2009 LTER All Scientists Meeting - ARC

Determining organic matter sources to CH4 production and bubbling from Alaskan lakes using stable isotopes and radiocarbon ages

Laura Brosius — Tue, 01 Sep 2009 00:46:24 +0000

Poster Number:

363

Presenter/Primary Author:

Laura Brosius

Co-Authors:

Katey Walter

Co-Authors:

Jeff Chanton

Methane production in Siberian thaw lakes is estimated to be 3.8 Tg CH4 yr -1. When entered into global models, this estimate increases northern wetland CH4 emissions (<6-40 Tg CH4 yr -1) by 10-63% (Walter et al 2006). Methane release of this magnitude from Siberian and other northern lakes, such as those in Alaska, may be linked to the rich carbon resources available to sediment-dwelling methanogens.

Student Poster:

Yes

Arctic LTER: Goals and Results

John Hobbie — Mon, 31 Aug 2009 20:38:57 +0000

Poster Number:

347

Presenter/Primary Author:

John Hobbie

Co-Authors:

George Kling

Co-Authors:

Chris Luecke

Co-Authors:

Gus Shaver

Co-Authors:

Anne Giblin

Co-Authors:

Donie Bret-Harte

The goal of the Arctic LTER is to predict the future ecological characteristics of Arctic Alaska based upon our knowledge of the controls of ecosystem structure and function as exerted by physical setting and geologic factors, climatic factors, biotic factors, and the changes in fluxes of water and materials from land to water.

Dynamics of Water-Stable Soil Aggregates in Arctic Soils

Rodney Simpson — Mon, 31 Aug 2009 18:57:16 +0000

Poster Number:

336

Presenter/Primary Author:

Rodney Simpson

Co-Authors:

John C. Moore

Co-Authors:

Johan Six

Arctic warming has been linked to changes in carbon cycling in this region. Cold temperatures and anoxic conditions in the Arctic inhibit microbial activity, lowering decomposition rates. As a result mineralization rates are low, resulting in nitrogen-limited-system, further reducing biological activity. Evidence has shown that eliminating this constraint on nutrient availability results in a vegetation shift and loss of soil carbon; however, the mechanisms behind soil carbon loss are not understood.

Student Poster:

Yes

Ecosystem change in the Arctic: a 30-year record of geochemical transformations in Toolik Lake

George Kling — Mon, 31 Aug 2009 16:06:26 +0000

Poster Number:

324

Presenter/Primary Author:

George Kling

Co-Authors:

Keller, Katy

Co-Authors:

Kipphut, George

Co-Authors:

Bettez, Neil

Co-Authors:

Giblin, Anne

Co-Authors:

Hobbie, John

Despite substantial changes in climate, sea-ice and glacier extent, and vegetation in much of the Arctic, the area near Toolik Lake, Alaska has experienced no significant trends of increasing temperature, altered precipitation, or increasing active-layer thaw depth. There has been, however, a near doubling of alkalinity in Toolik Lake since 1975 and increases in alkalinity in many lakes of all depths and sizes in the surrounding area. Lake monitoring indicates that in-lake processes such as sulfate or nitrate reduction cannot account for these alkalinity increases.

MIRADA-LTERS

Linda Amaral-Zettler — Mon, 31 Aug 2009 15:45:14 +0000

Poster Number:

323

Presenter/Primary Author:

Linda Amaral-Zettler

Co-Authors:

McCliment, Elizabeth

Co-Authors:

Huse, Susan

The MIRADA project was launched in the fall of 2007 to establish a Microbial Biodiversity Survey and Inventory across all 13 of the major aquatic (marine and freshwater) Long Term Ecological Research (LTER) sites in the NSF US LTER Program. The long-term objective of our study is to document and describe baseline diversity and relative abundance data for both common and rare members of microbial communities and to relate this diversity to the underlying physical and chemical environment.

Spatial and Temporal Patterns of Bacterial Communities in Toolik Lake

Sarah Barbrow — Mon, 31 Aug 2009 13:56:02 +0000

Poster Number:

318

Presenter/Primary Author:

Sarah Barbrow

Co-Authors:

George Kling

Co-Authors:

Byron Crump

Much is known about the spatial and temporal distribution of macro-organisms and their activity rates. However, little is known about the spatial variability of microbial communities in lakes. In this study, we examined the spatial variability in both bacterial community composition and activity rates in Toolik Lake, Alaska. Community composition was characterized using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified rDNA, and activity rates were measured by uptake rates of 14C-leucine.

Student Poster:

Yes

Biological attributes in streams along a glacial chronosequence, North Slope, Alaska

Heidi Rantala — Fri, 28 Aug 2009 15:29:32 +0000

Poster Number:

295

Presenter/Primary Author:

Heidi Rantala

Co-Authors:

Parker, Stephanie

Co-Authors:

Huryn, Alexander

The north slope of the Brooks Range has been glaciated several times since the Late Tertiary, resulting in a landscape with glacial sediments of various ages (modern to ca. 2 million years old) in close proximity. We used space as a substitute for time to investigate how terrain age affects biological attributes of streams in the Toolik Lake region of Arctic Alaska. Similar studies have been limited to successional sequences of streams on terrains deglaciated for up to only 200 years. We extended this model to streams draining terrains that have been deglaciated for up to ca.

Student Poster:

Yes

Environmental Influences on the Genetic Diversity of Arctic Stream Bacterial Communities

Julia Larouche — Fri, 28 Aug 2009 12:34:44 +0000

Poster Number:

292

Presenter/Primary Author:

Julia Larouche

Co-Authors:

William Breck Bowden

Co-Authors:

Rosanna Giordano

Co-Authors:

Michael B. Flinn

Microbes are of critical importance but are a poorly understood component of arctic stream ecosystems. They are responsible for recycling organic matter and regenerating nutrients that are essential to the food webs of aquatic ecosystems. We tested the hypothesis that differences in highly contrasting parent lithologies (non-carbonate and ultramafic), stream habitat (sediments and rocks), and stream biogeochemistry influence the structure of bacterial biofilm communities in arctic streams.

Student Poster:

Yes

Contest Result:

2nd Honorable Mention

First-year effects of tundra fire on benthic macroinvertebrate communities in streams on the North Slope, Alaska

Angela Allen — Thu, 06 Aug 2009 00:26:55 +0000

Poster Number:

201

Presenter/Primary Author:

Angela Allen

Co-Authors:

B.J. Peterson

Co-Authors:

A.D. Huryn

Co-Authors:

E.B. Schuett

Co-Authors:

S.M. Parker

Co-Authors:

G.W. Kling

Post-fire nutrient enrichment is known to affect benthic macroinvertebrate assemblages and stream food webs in forested regions, but little is known about the impact of tundra fires. The 2007 Anaktuvuk River fire (North Slope, Alaska), the largest recorded tundra fire (≈1,000 km²), provided an opportunity to study the first-year effects of a tundra fire on stream communities. We predicted that a tundra fire would increase inorganic nutrient inputs to streams, thereby increasing primary production and in turn, increasing abundance and biomass of benthic macroinvertebrates.

Student Poster:

Yes

Twenty year record of vegetation change from long-term plots in Alaskan tundra

William Gould — Tue, 04 Aug 2009 16:11:05 +0000

Poster Number:

197

Presenter/Primary Author:

William Gould

Co-Authors:

Joel A. Mercado Díaz

Co-Authors:

Jess K. Zimmerman

Twenty year record of vegetation change from long-term plots in Alaskan tundra
William A. Gould¹, Joel A. Mercado Diaz^1,2, Jess K. Zimmerman²
1. USDA Forest Service, International Institute of Tropical Forestry, Río Piedras PR,
2. University of Puerto Rico, Río Piedras, PR