Carbon and phosphorus regulating bacterial metabolism in oligotrophic boreal lakes

Vidal, Luciana O.; Granéli, Wilhelm; Daniel, Cesar Bolivar; Heiberg, Lisa; Roland, Fábio

doi:10.1093/plankt/fbr059

Cited by 29 publications

(26 citation statements)

References 41 publications

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“…In lakes, BGE range has generally varied between ca. 10 and 40 % (del Giorgio and Cole 1998;Vidal et al 2011). In boreal rivers and brooks, Berggren et al (2007) observed increased BGE in bacteria (from ca.…”

Section: Discussionmentioning

confidence: 97%

Short-term effects of phosphorus addition and pH rise on bacterial utilization and biodegradation of dissolved organic carbon (DOC) from boreal mires

et al. 2014

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Natural mires and forested peatlands are known to be very significant sources of dissolved organic carbon (DOC) to aquatic ecosystems. Peatland management operations (e.g., forestry operations, restoration of drained mires and peat mining) and extreme hydrological events may increase the DOC runoff. We hypothesized that an increase in phosphorus (P) leaching, together with near-neutral conditions in recipient lakes will accelerate decomposition of DOC that originates from acidic, nutrient-poor mire waters. The efficiency of DOC utilization was evaluated by measuring microbial respiration and bacterial production (BP) in short-term laboratory experiments with runoff waters from six boreal mire sites. Mere inorganic phosphorus (PO 4 -P) addition did not affect the rate of respiration or the proportion of decayed DOC. However, in the nutrient-poor bog waters, P addition slightly promoted BP and bacterial growth efficiency (BGE). In contrast, the elevation of pH alone, and the elevation of pH and PO 4 -P level together, caused a significant increase in respiration and in the proportion of decayed DOC, but did not affect net BP. Elevated pH alone, however, depressed BGE when compared to that under the combined elevation of pH and PO 4 -P. These results suggest that the increased P availability, e.g., after mire restoration, would slightly benefit bacterial net growth in P-limited waters. However, in near-neutral recipient lakes, the increased microbial decomposition of mire-originated DOC contributes more to carbon dioxide (CO 2 ) supersaturation than potentially supporting detritusbased food chains.

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Section: Discussionmentioning

confidence: 97%

Short-term effects of phosphorus addition and pH rise on bacterial utilization and biodegradation of dissolved organic carbon (DOC) from boreal mires

et al. 2014

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“…As noted by Vidal et al (2011), not only carbon, but the carbon: phosphorus ratio controls bacterial production and respiration in lakes, and even a situation of labile DOC accumulation can occur under phosphorus limitation (Vadstein et al, 2003). In fact, increased bacterial density in the presence of macrophytes after phosphorus amendment has been described (Huss and Wehr, 2004; Joniak et al, 2007; Morozova et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

2013

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Macrophytes are important sources of dissolved organic carbon (DOC) to littoral zones of lakes, but this DOC is believed to be mostly refractory to bacteria, leading to the hypothesis that bacterial metabolism is different in littoral and pelagic zones of a large subtropical shallow lake. We tested this hypothesis by three approaches: (I) dissolved inorganic carbon (DIC) accumulation in littoral and pelagic water; (II) O2 consumption estimate for a cloud of points (n = 47) covering the entire lake; (III) measurement of O2 consumption and CO2 accumulation in dark bottles, pCO2 in the water, lake-atmosphere fluxes of CO2 (fCO2) and a large set of limnological variables at 19 sampling points (littoral and pelagic zones) during seven extensive campaigns. For the first two approaches, DIC and O2 consumption were consistently lower in the littoral zone, and O2 consumption increased marginally with the distance to the nearest shore. For the third approach, we found in the littoral zone consistently lower DOC, total phosphorus (TP), and chlorophyll a, and a higher proportion of low-molecular-weight substances. Regression trees confirmed that high respiration (O2 consumption and CO2 production) was associated to lower concentration of low-molecular-weight substances, while pCO2 was associated to DOC and TP, confirming that CO2 supersaturation occurs in an attempt to balance phosphorus deficiency of macrophyte substrates. Littoral zone fCO2 showed a tendency to be a CO2 sink, whereas the pelagic zone showed a tendency to act as CO2 source to the atmosphere. The high proportion of low-molecular-weight, unreactive substances, together with lower DOC and TP may impose lower rates of respiration in littoral zones. This effect of perennial stands of macrophytes may therefore have important, but not yet quantified implications for the global carbon metabolism of these lakes, but other issues still need to be carefully addressed before rejecting the general belief that macrophytes are always beneficial to bacteria.

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“…Thus, studies performed in freshwater ecosystems involve arctic and alpine lakes [20], [29], tropical regions [26], [30], [31] or humic lakes [13], whereas inland waters of Mediterranean region have received less attention. Noticeably, the Mediterranean ecoregion shows a broad intersystem trophic gradient for inland waters, not only throughout the entire ecoregion, but also locally [32].…”

Section: Introductionmentioning

confidence: 99%

Quantification of Carbon and Phosphorus Co-Limitation in Bacterioplankton: New Insights on an Old Topic

et al. 2014

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Because the nature of the main resource that limits bacterioplankton (e.g. organic carbon [C] or phosphorus [P]) has biogeochemical implications concerning organic C accumulation in freshwater ecosystems, empirical knowledge is needed concerning how bacteria respond to these two resources, available alone or together. We performed field experiments of resource manipulation (2×2 factorial design, with the addition of C, P, or both combined) in two Mediterranean freshwater ecosystems with contrasting trophic states (oligotrophy vs. eutrophy) and trophic natures (autotrophy vs. heterotrophy, measured as gross primary production:respiration ratio). Overall, the two resources synergistically co-limited bacterioplankton, i.e. the magnitude of the response of bacterial production and abundance to the two resources combined was higher than the additive response in both ecosystems. However, bacteria also responded positively to single P and C additions in the eutrophic ecosystem, but not to single C in the oligotrophic one, consistent with the value of the ratio between bacterial C demand and algal C supply. Accordingly, the trophic nature rather than the trophic state of the ecosystems proves to be a key feature determining the expected types of resource co-limitation of bacteria, as summarized in a proposed theoretical framework. The actual types of co-limitation shifted over time and partially deviated (a lesser degree of synergism) from the theoretical expectations, particularly in the eutrophic ecosystem. These deviations may be explained by extrinsic ecological forces to physiological limitations of bacteria, such as predation, whose role in our experiments is supported by the relationship between the dynamics of bacteria and bacterivores tested by SEMs (structural equation models). Our study, in line with the increasingly recognized role of freshwater ecosystems in the global C cycle, suggests that further attention should be focussed on the biotic interactions that modulate resource co-limitation of bacteria.

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Carbon and phosphorus regulating bacterial metabolism in oligotrophic boreal lakes

Cited by 29 publications

References 41 publications

Short-term effects of phosphorus addition and pH rise on bacterial utilization and biodegradation of dissolved organic carbon (DOC) from boreal mires

Short-term effects of phosphorus addition and pH rise on bacterial utilization and biodegradation of dissolved organic carbon (DOC) from boreal mires

Lower Respiration in the Littoral Zone of a Subtropical Shallow Lake

Quantification of Carbon and Phosphorus Co-Limitation in Bacterioplankton: New Insights on an Old Topic

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