In situ rapid measures of total respiration rate capture the super labile DOC bacterial substrates of freshwater

Pollard, Peter

doi:10.4319/lom.2013.11.584

Cited by 22 publications

(14 citation statements)

References 31 publications

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“…decreases primary production, pH, and dissolved oxygen (Stoler and Relyea 2016). Simultaneously, increased soluble carbon is associated with higher levels of microbial aerobic respiration, which can further decrease levels of dissolved oxygen (Pollard 2013). These patterns coincide with our observations of a negative relationship between structural trait means, chl a, and dissolved oxygen, and a positive relationship between structural trait means and light attenuation, pH, and periphyton biomass.…”

Section: Effects Of Diversity On Microbes Producers and Consumerssupporting

confidence: 89%

“…In contrast, the negative effect of soluble carbon on consumers is likely indirect: elevated levels of soluble carbon increases light attenuation, and Fig. Simultaneously, increased soluble carbon is associated with higher levels of microbial aerobic respiration, which can further decrease levels of dissolved oxygen (Pollard 2013). Nonmetric multidimensional scaling plots for bacteria and fungi community composition.…”

Section: Effects Of Diversity On Microbes Producers and Consumersmentioning

confidence: 99%

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Litter chemistry and chemical diversity drive ecosystem processes in forest ponds

Stoler

Burke²,

Relyea

2016

Ecology

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Research suggests that a positive relationship exists between diversity and ecological function, yet the multi-trophic effects of biodiversity remain poorly understood. The resource complementarity hypothesis suggests that increasing the trait diversity of resources provides a more complete diet for consumers, elevating consumer feeding rates. Whereas previous tests of this mechanism have measured trait diversity as the variation of single traits or the richness of functional groups, we employed a multivariate trait index to manipulate the chemical diversity of temperate tree litter species in outdoor pond mesocosms. We inoculated outdoor mesocosms with diverse and multi-trophic communities of microbial and macro-consumer species that rely on leaf litter for energy and nutrients. Litter was provided at three levels of chemical trait diversity, a constant level of species richness, and an equal representation of all litter species. Over three months, we measured more than 65 responses, and assessed the effects of litter chemical diversity and chemical trait means (i.e., community-weighted means). We found that litter chemical diversity positively correlated with decomposition rate of leaf litter, but had no effect on biomass or density of producers and consumers. However, the pond communities often responded to chemical trait means, particularly those related to nutrients, structure, and defense. Our results suggest that resource complementarity does have some effect on the release of energy and nutrients from decomposing substrates in forest ponds, but does not have multi-trophic effects. Our results further suggest that loss of tree biodiversity could affect forest ecosystem functionality, and particularly the processes occurring in and around ponds and wetlands.

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Section: Effects Of Diversity On Microbes Producers and Consumerssupporting

confidence: 89%

Section: Effects Of Diversity On Microbes Producers and Consumersmentioning

confidence: 99%

Litter chemistry and chemical diversity drive ecosystem processes in forest ponds

Stoler

Burke²,

Relyea

2016

Ecology

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“…Our initial apparent k values were considerably higher than those found in other lake studies using 20°C dark incubations (Koehler et al ; Mostovaya et al ). A possible reason for this difference is that the previous studies measured DOC concentrations with low temporal resolution (several days per measurement) while we used a high temporal resolution optical sensor approach, allowing us to detect some of the most labile DOC fractions used in the very beginning of the decay (Guillemette and del Giorgio ; Pollard ). After a few days of incubation, our k values had decreased to a range that represent the reactivity of a wide range of typical DOC molecules found in lakes (Mostovaya et al ), which together with low RMSE gives credibility to the modeled DOC decay.…”

Section: Discussionmentioning

confidence: 99%

Systematic microbial production of optically active dissolved organic matter in subarctic lake water

Berggren

Gudasz

Guillemette

et al. 2019

Limnology & Oceanography

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The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.

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“…In studies comparing biological availability of background DOC with macrophyte and algal leachates as well as terrestrial DOC extracts, bacterial production was higher in incubations with autochthonous and fresh (i.e., recently leached) terrestrial DOC than with bulk DOC [ Farjalla et al ., , ]. Measurements of bioassay DOC decay likely underestimate ecosystem‐level DOC turnover because bioassay incubations were limited to measuring the decay of DOC left over in river water after the rapid consumption of highly bioavailable DOC [ Pollard , ].…”

Section: Discussionmentioning

confidence: 99%

Modeling priming effects on microbial consumption of dissolved organic carbon in rivers

et al. 2014

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Rivers receive and process large quantities of terrestrial dissolved organic carbon (DOC).Biologically available (unstable) DOC leached from primary producers may stimulate (i.e., prime) the consumption of more stable terrestrially derived DOC by heterotrophic microbes. We measured microbial DOC consumption (i.e., decay rates) from contrasting C sources in 10 rivers in the western and Midwestern United States using short-term bioassays of river water, soil and algal leachates, glucose, and commercial humate. We added inorganic nutrients (ammonium and phosphorus) to a subset of bioassays. We also amended a subset of river, soil, and commercial humate bioassays with glucose or algal leachates to test the hypothesis that unstable DOC primes consumption of more stable DOC. We used prior measurements of source-specific DOC bioavailability, linked with a Bayesian process model, to estimate means and posterior probability distributions for source-specific DOC decay rates in multisource bioassays. Modeled priming effects ranged from a À130 to +370% change in more stable DOC decay when incubated with unstable DOC. Glucose increased modeled river DOC decay by an average of 87% among all rivers. Glucose and algal leachates increased soil leachate and commercial humate decay by an average of 25% above background rates. Inorganic nutrient additions did not have consistent effects on DOC decay, likely because most of the study rivers had high ambient background nutrients. Our results demonstrate that the priming effect can augment DOC decay in rivers. In addition, Bayesian models can be used to estimate mechanisms driving aquatic ecosystem processes that are difficult to measure directly.

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In situ rapid measures of total respiration rate capture the super labile DOC bacterial substrates of freshwater

Cited by 22 publications

References 31 publications

Litter chemistry and chemical diversity drive ecosystem processes in forest ponds

Litter chemistry and chemical diversity drive ecosystem processes in forest ponds

Systematic microbial production of optically active dissolved organic matter in subarctic lake water

Modeling priming effects on microbial consumption of dissolved organic carbon in rivers

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