Mulhollem J.J.,Kaskaskia Biological Station |
Mulhollem J.J.,University of Illinois at Urbana - Champaign |
Mulhollem J.J.,Vermont Agency of Natural Resources |
Colombo R.E.,Eastern Illinois University |
And 2 more authors.
Aquatic Sciences | Year: 2016
Numerous simulation studies have considered the effects of impending climate change on lakes. Predictive models exist for the responses of a multitude of variables to a warmer climate, and potential effects on food webs and ecosystem functions. Although these predictions are numerous, there is a need for manipulative experiments testing for the effects of warming on actual lake systems. We used power plant lakes across the central Midwestern US as a substitute for future climate change effects. These treatment lakes receive heated effluent and are typically 2–6 °C warmer than other regional lakes. We collected data from 1997 to 2010 on a number of abiotic and biotic variables from three of these treatment lakes and six control lakes that were of similar size and location but did not have an artificial thermal regime. Phosphorus and phytoplankton concentrations were similar between treatment groups, although treatment lakes had greater phosphorus and less phytoplankton in September. No differences existed in turbidity (measured as Secchi depth transparency). Zooplankton were less abundant in treatment lakes than in control lakes throughout our sampling period (May–October), with differences in cladocerans driving this disparity. There was evidence of earlier spawning of gizzard shad (Dorosoma cepedianum) due to the warmer temperature regime, but not for bluegill (Lepomis macrochirus). Average sizes of juvenile bluegill were larger in warmed systems in July and August. Juvenile largemouth bass (Micropterus salmoides) were larger in heated systems in June, but no differences existed in July or August. Growth of adult largemouth bass was greater in systems with a warmer thermal regime. Our results provide insights into patterns that can be expected in the future, and may be used to further understand the wide-reaching implications of climate change. © 2016 Springer International Publishing
Oswald E.M.,University Corporation for Atmospheric Research |
Dupigny-Giroux L.-A.,University of Vermont |
Leibensperger E.M.,Center for Earth and Environmental Science |
Poirot R.,Vermont Agency of Natural Resources |
Merrell J.,Vermont Agency of Natural Resources
Atmospheric Environment | Year: 2015
The goal of this study is to better understand the linkages between the climate system and surface-level ozone concentrations in the Northeastern U.S. We focus on the regularity of observed high ozone concentrations between May 15 and August 30 during the 1993-2012 period. The first portion of this study establishes relationships between ozone and meteorological predictors. The second examines the linkages between ozone and large-scale teleconnections within the climate system. Statistical models for each station are constructed using a combination of Correlation Analysis, Principal Components Analysis and Multiple Linear Regression. In general, the strongest meteorological predictors of ozone are the frequency of high temperatures and precipitation and the amount of solar radiation flux. Statistical models of meteorological variables explain about 60-75% of the variability in the annual ozone time series, and have typical error-to-variability ratios of 0.50-0.65. Teleconnection patterns such as the Arctic Oscillation, Quasi-Biennial Oscillation and Pacific Decadal Oscillation are best linked to ozone in the region. Statistical models of these patterns explain 40-60% of the variability in the ozone annual time series, and have a typical error-to-variability ratio of 0.60-0.75. © 2015 The Authors.
Kline M.,Vermont Agency of Natural Resources |
Cahoon B.,Vermont Agency of Natural Resources
Journal of the American Water Resources Association | Year: 2010
The Vermont Agency of Natural Resources' current strategy for restoring aquatic habitat, water quality, and riparian ecosystem services is the protection of fluvial geomorphic-based river corridors and associated wetland and floodplain attributes and functions. Vermont has assessed over 1,350 miles of stream channels to determine how natural processes have been modified by channel management activities, corridor encroachments, and land use / land cover changes. Nearly three quarters of Vermont field-assessed reaches are incised limiting access to floodplains and thus reducing important ecosystem services such as flood and erosion hazard mitigation, sediment storage, and nutrient uptake. River corridor planning is conducted with geomorphic data to identify opportunities and constraints to mitigating the effects of physical stressors. Corridors are sized based on the meander belt width and assigned a sensitivity rating based on the likelihood of channel adjustment due to stressors. The approach adopted by Vermont is fundamentally based on restoring fluvial processes associated with dynamic equilibrium, and associated habitat features. Managing toward fluvial equilibrium is taking hold across Vermont through adoption of municipal fluvial erosion hazard zoning and purchase of river corridor easements, or local channel and floodplain management rights. These tools signify a shift away from primarily active management approaches of varying success that largely worked against natural river form and process, to a current community-based, primarily passive approach to accommodate floodplain reestablishment through fluvial processes. © 2010 American Water Resources Association.
Colleran B.P.,Vermont Agency of Natural Resources |
Goodall K.E.,Vermont Agency of Natural Resources
Invasive Plant Science and Management | Year: 2014
The objective of this article is to identify growth patterns of Japanese knotweed propagules distributed by high-water events. Along four river systems, we collected and measured Japanese knotweed propagules that had been distributed by flooding approximately 1 yr earlier. Results indicate that the size of the emergent shoot may be determined by the extent of underground growth late in the growing season, although initially it is linked to the size of the propagule. Our results show that 70% of new plants originated from rhizome fragments, and 30% from stems. This proportion is similar to regeneration rates shown in laboratory studies. We suggest that the best way to prevent the spread of Japanese knotweed along rivers is to focus control efforts on those stands most susceptible to erosion and propagule dispersal. We also suggest that an early detection and rapid response management approach can be effectively utilized to eradicate these propagules, and effectively suppress the spread of Japanese knotweed. Our data-collection method also provides evidence that control of newly distributed propagules can be effectively accomplished without the use of herbicides or heavy mechanical tools. © 2013 Weed Science Society of America.
Mathon B.R.,University of Vermont |
Rizzo D.M.,University of Vermont |
Kline M.,Vermont Agency of Natural Resources |
Alexander G.,Vermont Agency of Natural Resources |
And 3 more authors.
Journal of the American Water Resources Association | Year: 2013
Watershed managers often use physical geomorphic and habitat assessments in making decisions about the biological integrity of a stream, and to reduce the cost and time for identifying stream stressors and developing mitigation strategies. Such analysis is difficult since the complex linkages between reach-scale geomorphic and habitat conditions, and biological integrity are not fully understood. We evaluate the effectiveness of a generalized regression neural network (GRNN) to predict biological integrity using physical (i.e., geomorphic and habitat) stream-reach assessment data. The method is first tested using geomorphic assessments to predict habitat condition for 1,292 stream reaches from the Vermont Agency of Natural Resources. The GRNN methodology outperforms linear regression (69% vs. 40% classified correctly) and improves slightly (70% correct) with additional data on channel evolution. Analysis of a subset of the reaches where physical assessments are used to predict biological integrity shows no significant linear correlation, however the GRNN predicted 48% of the fish health data and 23% of macroinvertebrate health. Although the GRNN is superior to linear regression, these results show linking physical and biological health remains challenging. Reasons for lack of agreement, including spatial and temporal scale differences, are discussed. We show the GRNN to be a data-driven tool that can assist watershed managers with large quantities of complex, nonlinear data. © 2013 American Water Resources Association492 April 2013 10.1111/jawr.12030 Technical Paper Technical Papers © 2013 American Water Resources Association.