Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America.

Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide.

Integration of stable carbon isotope, microbial community, dissolved hydrogen gas, and ²HH₂O tracer data to assess bioaugmentation for chlorinated ethene degradation in fractured rocks.

An in situ bioaugmentation (BA) experiment was conducted to understand processes controlling microbial dechlorination of trichloroethene (TCE) in groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. In the BA experiment, an electron donor (emulsified vegetable oil and sodium lactate) and a chloro-respiring microbial consortium were injected into a well in fractured mudstone of Triassic age. Water enriched in ²H was also injected as a tracer of the BA solution, to monitor advective transport processes.

Microbial community composition and endolith colonization at an Arctic thermal spring are driven by calcite precipitation.

Environmental conditions shape community composition. Arctic thermal springs provide an opportunity to study how environmental gradients can impose strong selective pressures on microbial communities and provide a continuum of niche opportunities. We use microscopic and molecular methods to conduct a survey of microbial community composition at Troll Springs on Svalbard, Norway, in the high Arctic.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, , the vent chimney-dwelling mussel, , , a commensal worm of , and the gastropod showed variations in As concentration and in stable isotope (δC and δN) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in , whereas in arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species.

Evidence for iron-mediated anaerobic methane oxidation in a crude oil-contaminated aquifer.

In a methanogenic crude oil contaminated aquifer near Bemidji, Minnesota, the decrease in dissolved CH(4) concentrations along the groundwater flow path, along with the positive shift in δ(13) C(CH) (4) and negative shift in δ(13) C(DIC) , is indicative of microbially mediated CH(4) oxidation. Calculations of electron acceptor transport across the water table, through diffusion, recharge, and the entrapment and release of gas bubbles, suggest that these processes can account for at most 15% of the observed total reduced carbon oxidation, including CH(4) . In the anaerobic plume, the characteristic Fe(III)-reducing genus Geobacter was the most abundant of the microbial groups tested, and depletion of labile sediment iron is observed over time, confirming that reduced carbon oxidation coupled to iron reduction is an important process.