Rates, Importance, and Controls of Nitrogen Fixation in Oligotrophic Arctic Lakes, Toolik, Alaska PDF Download
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Author: Gretchen Maria Gettel
Publisher:
ISBN:
Category :
Languages : en
Pages : 338
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Book Description
Biological nitrogen (N) fixation of atmospheric N2 by free-living cyanobacteria in aquatic environments is common, and in many ecosystems, it can account for a significant portion of the biologically available N inputs. Although N fixation can compensate for N limitation, N limitation is maintained over relatively long time scales in many oligotrophic lake ecosystems. This dissertation examines the importance of benthic and pelagic N fixation in the N economies of oligotrophic lakes in arctic Alaska (Chapter 1) and examines nutrient, light, and grazer controls on benthic N fixation (Chapters 2 and 3). Both benthic and pelagic N fixation are prevalent in many lakes across the Alaskan arctic landscape, ranging from 0.12 - 1.5 mg N m-2 day-1 and 0 - 2.56 mg N m-2 day-1 respectively. Pelagic N fixation is much higher than has been reported elsewhere for oligotrophic lakes, and is more important than previously thought, comprising ~ 75% of N inputs to one lake. Benthic N fixation is lower than has been reported for other oligotrophic systems, and is roughly equivalent to N inputs from atmospheric deposition on an areal basis (~25 mg N m-2 year-1). On the landscape scale, N fixation in lakes roughly equal that in terrestrial ecosystems in this Arctic region. Benthic N fixation generally appears to have a saturating response to light availability within individual lakes, but light does not explain variation in benthic N fixation across lakes or years. Whole-lake fertilization and laboratory experiments indicate that P input stimulates benthic N fixation while N input suppresses N fixation when N is added either alone or in conjunction with P in Redfield proportion. Snails at ambient density cause a small decline in benthic N fixation (0.85 - 1.8% reduction over the summer). These patterns are corroborated in the landscape: lakes on younger surfaces have higher P, more snails, and higher rates of N-fixation than lakes on older surfaces. (Abstract).
Author: Gretchen Maria Gettel
Publisher:
ISBN:
Category :
Languages : en
Pages : 338
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Book Description
Biological nitrogen (N) fixation of atmospheric N2 by free-living cyanobacteria in aquatic environments is common, and in many ecosystems, it can account for a significant portion of the biologically available N inputs. Although N fixation can compensate for N limitation, N limitation is maintained over relatively long time scales in many oligotrophic lake ecosystems. This dissertation examines the importance of benthic and pelagic N fixation in the N economies of oligotrophic lakes in arctic Alaska (Chapter 1) and examines nutrient, light, and grazer controls on benthic N fixation (Chapters 2 and 3). Both benthic and pelagic N fixation are prevalent in many lakes across the Alaskan arctic landscape, ranging from 0.12 - 1.5 mg N m-2 day-1 and 0 - 2.56 mg N m-2 day-1 respectively. Pelagic N fixation is much higher than has been reported elsewhere for oligotrophic lakes, and is more important than previously thought, comprising ~ 75% of N inputs to one lake. Benthic N fixation is lower than has been reported for other oligotrophic systems, and is roughly equivalent to N inputs from atmospheric deposition on an areal basis (~25 mg N m-2 year-1). On the landscape scale, N fixation in lakes roughly equal that in terrestrial ecosystems in this Arctic region. Benthic N fixation generally appears to have a saturating response to light availability within individual lakes, but light does not explain variation in benthic N fixation across lakes or years. Whole-lake fertilization and laboratory experiments indicate that P input stimulates benthic N fixation while N input suppresses N fixation when N is added either alone or in conjunction with P in Redfield proportion. Snails at ambient density cause a small decline in benthic N fixation (0.85 - 1.8% reduction over the summer). These patterns are corroborated in the landscape: lakes on younger surfaces have higher P, more snails, and higher rates of N-fixation than lakes on older surfaces. (Abstract).
Author: John E. Hobbie
Publisher: Oxford University Press
ISBN: 0199360138
Category : Science
Languages : en
Pages : 354
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Book Description
In this edition of the Long Term Ecological Research Network series, editors John Hobbie and George Kling and 58 co-authors synthesize the findings from the NSF-funded Arctic LTER project based at Toolik Lake, Alaska, a site that has been active since the mid-1970s. The book presents research on the core issues of climate-change science in the treeless arctic region of Alaska. As a whole, it examines both terrestrial and freshwater-aquatic ecosystems, and their three typical habitats: tundra, streams, and lakes. The book provides a history of the Toolik Lake LTER site, and discusses its present condition and future outlook. It features contributions from top scientists from many fields, creating a multidisciplinary survey of the Alaskan arctic ecosystem. Chapter topics include glacial history, climatology, land-water interactions, mercury found in the Alaskan arctic, and the response of these habitats to environmental change. The final chapter predicts the consequences that arctic Alaska faces due to global warming and climate change, and discusses the future ecology of the LTER site in the region. Alaska's Changing Arctic is the definitive scientific survey of the past, present, and future of the ecology of the Alaskan arctic.
Author: Cody R. Johnson
Publisher:
ISBN:
Category : Freshwater productivity
Languages : en
Pages : 238
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Book Description
"In lakes, fish and zooplankton can be both sources and sinks of nitrogen (N) and phosphorus (P) through the consumption of organic N and P, and subsequent excretion of bioavailable inorganic forms. These source/sink dynamics, known as consumer-driven nutrient recycling (CNR), may, in turn, control the availability of potentially limiting nutrients for algal primary production. In this dissertation I investigate the importance and controls of CNR as a source of inorganic N and P for primary production (Chapter 2). I then examine zooplankton CNR as a mechanism for increasing nutrient mean resident time (MRT) in the mixed layer of lakes (Chapter 3). Finally, I assess whether zooplankton communities dominated by different taxa can affect N versus P deficient conditions for phytoplankton production through differential N and P recycling rates (Chapter 4). Direct excretion of N and P by fish communities was modest in arctic lakes, and accounted for
Author: J. M. Tiedje
Publisher:
ISBN:
Category : Cyanobacteria
Languages : en
Pages : 35
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Book Description
Author: Vera Alexander
Publisher:
ISBN:
Category : Nitrogen
Languages : en
Pages : 120
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Book Description
Author: Moshe Doron
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The chemical variation between sites was significant also showing a seasonal change. Analysis of nifD clone libraries revealed a diazotrophic community with low diversity that was dominated by filamentous heterocystous cyanobacteria (order Nostocales). Microscopy and nutrient patterns showed these blooms were episodic, possibly due to availability of P relative to N, and that each bloom was influenced by different parameters, with the later blooms depending on the outcome of those prior. The results of this study documented the potential for N2 fixation to transform the lake into a N source to downstream systems, but further study is needed to determine the role of diazotrophs in the formation of algal bloom events.
Author: American Geophysical Union. Joint Assembly
Publisher:
ISBN:
Category : Geophysics
Languages : en
Pages : 588
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Book Description
Author: F Stuart Chapin III
Publisher: Springer Science & Business Media
ISBN: 0387216634
Category : Science
Languages : en
Pages : 449
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Book Description
Features review questions at the end of each chapter; Includes suggestions for recommended reading; Provides a glossary of ecological terms; Has a wide audience as a textbook for advanced undergraduate students, graduate students and as a reference for practicing scientists from a wide array of disciplines
Author: Reinhard Pienitz
Publisher: Springer Science & Business Media
ISBN: 1402021259
Category : Science
Languages : en
Pages : 579
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Book Description
Concerns about the effects of global climate change have focused attention on the vulnerability of circumpolar regions. This book offers a synthesis of the spectrum of techniques available for generating long-term environmental records from circumpolar lakes.
Author: Steven P. Millard
Publisher: Springer Science & Business Media
ISBN: 1461484561
Category : Computers
Languages : en
Pages : 305
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Book Description
This book describes EnvStats, a new comprehensive R package for environmental statistics and the successor to the S-PLUS module EnvironmentalStats for S-PLUS (first released in 1997). EnvStats and R provide an open-source set of powerful functions for performing graphical and statistical analyses of environmental data, bringing major environmental statistical methods found in the literature and regulatory guidance documents into one statistical package, along with an extensive hypertext help system that explains what these methods do, how to use these methods, and where to find them in the environmental statistics literature. EnvStats also includes numerous built-in data sets from regulatory guidance documents and the environmental statistics literature. This book shows how to use EnvStats and R to easily: * graphically display environmental data * plot probability distributions * estimate distribution parameters and construct confidence intervals on the original scale for commonly used distributions such as the lognormal and gamma, as well as do this nonparametrically * estimate and construct confidence intervals for distribution percentiles or do this nonparametrically (e.g., to compare to an environmental protection standard) * perform and plot the results of goodness-of-fit tests * compute optimal Box-Cox data transformations * compute prediction limits and simultaneous prediction limits (e.g., to assess compliance at multiple sites for multiple constituents) * perform nonparametric estimation and test for seasonal trend (even in the presence of correlated observations) * perform power and sample size computations and create companion plots for sampling designs based on confidence intervals, hypothesis tests, prediction intervals, and tolerance intervals * deal with non-detect (censored) data * perform Monte Carlo simulation and probabilistic risk assessment * reproduce specific examples in EPA guidance documents EnvStats combined with other R packages (e.g., for spatial analysis) provides the environmental scientist, statistician, researcher, and technician with tools to “get the job done!”
