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Relative Changes In Krillabundance Inferred From Antarctic Fur Seal, T. Huang, L. Sun, John M. Stark, Y. Wang, Z. Cheng, Q. Yang, S. Sun Jan 2011

Relative Changes In Krillabundance Inferred From Antarctic Fur Seal, T. Huang, L. Sun, John M. Stark, Y. Wang, Z. Cheng, Q. Yang, S. Sun

John M. Stark

No abstract provided.


Discontinuities In Stream Nutrient Uptake Below Lakesin Mountain Drainage Networks, Michelle A. Baker Jan 2007

Discontinuities In Stream Nutrient Uptake Below Lakesin Mountain Drainage Networks, Michelle A. Baker

Michelle A. Baker

In many watersheds, lakes and streams are hydrologically linked in spatial patterns that influence material transport and retention. We hypothesized that lakes affect stream nutrient cycling via modifications to stream hydrogeomorphology, source‐waters, and biological communities. We tested this hypothesis in a lake district of the Sawtooth Mountains, Idaho. Uptake of NO3− and PO4−3 was compared among 25 reaches representing the following landscape positions: lake inlets and outlets, reaches >1‐km downstream from lakes, and reference reaches with no nearby lakes. We quantified landscape‐scale hydrographic and reach‐scale hydrogeomorphic, source‐water, and biological variables to characterize these landscape positions and analyze relationships to nutrient …


Controls On Nitrogen Cycling In Terrestrial Ecosystems: A Synthetic Analysis Of Literature Data, M. S. Booth, John M. Stark, E. Rastetter Jan 2005

Controls On Nitrogen Cycling In Terrestrial Ecosystems: A Synthetic Analysis Of Literature Data, M. S. Booth, John M. Stark, E. Rastetter

John M. Stark

No abstract provided.


Improving Quantitative Understanding Using Spreadsheet Models, Michelle A. Baker Jan 2003

Improving Quantitative Understanding Using Spreadsheet Models, Michelle A. Baker

Michelle A. Baker

No abstract provided.


Regulation Of Nitric Oxide Emissions From Forest And Rangeland Soils Of Western North America, John M. Stark, D. R. Smart, S. C. Hart, K. A. Haubensak Jan 2002

Regulation Of Nitric Oxide Emissions From Forest And Rangeland Soils Of Western North America, John M. Stark, D. R. Smart, S. C. Hart, K. A. Haubensak

John M. Stark

Nitric oxide (NO) is a relatively short-lived trace gas that reacts with oxygen in the troposphere to produce the air pollutant ozone. It also reacts with water vapor to form nitric and nitrous acids, which acidify precipitation and increase N deposition. Models currently used to predict soil NO fluxes are based on the assumption that NO flux is proportional to the gross rate of nitrification or N mineralization; however, this assumption has not been tested because of the difficulty in measuring gross N-cycling rates in situ. We measured soil NO fluxes, gross and net N-cycling rates, and a variety of …


Ecology Readings From The University Of Wisconsin, Michelle A. Baker Jan 2001

Ecology Readings From The University Of Wisconsin, Michelle A. Baker

Michelle A. Baker

No abstract provided.


Organic Carbon Supply And Metabolism In A Shallow Groundwater Ecosystem, Michelle A. Baker Jan 2000

Organic Carbon Supply And Metabolism In A Shallow Groundwater Ecosystem, Michelle A. Baker

Michelle A. Baker

In groundwater ecosystems, in situ primary production is low, and metabolism depends on organic matter inputs from other regions of the catchment. Heterotrophic metabolism and biogeochemistry in the floodplain groundwater of a headwater catchment (Rio Calaveras, New Mexico, USA) were examined to address the following questions: (1) How do groundwater metabolism and biogeochemistry vary spatially and temporally? (2) What factors influence groundwater metabolism? (3) What is the energy source for groundwater metabolism?


Acetate Retention And Metabolism In Thehyporheic Zone Of A Mountain Stream, Michelle A. Baker Jan 1999

Acetate Retention And Metabolism In Thehyporheic Zone Of A Mountain Stream, Michelle A. Baker

Michelle A. Baker

An in situ acetate injection was used to determine the influence of labile dissolved organic carbon (DOC) availability on microbial respiration in the hyporheic zone of a headwater stream. We added bromide as a conservative tracer and acetate as an organic substrate to the hyporheic zone of Rio Calaveras, New Mexico, via an injection well. Tracer was observed in four of eight capture wells. Three of the four wells showed increases in bromide without concurrent increases in acetate concentration, suggesting 100% acetate retention. One well had 38% acetate retention. Pore velocity and acetate retention were negatively correlated, suggesting hydrologic control …


Foraminiferal Biofacies On A North Coast Fringing Reef (1-75m), Discovery Bay, Jamaica, R. E. Martin, W. D. Liddell Jan 1998

Foraminiferal Biofacies On A North Coast Fringing Reef (1-75m), Discovery Bay, Jamaica, R. E. Martin, W. D. Liddell

W. David Liddell

No abstract provided.


Evidence That Elevated Co2 Leveles And Indirectly Increase Rhizosphere Denitrifier Activity, D. Smart, K. Ritchie, John M. Stark, Bruce Bugbee Jan 1997

Evidence That Elevated Co2 Leveles And Indirectly Increase Rhizosphere Denitrifier Activity, D. Smart, K. Ritchie, John M. Stark, Bruce Bugbee

John M. Stark

No abstract provided.


Mechanisms For Soil Moisture Effects On Activity Of Nitrifying Bacteria, John M. Stark, M. K. Firestone Jan 1995

Mechanisms For Soil Moisture Effects On Activity Of Nitrifying Bacteria, John M. Stark, M. K. Firestone

John M. Stark

Moisture may limit microbial activity in a wide range of environments including salt water, food, wood, biofilms, and soils. Low water availability can inhibit microbial activity by lowering intracellular water potential and thus reducing hydration and activity of enzymes. In solid matrices, low water content may also reduce microbial activity by restricting substrate supply. As pores within solid matrices drain and water films coating surfaces become thinner, diffusion path lengths become more tortuous, and the rate of substrate diffusion to microbial cells declines. We used two independent techniques to evaluate the relative importance of cytoplasmic dehydration versus diffusional limitations in …


Experimental Analysis Of Abrasion And Dissolution Resistance Of Modern Reef-Dwelling Foraminifera: Implications For The Preservation Of Biogenic Carbonate, E. Kotler, R. E. Martin, W. D. Liddell Jan 1992

Experimental Analysis Of Abrasion And Dissolution Resistance Of Modern Reef-Dwelling Foraminifera: Implications For The Preservation Of Biogenic Carbonate, E. Kotler, R. E. Martin, W. D. Liddell

W. David Liddell

No abstract provided.


Microhabitat Analyses Of Silurian Stromatoporoids As Substrata For Epibionts, M. T. Segars, W. D. Liddell Jan 1988

Microhabitat Analyses Of Silurian Stromatoporoids As Substrata For Epibionts, M. T. Segars, W. D. Liddell

W. David Liddell

No abstract provided.


Hard Substrata Community Patterns, 1-120m, North Jamaica, W. D. Liddell, S. L. Ohlhorst Jan 1988

Hard Substrata Community Patterns, 1-120m, North Jamaica, W. D. Liddell, S. L. Ohlhorst

W. David Liddell

No abstract provided.


Back Reef And Fore Reef Analogs In The Pleistocene Of North Jamaica: Implications For Facies Recognition And Sediment Flux In Fossil Reefs, S. K. Boss, W. D. Liddell Jan 1987

Back Reef And Fore Reef Analogs In The Pleistocene Of North Jamaica: Implications For Facies Recognition And Sediment Flux In Fossil Reefs, S. K. Boss, W. D. Liddell

W. David Liddell

No abstract provided.