Publications

Decadal-scale changes in groundwater quality were evaluated by the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Samples of groundwater collected from wells during 1988-2000 - a first sampling event representing the decade ending the 20th century - were compared on a pair-wise basis to samples from the same wells collected during 2001-2010 - a second sampling...

Throughout the 20th century, the Greater Everglades Ecosystem of south Florida was greatly altered by human activities. Construction of water-control structures and facilities altered the natural hydrologic patterns of the south Florida region and consequently impacted the coastal ecosystem. Restoration of the Greater Everglades Ecosystem is guided by the Comprehensive Everglades...

Statistical analyses were conducted for six water-quality constituents measured at 371 surface-water-quality stations during water years 1998-2009 to determine changes in concentrations over time. This study examined year-round concentrations of total dissolved solids, dissolved nitrite plus nitrate, dissolved phosphorus, total phosphorus, and total nitrogen; concentrations of dissolved...

In the United States, new regulatory restrictions have been placed on the use of some second-generation anticoagulant rodenticides. This action may be offset by expanded use of first-generation compounds (e.g., diphacinone; DPN). Single-day acute oral exposure of adult Eastern screech-owls (Megascops asio) to DPN evoked overt signs of intoxication, coagulopathy, histopathological lesions...

A comprehensive molecular phylogenetic analysis of the family Thamnophilidae indicated that the genus Myrmotherula is not monophyletic. The clade composed of M. guttata and M. hauxwelli is only distantly related to other members of the genus and should be removed from Myrmotherula. The phenotypic distinctiveness of the clade argues against merging it with its sister group Thamnomanes and...

Methylmercury chloride and seleno-L-methionine were injected separately or in combinations into the fertile eggs of mallards (Anas platyrhynchos), chickens (Gallus gallus), and double-crested cormorants (Phalacrocorax auritus), and the incidence and types of teratogenic effects were recorded. For all three species,selenomethionine alone caused more deformities than did methylmercury...

The release of animals to reestablish an extirpated population is a decision problem that is often attended by considerable uncertainty about the probability of success. Annual releases of captive-reared juvenile Whooping Cranes (Grus americana) were begun in 1993 in central Florida, USA, to establish a breeding, non-migratory population. Over a 12-year period, 286 birds were released...

Inbreeding depression is frequently a concern of managers interested in restoring endangered species. Decisions to reduce the potential for inbreeding depression by balancing genotypic contributions to reintroduced populations may exact a cost on long-term demographic performance of the population if those decisions result in reduced numbers of animals released and/or restriction of...

Data augmentation (DA) is a flexible tool for analyzing closed and open population models of capture-recapture data, especially models which include sources of hetereogeneity among individuals. The essential concept underlying DA, as we use the term, is based on adding "observations" to create a dataset composed of a known number of individuals. This new (augmented) dataset, which...

No abstract available.

Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperatures increase, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is important to predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), and pyrosequencing...

In situ chemical oxidation (ISCO) treatment with sodium permanganate, an electrically conductive oxidant, provides a strong electrical signal for tracking of injectate transport using time series geophysical surveys including direct current (DC) resistivity and electromagnetic (EM) methods. Effective remediation is dependent upon placing the oxidant in close contact with the contaminated...