs, no significant difference was observed between the mainstem and the floodplain lakes (p > 0.05). No correlation was found between BP and BR in either sampling periods.

Bottom Line: Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration.In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW.Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality.

View Article: PubMed Central - PubMed

Affiliation: Laboratório de Ciências Ambientais, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Rio de Janeiro, Brazil.

ABSTRACT
We evaluated in situ rates of bacterial carbon processing in Amazonian floodplain lakes and mainstems, during both high water (HW) and low water (LW) phases (p < 0.05). Our results showed that bacterial production (BP) was lower and more variable than bacterial respiration, determined as total respiration. Bacterial carbon demand was mostly accounted by BR and presented the same pattern that BR in both water phases. Bacterial growth efficiency (BGE) showed a wide range (0.2-23%) and low mean value of 3 and 6%, (in HW and LW, respectively) suggesting that dissolved organic carbon was mostly allocated to catabolic metabolism. However, BGE was regulated by BP in LW phase. Consequently, changes in BGE showed the same pattern that BP. In addition, the hydrological pulse effects on mainstems and floodplains lakes connectivity were found for BP and BGE in LW. Multiple correlation analyses revealed that indexes of organic matter (OM) quality (chlorophyll-a, N stable isotopes and C/N ratios) were the strongest seasonal drivers of bacterial carbon metabolism. Our work indicated that: (i) the bacterial metabolism was mostly driven by respiration in Amazonian aquatic ecosystems resulting in low BGE in either high or LW phase; (ii) the hydrological pulse regulated the bacterial heterotrophic metabolism between Amazonian mainstems and floodplain lakes mostly driven by OM quality.

No MeSH data available.