Demographic and mutualistic responses of stream nitrogen fixers to nutrients

Kunza, Lisa A.; Hall, Robert O.

doi:10.1899/12-102.1

Cited by 16 publications

(21 citation statements)

References 59 publications

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“…Model estimates of N 2 consumption are higher than reported rates of N 2 fixation which range from 0 to 0.2 g N 2 –N m −2 d −1 (Marcarelli et al ). It may be unlikely that the magnitude of N 2 consumption observed in these systems is solely attributable to N 2 fixation as N 2 fixation rates are predicted to be negligible above 20 μ g DIN L −1 (Kunza and Hall , ). Yet, it is possible that other factors such as light, temperature, and element availability may be important controls on N 2 fixation rates (Marcarelli and Wurtsbaugh ; Finlay et al ; Kunza and Hall ; Welter et al ).…”

Section: Discussionmentioning

confidence: 99%

“…It may be unlikely that the magnitude of N 2 consumption observed in these systems is solely attributable to N 2 fixation as N 2 fixation rates are predicted to be negligible above 20 μ g DIN L −1 (Kunza and Hall , ). Yet, it is possible that other factors such as light, temperature, and element availability may be important controls on N 2 fixation rates (Marcarelli and Wurtsbaugh ; Finlay et al ; Kunza and Hall ; Welter et al ). In contrast, Christensen et al () observed as high as an 85% reduction in denitrification when comparing rates between light and dark treatments which could contribute to decreased N 2 concentrations during the day, but not necessarily below saturation values.…”

Section: Discussionmentioning

confidence: 99%

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Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models

Nifong

Taylor

Adams

et al. 2020

Limnology & Ocean Methods

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There is keen interest to enhance denitrification within intervening aquatic habitats between agricultural areas and downstream aquatic ecosystems to reduce nitrogen (N) loading impacts to receiving ecosystems. We conducted a series of measurements to examine whole system in situ diel denitrification estimates in experimental ditch and stream environments using a Bayesian one-station diel N 2 flux model. Model estimates revealed complex patterns that indicate fluxes may be controlled by the balance of both N 2 production via denitrification and consumption driven by physical or biological processes associated with strong diel patterns in environmental conditions. We investigated potential improvements in model fits to observed data associated with the addition of a N 2 consumption term to represent biological (N 2 fixation) or physical (bubble formation and N 2 scavenging) mechanisms associated with daytime photosynthesis. We also expanded the current one-station diel flux model to a two-station model to estimate denitrification in discrete reaches. Our modified diel N 2 flux models improved model fit significantly across three metrics (Nash-Sutcliffe efficiency, root mean square ratio, and percent bias) increasing their utility in shallow, open canopy, lotic systems. While more studies are needed to understand specific mechanisms associated with N 2 consumption processes in small agricultural drainages as well as environmental conditions affecting their relative importance, these results improve estimates of N 2 flux where dynamic conditions and heterogeneity of habitats create severe diel patterns in factors controlling dissolved gas concentrations and prohibit accurate estimates of N 2 flux using existing models.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models

Nifong

Taylor

Adams

et al. 2020

Limnology & Ocean Methods

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“…We measured N 2 fixation rates across a DIN gradient associated with % alder cover, so we did not choose sites that had universally low DIN and an associated expectation of high N 2 fixation rates, as has been suggested for a bias in N 2 fixation rates in the literature (Marcarelli et al 2008). Temperatures in south-central Alaska headwater streams rarely are >107C, which is colder than streams used in most N 2fixation studies (e.g., Scott et al 2009, Lang et al 2012, Kunza and Hall 2013, reviewed by Marcarelli et al 2008. This low temperature could lead to low biomass accumulation, favor non-N 2 -fixing communities, and physiologically limit N 2 fixation rates (Marcarelli and Wurtsbaugh 2006).…”

Section: Discussionmentioning

confidence: 99%

“…In addition to being ubiquitous in alder, N 2 fixation can be accomplished in streams by cyanobacteria or diatoms with cyanobacterial endosymbionts Wurtsbaugh 2006, Kunza andHall 2013). Acquiring N via N 2 fixation is energetically costly compared to inorganic N uptake (Howarth et al 1988, Vitousek et al 2002, so low DIN (NO 3 -N 1 NO 2 -N 1 NH 4 -N) concentrations strongly favor microbial N 2 fixers and increase aquatic N 2 fixation rates (Howarth et al 1988, Marcarelli and Wurtsbaugh 2006, Scott et al 2009, Lang et al 2012, Kunza and Hall 2013. DIN is recognized as a critical control on in-stream N 2 fixation rates (Howarth et al 1988).…”

mentioning

confidence: 99%

Catchment-scale alder cover controls nitrogen fixation in boreal headwater streams

Hiatt¹,

Robbins²,

Back³

et al. 2017

Freshwater Science

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Alder (Alnus spp.) is a woody plant with bacterial symbionts that fix atmospheric N 2 into bioavailable N. We studied 12 North American boreal headwater streams spanning a steep gradient of catchment alder cover (0-27%) to test the hypothesis that increasing inputs of inorganic N associated with increasing alder cover would reduce or eliminate in-stream benthic N 2 fixation. We measured N 2 fixation rates, chlorophyll a, and ash-free dry mass (AFDM) of periphyton in early (May) and late (August) summer 2011. Dissolved inorganic N (DIN) concentrations, composed almost entirely of NO 3 /NO 2-N, ranged from below detection limits to nearly 2 mg/L and were strongly predicted by catchment alder cover in both months. Higher N 2 fixation rates were observed in August than in May. N 2 fixation rates declined sharply when alder cover exceeded~2% of catchment cover, corresponding to 20 to 40 lg/L DIN. This pattern also was evident among 3 streams with contrasting catchment alder cover sampled approximately every 2 wk during the study. The stream with no catchment alder cover exhibited a steady increase in N 2 fixation rates over the summer, whereas the streams with low and high alder in their catchments had very low N 2 fixation rates that did not vary over time. The influence of alder cover on periphyton biomass was not clear. The strong regulation of alder cover on in-stream N availability leads us to suggest that alder presence may be an important terrestrial regulator of stream N cycling.

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“…A review of the gene expression that takes place during heterocyte formation in cyanobacteria contributed to our understanding of the molecular mechanisms involved in this process, especially with respect to the promoters of these genes (Herrero et al, 2013). Using short-term nutrient additions, Kunza and Hall (2013) assessed the effects of macronutrients (nitrogen, phosphorus) and micronutrients (iron and molybdenum; cofactors of nitrogenase) on N 2 -fixation rates and the biomass and species composition of epilithic biofilms.…”

Section: Nitrogen-fixation Several New Advances Werementioning

confidence: 99%

Substratum‐Associated Microbiota

Furey

Liess

2014

Water Environment Research

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A review of literature on substratrumassociated microbiotia from 2013 covers topics on benthic algae, bacteria and viruses from a range of aquatic environments, but focuses on freshwater ecosystems. Advances in laboratory, field, and assessment methods are highlighted as are updates in taxonomy and systematics. Aspects of water quality, waste‐water treatment, biofuels, nutrient cycling, food‐web interactions, land use changes, and environmental challenges such as climate change, pollutants, and impacts of medical substances are presented. our understanding of the ecology, taxonomy and assessment of substratum‐associated microbiota. In response to increased pressures from anthropogenic stressors and climate change on aquatic environments, researchers are re‐evaluating current knowledge and approaches to research, biomonitoring and assessment. In this review of the 2013 literature, advances in laboratory, field, and assessment methods are highlighted as are updates in taxonomy and systematics. A literature review of similar topics was completed in 2013 (Furey and Liess, 2013).

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Demographic and mutualistic responses of stream nitrogen fixers to nutrients

Cited by 16 publications

References 59 publications

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models

Catchment-scale alder cover controls nitrogen fixation in boreal headwater streams

Substratum‐Associated Microbiota

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Demographic and mutualistic responses of stream nitrogen fixers to nutrients

Cited by 16 publications

References 59 publications

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N2 flux models

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N2 flux models

Catchment-scale alder cover controls nitrogen fixation in boreal headwater streams

Substratum‐Associated Microbiota

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Product

Resources

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Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models

Recognizing both denitrification and nitrogen consumption improves performance of stream diel N₂ flux models