Thomas H. Johengen

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In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with(More)
Hypoxic conditions, defined as dissolved oxygen (DO) concentrations below 2 mg/L, are a regular summertime occurrence in Lake Erie, but the spatial extent has been poorly understood due to sparse sampling. We use geostatistical kriging and conditional realizations to provide quantitative estimates of the extent of hypoxia in the central basin of Lake Erie(More)
We propose the use of Bayesian hierarchical/multilevel ratio approach to estimate the annual riverine phosphorus loads in the Saginaw River, Michigan, from 1968 to 2008. The ratio estimator is known to be an unbiased, precise approach for differing flow-concentration relationships and sampling schemes. A Bayesian model can explicitly address the uncertainty(More)
The Alliance for Coastal Technologies (ACT) has been established to support innovation and to provide the information required to select the most appropriate tools for studying and monitoring coastal and ocean environments. ACT is a consortium of nationally prominent ocean science and technology institutions and experts who provide credible performance data(More)
Hydrogen peroxide (H 2 O 2) has been suggested to influence cyanobacterial community structure and toxicity. However, no study has investigated H 2 O 2 concentrations in freshwaters relative to cyanobacterial blooms when sources and sinks of H 2 O 2 may be highly variable. For example, photochemical production of H 2 O 2 from chromophoric dissolved organic(More)
Common ways to quantify watershed nutrient loads include estimating the annual or seasonal loads using simple relations between discharge and load, such as the ratio estimator, and fitting complex nutrient transport models to the observed concentrations. The former approach produces quite uncertain estimates even at low temporal resolution, when based on(More)
Oligotyping is a computational method used to increase the resolution of marker gene microbiome studies. Although oligotyping can distinguish highly similar sequence variants, the resulting units are not necessarily phylogenetically and ecologically informative due to limitations of the selected marker gene. In this perspective, we examine how oligotyping(More)
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