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Helena, MT, United States

Bahls L.,Montana Diatom Collection | Pierce J.,737 Locust | Apfelbeck R.,520 E. 6th Avenue | Olsen L.,Helena National Forest
Phytotaxa | Year: 2013

Relict assemblages of arctic, sub-arctic, and boreal diatoms were found intact in two undisturbed floating-mat fens at 47o north latitude and 1,830 m elevation in the Rocky Mountains of western Montana, USA. The fens support Encyonema droseraphilum sp. nov. and several rare northern/alpine diatom species-including eleven apparent first records for the contiguous United States-and three species of vascular plants that are imperiled in Montana. For many of the diatoms and one of the vascular plants, the fens are at the southern limit of their known distributions in North America. Twentyseven of the 49 diatom taxa in the fens are considered at risk or declining in Germany, and similar ratings appear to be appropriate for these taxa in Montana, especially in light of global warming and human destruction of wetlands. A nearby wetland that has been disturbed by dam-building activities of beaver (Castor canadensis), but not by human landscape alterations, produced a diatom assemblage that contained three times more taxa than the fens but was dominated by common species, primarily Staurosirella pinnata. Our findings illustrate the effects of natural, intermediate disturbance on diatom species composition and underscore the importance of protecting undisturbed aquatic systems for the purpose of conserving rare species and for monitoring environmental change. © 2013 Magnolia Press. Source


Flynn K.F.,520 E. 6th Avenue | Van Liew M.W.,University of Nebraska - Lincoln
Transactions of the ASABE | Year: 2011

Federal and state agencies across the U.S. are currently tasked with Total Maximum Daily Load (TMDL) development to ensure compliance with the Clean Water Act of 1972. In the northwestern part of the country, the TMDL effort is particularly challenging due to the complicated nature of expansive forested watersheds, steep mountainous topography, and orographic precipitation. This is especially true for sediment, which is a primary pollutant of concern. Modeling, in combination with field source assessments, has commonly been used to estimate watershed sediment yields and associated source contributions. However, even with widespread use of these methods, little has been done to evaluate the prediction performance of modeling tools in forested mountainous regions. The purpose of this article is to present an eight-year simulation period (1985-1992) for the 1,709 km 2 Lamar River watershed in Yellowstone National Park where simulated loads from the Soil and Water Assessment Tool (SWAT) were compared with observed suspended sediment discharge data. Based on Nash-Sutcliffe model efficiencies of >0.81 and >0.86 for daily and monthly streamflow, and >0.51 and >0.78 for sediment, our findings suggest that SWAT is suitable for simulation of sediment in mountainous and snowmelt-dominated terrain. Two ancillary lines of evidence were used to support this conclusion: (1) a comparison of simulated landscape sediment yields with that of regional literature studies, and (2) confirmation of simulated landscape and bank erosion source contributions with that of ratios established using radionuclide tracers. © 2011 American Society of Agricultural and Biological Engineers. Source


Flynn K.F.,520 E. 6th Avenue | Suplee M.W.,520 E. 6th Avenue | Chapra S.C.,Tufts University | Tao H.,LimnoTech Inc.
Journal of the American Water Resources Association | Year: 2015

An initial inquiry into model-based numeric nitrogen and phosphorus (nutrient) criteria for large rivers is presented. Field data collection and associated modeling were conducted on a segment of the lower Yellowstone River in the northwestern United States to assess the feasibility of deriving numeric nutrient criteria using mechanistic water-quality models. The steady-state one-dimensional model QUAL2K and a transect-based companion model AT2K were calibrated and confirmed against low-flow conditions at a time when river loadings, water column chemistry, and diurnal indicators were approximately steady state. Predictive simulation was then implemented via nutrient perturbation to evaluate the steady-state and diurnal response of the river to incremental nutrient additions. In this first part of a two-part series, we detail our modeling approach, model selection, calibration and confirmation, sensitivity analysis, model outcomes, and associated uncertainty. In the second part (Suplee et al., 2015) we describe the criteria development process using the tools described herein. Both articles provide a fundamental understanding of the process required to develop site-specific numeric nutrient criteria using models in applied regulatory settings. © 2014 American Water Resources Association. Source


Flynn K.F.,520 E. 6th Avenue | Flynn K.F.,Tufts University | Chapra S.C.,Tufts University | Suplee M.W.,520 E. 6th Avenue
Ecological Modelling | Year: 2013

The lateral distribution of benthic algae in flowing waters is an overlooked but important component of river water-quality management. A number of workers have described the spatially variable structure of bottom algae in the field, yet rarely has it been reproduced using mechanistic models. In this study, we develop a simple numerical model that describes lateral biomass accrual of bottom-attached algae in rivers and illustrate how gradients in light through the water column can be an important consideration in nutrient regulatory management. We then present a comparison of simulated and observed results on the Yellowstone River in the northern United States where the model was applied to compute maximum steady-state biomass. Following calibration to site-specific data, algal simulations yielded satisfactory outcomes with root mean square error and percent bias of 21.8mg chlorophyll am-2 and 51.9%, respectively for four different river transects totaling n=36 observations. The general distribution of periphyton was well-represented. In this regard, we suggest that the tool is useful for management of light-limited rivers where depth varies significantly across the channel. However, accumulations of filamentous algae and confounding effects such as velocity and substratum influence community spatial structure and warrant further investigation with respect to the proposed model. © 2013 Elsevier B.V. Source

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