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Grimm, Nancy B.; Petrone, Kevin C.

doi:10.1023/a:1005798410819

Cited by 114 publications

(25 citation statements)

References 51 publications

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“…We did not, however, measure N 2 fixation at night and consequently cannot rule out N 2 fixation by unicellular cyanobacteria, which are abundant in our study lakes (Budy et al 1995). The N 2 -fixation rates in our streams were low compared to those reported in desert streams (Grimm and Petrone 1997) or California coastal streams with large populations of Nostoc sp. (Horne and Carmiggelt 1975), but similar to those observed in two Antarctic streams (HowardWilliams et al 1989).…”

Section: Discussioncontrasting

confidence: 86%

“…First, N 2 -fixation contributions are dependent on the total surface area of the habitat studied, because as surface area increases the amount of N introduced via N 2 fixation increases. In contrast, hydrologic N fluxes are not spatially dependent (Cummins et al 1983, Grimm andPetrone 1997). The very large surface areas of the lakes certainly contributed to the more important role for N 2 fixation in lakes versus streams in our analysis: lakes are simply much larger areas where N 2 fixation can occur, while streams comprise a relatively small overall portion of our study watersheds.…”

Section: Discussionmentioning

confidence: 78%

“…In contrast, hydrologic N flux does not consider the fate of that N once it enters a stream reach, where it can pass through unaltered, be retained temporarily via cycling by the biota, be transformed and exported in a different N form, or be lost permanently via denitrification. A more useful comparison may be between N 2 fixation and the amount of N retained as periphyton biomass (e.g., Grimm and Petrone 1997) or uptake rates of inorganic N (Newbold 1992). By comparing N 2 -fixation rates and cell N content, Scott et al (2007) found that N 2 fixation contributed about 30% of the N content of metaphyton (floating algal and microbial mats) in a wetland.…”

Section: Discussionmentioning

confidence: 99%

“…For this purpose, we assumed that nighttime rates in our system were zero, which is supported by studies showing that N 2 -fixation rates decrease significantly (but do not always cease) in the dark when cyanobacteria are the primary N 2 fixers (Livingstone et al 1985;Grimm and Petrone 1997). We are likely underestimating the daily contribution of N 2 fixation by assuming that nighttime rates are zero and that light/dark N 2 -fixation ratios do not vary by cover type (Enrich-Prast and Esteves 1998), so our estimates should be considered conservative.…”

Section: N 2 Fixation and Hydrologic N Flux Calculationsmentioning

confidence: 96%

“…In streams, N 2 fixation has seldom been measured, despite the common presence of N 2 -fixing taxa in benthic stream communities (Marcarelli et al 2008). Estimates in a desert stream indicated that annual N 2 fixation was comparable to annual rates measured in eutrophic lakes and rice fields (Grimm and Petrone 1997), and natural and experimental N enrichments have demonstrated that increased inorganic N concentrations decrease cyanobacterial abundance and N 2 -fixation rates in N-limited streams (Henry and Fisher 2003;Marcarelli and Wurtsbaugh 2007). However, a comprehensive analysis of the importance of N 2 fixation to N-limited streams including seasonal trends and comparison to other N fluxes is lacking (but see Grimm and Petrone 1997).…”

Section: Introductionmentioning

confidence: 99%

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Nitrogen fixation varies spatially and seasonally in linked stream-lake ecosystems

Marcarelli

Wurtsbaugh

2009

Biogeochemistry

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We performed surveys of nitrogen (N 2 )-fixation in three oligotrophic lake-stream systems in the Sawtooth Mountains of central Idaho to address two questions: (1) Which habitat types within linked lake-stream systems (lake pelagic, lake benthic, and stream) exhibit the highest rates of N 2 fixation?, and (2) How does N 2 fixation compare to the hydrologic flux of nitrogen? A seasonal survey showed that N 2 fixation in a single lake and its outlet stream peaked in late summer, when hydrologic N fluxes were lowest. Benthic lake N 2 -fixation rates by epiphytes were highest at mid-lake depths, where their percent cover was highest, while rates by epipelon were greatest at shallow lake depths. Pelagic N 2 fixation was below detection. Stream N 2 -fixation rates were greatest on rock substrates and in the lake outlet stream. These patterns were supported by a baseflow survey (late July) in three lake-stream ecosystems which confirmed that N 2 -fixation rates peaked in the lake benthos at shallow depths and on rock substrates in outlet streams. Scaling N 2 -fixation rates to whole lake and stream areas revealed that N 2 fixation could exceed the nitrate, and sometimes the total dissolved nitrogen flux during baseflow in lakes and outlet streams. Despite low rates, total N 2 -fixation contributions (kg/day) from lakes were greater because they had far larger surface areas than the stream environments. Fixed nitrogen contributions from stream outlets were also relatively high because of high N 2 -fixation rates and despite low surface areas. This study suggests that N 2 fixation could be a seasonally important nitrogen source to nutrient deficient subalpine lake-stream ecosystems. In addition, the frequency and location of lakes could control N 2 -fixation contributions to watersheds by providing a large area for within-lake N 2 fixation, and creating conditions favorable for N 2 fixation in outlet streams.

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Section: Discussioncontrasting

confidence: 86%

Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: N 2 Fixation and Hydrologic N Flux Calculationsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Nitrogen fixation varies spatially and seasonally in linked stream-lake ecosystems

Marcarelli

Wurtsbaugh

2009

Biogeochemistry

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High frequency measurements of reach scale nitrogen uptake in a fourth order river with contrasting hydromorphology and variable water chemistry (Weiße Elster, Germany)

Kunz

Hensley

Brase

et al. 2017

Water Resources Research

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River networks exhibit a globally important capacity to retain and process nitrogen. However direct measurement of in‐stream removal in higher order streams and rivers has been extremely limited. The recent advent of automated sensors has allowed high frequency measurements, and the development of new passive methods of quantifying nitrogen uptake which are scalable across river size. Here we extend these methods to higher order streams with anthropogenically elevated nitrogen levels, substantial tributaries, complex input signals, and multiple N species. We use a combination of two station time‐series and longitudinal profiling of nitrate to assess differences in nitrogen processing dynamics in a natural versus a channelized impounded reach with WWTP effluent impacted water chemistry. Our results suggest that net mass removal rates of nitrate were markedly higher in the unmodified reach. Additionally, seasonal variations in temperature and insolation affected the relative contribution of assimilatory versus dissimilatory uptake processes, with the latter exhibiting a stronger positive dependence on temperature. From a methodological perspective, we demonstrate that a mass balance approach based on high frequency data can be useful in deriving quantitative uptake estimates, even under dynamic inputs and lateral tributary inflow. However, uncertainty in diffuse groundwater inputs and more importantly the effects of alternative nitrogen species, in this case ammonium, pose considerable challenges to this method.

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Microbial Ecology of Streams

Leff

2019

Encyclopedia of Water

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Streams present microorganisms with a unique set of physical and chemical conditions. The most apparent is the unidirectional flow of water. Streams also have strong interconnections to the surrounding landscape and are often exposed to extensive anthropogenic disturbance. This article is divided into three main sections: diversity and composition of microbial communities, biogeochemical functions, and anthropogenic impacts. In terms of diversity, high‐throughput sequencing has transformed microbial ecology; yet, streams and some taxa are relatively understudied. The dynamic nature of streams and large temporal and spatial differences also create challenges for development of generalities. The roles of microbes in organic matter processing and nutrient cycling in streams are clear, and the fate of nutrients has a large impact on downstream processes, such as eutrophication. Humans impact streams in a variety of ways that, in turn, alter the physiochemical conditions and microbial ecology. Often these impacts are combined, such as multiple pollutants in a channelized stream, making it difficult to discern the cause and effect. Overall, microbes are central to function of stream ecosystems biogeochemically. This coupled with the importance of streams to humanity makes the study of stream microbial ecology crucial. Molecular methods are at the heart of microbial ecology, and studies of streams also benefit from this approach.

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Untitled

Cited by 114 publications

References 51 publications

Nitrogen fixation varies spatially and seasonally in linked stream-lake ecosystems

Nitrogen fixation varies spatially and seasonally in linked stream-lake ecosystems

High frequency measurements of reach scale nitrogen uptake in a fourth order river with contrasting hydromorphology and variable water chemistry (Weiße Elster, Germany)

Microbial Ecology of Streams

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