Physical Sciences and Mathematics | Open Access Articles

Determining Sources Of Nitrate In The Semi-Arid Rio Grande Using Nitrogen And Oxygen Isotopes, Diego Alberto Sanchez Hernandez

Masters Theses

The Rio Grande, a semi-arid river in the American Southwest, is a major source of surface water for agriculture and drinking supplies in New Mexico and Texas. In addition to increasing salinity, considerable increases of NO₃^- [nitrate] have been observed in the semi-arid portion of the Rio Grande. It is possible that elevated water salinity inhibits denitrification on irrigated fields and, thus, fails to mediate excess nutrient load from anthropogenic activities. Therefore, two major goals of this project were to 1) characterize and quantify major NO₃^- sources, and 2) assess whether elevated water salinity affects microbial …

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Oceanic-Atmospheric And Hydrologic Variability In Long Lead-Time Forecasting, Abdoul Aziz Oubeidillah

Doctoral Dissertations

Water managers throughout the world are challenged with managing scarce resources and therefore rely heavily on forecasts to allocate and meet various water demands. The need for improved streamflow and snowpack forecast models is of the utmost importance. In this research, the use of oceanic and atmospheric variables as predictors was investigated to improve the long lead-time (three to nine months) forecast of streamflow and snowpack. Singular Value Decomposition (SVD) analysis was used to identify a region of Pacific and Atlantic Ocean SSTs and a region of 500 mbar geopotential height (Z500mb) that were teleconnected with streamflow and snowpack. The …

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Niche Of Harmful Alga Aureococcus Anophagefferens Revealed Through Ecogenomics, Christopher Gobler, Dianna Berry, Sonya Dyhrman, Steven Wilhelm

Microbiology Publications and Other Works

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. …

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Aquatic Habitat Mapping Within The Obed Wild And Scenic River For Threatened And Endangered Species Habitat Delineation, Joseph Ross Candlish

Masters Theses

There is a need to define a more efficient and accurate approach to aquatic habitat mapping. Traditional approaches have focused on intense biological/non-biological sampling and observation analysis within specific and restrained scales. Therefore, an underwater video mapping system (UVMS) has been developed in efforts to identify federally protected aquatic species’ habitats within the Obed Wild and Scenic River (OBRI). The UVMS kayak apparatus provides georeferenced video footage correlated with GPS (global positioning systems) for GIS (geographic information systems) mapping applications. Based on its fluvial and geomorphological trends, OBRI was dissected quantitatively and integrated into databases for species-specific GIS habitat queries. …

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The Construction And Analysis Of Marker Gene Libraries, S.M. Short, F. Chen, Steven Wilhelm

Microbiology Publications and Other Works

Marker genes for viruses are typically amplified from aquatic samples to determine whether specific viruses are present in the sample, or to examine the diversity of a group of related viruses. In this chapter, we will provide an overview of common methods used to amplify, clone, sequence, and analyze virus marker genes, and will focus our discussion on viruses infecting algae, bacteria, and heterotrophic flagellates. Within this chapter, we endeavor to highlight critical aspects and components of these methods. To this end, instead of providing a detailed experimental protocol for each of the steps involved in examining virus marker gene …

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Determining Rates Of Virus Production In Aquatic Systems By The Virus Reduction Approach,, M.G. Weinbauer, J.M. Rowe, Steven Wilhelm

Microbiology Publications and Other Works

The reduction approach to assess virus production and the prokaryotic mortality by viral lysis stops new infection by reducing total virus abundance (and thus virus–host contacts). This allows for easy enumeration of viruses that originate from lysis of already infected cells due to the decreased abundance of free virus particles. This reoccurrence can be quantified and used to assess production and cell lysis rates. Several modifications of the method are presented and compared. The approaches have great potential for elucidating trends in virus production rates as well as for making generalized estimates of the quantitative effects of viruses on marine …

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Identifying The Source Of Unknown Microcystin Genes And Predicting Microcystin Variants By Comparing Genes Within Uncultured Cyanobacterial Cells, C.J. Allender, G.R. Lecleir, J.M. Rinta-Kanto, R.L. Small, M.F. Satchwell, G.L. Boyer, Steven Wilhelm

Microbiology Publications and Other Works

While multiple phylogenetic markers have been used in the culture independent study of microcystin producing cyanobacteria, in only a few instances have multiple markers been studied within individual cells, and in all cases these studies have been conducted with cultured isolates. Here, we isolate and evaluate large DNA fragments (> 6 kb) encompassing two genes involved in microcystin biosynthesis (mcyA2 and mcyB1) and use them to identify the source of gene fragments found in water samples. Further investigation of these gene loci from individual cyanobacterial cells allowed for improved analysis of the genetic diversity within microcystin producers as …

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Actinorhodopsin Genes Discovered Diverse In Freshwater Habitats And Among Cultivated Actinobacteria, A.K. Sharma, K. Sommerfeld, G.S. Bullerjahn, A.R. Matteson, Steven Wilhelm, J. Jezbera, U. Brandt, W.F. Doolittle, M.W. Hahn

Microbiology Publications and Other Works

Microbial rhodopsins are membrane proteins that utilize a retinal chromophore to harvest sunlight for energetic and photosensory functions. Recently, a group of novel rhodopsin sequences named ‘actinorhodopsins’ (ActRs) was hypothesized to exist among uncultured planktonic Actinobacteria. ActRs were discovered by mining metagenomic data obtained during the Venter Institute’s Global Ocean Sampling expedition, from a hypersaline lagoon, two estuaries and a freshwater lake. On the basis of these findings, and many studies that show Actinobacteria are common inhabitants of lakes, we predicted that ActR genes would likely be present in other freshwater habitats and among the genomes of cultivated Actinobacteria …

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The Effects Of Increased Pco2 And Temperature On The North Atlantic Spring Bloom: I. The Phytoplankton Community And Biogeochemical Response, Y. Feng, C.E. Hare, K. Leblanc, J.M. Rose, Y Zhang, G.R. Ditullio, P. Lee, Steven Wilhelm, J.M. Rowe, J. Sun, N. Nemcek, C. Gueguen, U. Passow, I. Benner, C. Brown, D.A. Hutchins

Microbiology Publications and Other Works

ABSTRACT: The North Atlantic spring bloom is one of the largest annual biological events in the ocean, and is characterized by dominance transitions from siliceous (diatoms) to calcareous (coccolithophores) algal groups. To study the effects of future global change on these phytoplankton and the biogeochemical cycles they mediate, a shipboard continuous culture experiment (Ecostat) was conducted in June 2005 during this transition period. Four treatments were examined: (1) 12°C and 390 ppm CO₂ (ambient control), (2) 12°C and 690 ppm CO₂ (high pCO₂), (3) 16°C and 390 ppm CO₂ (high temperature), and (4) 16°C and …

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Effects Of Increased Pco2 And Temperature On The North Atlantic Spring Bloom: Iii. Dimethylsulfoniopropionate, P.A. Lee, J.R. Rudisill, A.R. Neeley, D.A. Hutchins, Y. Feng, C.E. Hare, K. Leblanc, J.M. Rose, Steven Wilhelm, J.M. Rowe, G.R. Ditullio

Microbiology Publications and Other Works

The CLAW hypothesis argues that a negative feedback mechanism involving phytoplankton-derived dimethylsulfoniopropionate (DMSP) could mitigate increasing sea surface temperatures that result from global warming. DMSP is converted to the climatically active dimethylsulfide (DMS), which is transferred to the atmosphere and photochemically oxidized to sulfate aerosols, leading to increases in planetary albedo and cooling of the Earth’s atmosphere. A shipboard incubation experiment was conducted to investigate the effects of increased temperature and pCO2 on the algal community structure of the North Atlantic spring bloom and their subsequent impact on particulate and dissolved DMSP concentrations (DMSP_p and DMSP_d). Under …

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Distribution Of Calcifying And Silicifying Phytoplankton In Relation To Environmental And Biogeochemical Parameters During The Late Stages Of The 2005 North East Atlantic Spring Bloom, K. Leblanc, C.E. Hare, Y. Feng, G.M. Berg, G.R. Ditullio, A. Neeley, I. Benner, C. Sprengel, A. Beck, S.A. Sanudo-Wilhemy, U. Passow, K. Klinck, J.M. Rowe, Steven Wilhelm, C.W. Brown, D.A. Hutchins

Microbiology Publications and Other Works

The late stage of the North East Atlantic (NEA) spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi), particulate inorganic carbon (PIC) or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively), as well as transparent exopolymer particles (TEP). Results were compared with other studies undertaken in …

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Limnología De Las Lagunas Glaciales En El Páramo Del Chirripó, Costa Rica. (Limnology Of Glacial Lakes In The Chirripó Páramo Of Costa Rica.), Sally P Horn, Kenneth H. Orvis, Kurt A. Haberyan

Geography Publications and Other Works

More than 30 lakes of glacial origin exist within the Chirripó páramo in the Cordillera de Talamanca of Costa Rica. This chapter describes the geomorphic setting and physical and chemical limnology of 19 lakes located between 3450-3570 m elevation in the upper basins of five glaciated valleys. All lakes are clear, dilute, and apparently polymictic. Water chemistry data from 1998, 2000, and 2001 are similar from lake to lake and year to year, and are consistent with sparse prior measurements between 1966 and 1991. However, the lake water temperatures we have measured are much higher than those reported by earlier …

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Registros De Sedimentos Lacustres De La Vegetación Del Holoceno Y Historia Del Fuego En El Páramo De Costa Rica. (Lake-Sediment Records Of Holocene Vegetation And Fire History In The Costa Rican Páramos), Sally P Horn, Brandon L. League

Geography Publications and Other Works

We examined pollen, pteridophyte (ferns and fern-allies) spores, and charcoal in a 5.6 m long sediment core from Lago de las Morrenas 1, and charcoal in a 1.1 m long sediment core from Lago Chirripó, to reconstruct postglacial vegetation and fire history in the Chirripó páramo. Lago de las Morrenas 1, the largest lake in the Valle de las Morrenas of Chirripó National Park, is presently surrounded by treeless páramo vegetation and has apparently been so since deglaciation approximately 10,000 radiocarbon years ago. Pollen spectra suggest no pronounced changes in vegetation since ice retreat. Pollen percentages for Gramineae and other …

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Full-Text Articles in Physical Sciences and Mathematics

Determining Sources Of Nitrate In The Semi-Arid Rio Grande Using Nitrogen And Oxygen Isotopes, Diego Alberto Sanchez Hernandez

Masters Theses

Oceanic-Atmospheric And Hydrologic Variability In Long Lead-Time Forecasting, Abdoul Aziz Oubeidillah

Doctoral Dissertations

Niche Of Harmful Alga Aureococcus Anophagefferens Revealed Through Ecogenomics, Christopher Gobler, Dianna Berry, Sonya Dyhrman, Steven Wilhelm

Microbiology Publications and Other Works

Aquatic Habitat Mapping Within The Obed Wild And Scenic River For Threatened And Endangered Species Habitat Delineation, Joseph Ross Candlish

Masters Theses

The Construction And Analysis Of Marker Gene Libraries, S.M. Short, F. Chen, Steven Wilhelm

Microbiology Publications and Other Works

Determining Rates Of Virus Production In Aquatic Systems By The Virus Reduction Approach,, M.G. Weinbauer, J.M. Rowe, Steven Wilhelm

Microbiology Publications and Other Works

Identifying The Source Of Unknown Microcystin Genes And Predicting Microcystin Variants By Comparing Genes Within Uncultured Cyanobacterial Cells, C.J. Allender, G.R. Lecleir, J.M. Rinta-Kanto, R.L. Small, M.F. Satchwell, G.L. Boyer, Steven Wilhelm

Microbiology Publications and Other Works

Actinorhodopsin Genes Discovered Diverse In Freshwater Habitats And Among Cultivated Actinobacteria, A.K. Sharma, K. Sommerfeld, G.S. Bullerjahn, A.R. Matteson, Steven Wilhelm, J. Jezbera, U. Brandt, W.F. Doolittle, M.W. Hahn

Microbiology Publications and Other Works

Microbiology Publications and Other Works

Effects Of Increased Pco2 And Temperature On The North Atlantic Spring Bloom: Iii. Dimethylsulfoniopropionate, P.A. Lee, J.R. Rudisill, A.R. Neeley, D.A. Hutchins, Y. Feng, C.E. Hare, K. Leblanc, J.M. Rose, Steven Wilhelm, J.M. Rowe, G.R. Ditullio

Microbiology Publications and Other Works

Microbiology Publications and Other Works

Limnología De Las Lagunas Glaciales En El Páramo Del Chirripó, Costa Rica. (Limnology Of Glacial Lakes In The Chirripó Páramo Of Costa Rica.), Sally P Horn, Kenneth H. Orvis, Kurt A. Haberyan

Geography Publications and Other Works

Registros De Sedimentos Lacustres De La Vegetación Del Holoceno Y Historia Del Fuego En El Páramo De Costa Rica. (Lake-Sediment Records Of Holocene Vegetation And Fire History In The Costa Rican Páramos), Sally P Horn, Brandon L. League

Geography Publications and Other Works