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Articles 1 - 22 of 22
Full-Text Articles in Life Sciences
Under Ice Photosynthetic Primary Production And Dark Carbon Fixation In A Temperate Freshwater System, Vanessa Cubillos Tellez
Under Ice Photosynthetic Primary Production And Dark Carbon Fixation In A Temperate Freshwater System, Vanessa Cubillos Tellez
Dissertations, Master's Theses and Master's Reports
Ice-covered lakes are vulnerable to environmental change, especially those in the Northern Hemisphere where ice cover is rapidly declining due to global warming. These changes can alter metabolic processes and disrupt carbon cycling driven by primary producers who form the base of the food chain and are key to sustaining ecosystem function. Photosynthetic primary production and dark carbon fixation under the ice in the Keweenaw Waterway, a temperate freshwater system that is ice-covered for ~3 months out of the year, were studied using a carbon isotopic labeling (14C-bicarbonate) technique. Water samples were collected weekly during ice cover and monthly during …
Characterization Of Vernal Pools Across National Parks In The Great Lakes Region, Samantha R. Kurkowski
Characterization Of Vernal Pools Across National Parks In The Great Lakes Region, Samantha R. Kurkowski
Dissertations, Master's Theses and Master's Reports
Vernal pools are small, ephemeral wetlands that become inundated each spring and provide many ecosystem services to the surrounding upland forests. They also provide critical habitat for amphibians and invertebrates, as their temporary nature keeps them free of fish and reduces predator populations. As part of a mapping project, we collected baseline field data on vernal pool characteristics throughout five Great Lakes National Parks: Pictured Rocks National Lakeshore, Sleeping Bear Dunes National Lakeshore, Apostle Islands National Lakeshore, Isle Royale National Park, and Voyagers National Parks. Our goals were to characterize and assess how vernal pools vary within and across the …
Eutrophication On Twin Lakes: Applying A Phosphorus Budget And Shoreline Surveys To Assess Current & Historical Lake Health, Tyler K. Lemahieu
Eutrophication On Twin Lakes: Applying A Phosphorus Budget And Shoreline Surveys To Assess Current & Historical Lake Health, Tyler K. Lemahieu
Dissertations, Master's Theses and Master's Reports
The Twin Lakes system, a series of lakes including Lake Gerald and Lake Roland, was historically categorized as oligotrophic but is now mesotrophic having experienced cultural eutrophication. A mass balance phosphorus budget model was constructed for the Twin Lakes system in Houghton, Co. Michigan for the 2022 stratified season. Additional spatial insights were gleaned through a survey of shoreline water quality, which corroborated the model results. The lakes currently experience substantial depletion of hypolimnetic dissolved oxygen during late summer stratification. A budget reveals approximately 22% (6.6 kg) of the current 29.5 kg total phosphorus inputs to Twin Lakes (during the …
Spatial Heterogeneity Of Nitrogen Cycling Within And Across Freshwater Ecosystems, Erin K. Eberhard
Spatial Heterogeneity Of Nitrogen Cycling Within And Across Freshwater Ecosystems, Erin K. Eberhard
Dissertations, Master's Theses and Master's Reports
Dinitrogen (N2) fixation and denitrification are two nitrogen (N) cycling processes that despite differences in environmental requirements and constraints, co-occur in aquatic ecosystems. The overall goal of this dissertation was to evaluate how spatial heterogeneity of environmental variables 1) drive hot spots of N2 fixation, denitrification rates and gene abundances in streams, 2) facilitate co-occurrence of these processes across wetland – stream – lake interfaces, and 3) affect differences in microbial community composition in streams across U.S. ecoregions. We found hot spots of both processes within 7 stream reaches in Michigan and Idaho, but rates of N …
Metagenomic Identification And Classification Of The Mercury-Methylating Gene Hgca In Response To Water Table And Plant Functional Group Manipulations In Peat Soil, Madeline Peterson
Metagenomic Identification And Classification Of The Mercury-Methylating Gene Hgca In Response To Water Table And Plant Functional Group Manipulations In Peat Soil, Madeline Peterson
Dissertations, Master's Theses and Master's Reports
Methyl-mercury (MeHg) is a potent neurotoxin that threatens the health of humans and wildlife alike. Climate warming threatens to shift regional precipitation and climate regimes in peatland environments, which could destabilize northern peatlands and accelerate both Hg release from soil and MeHg production. Peatlands are among the leading hotspots for MeHg, yet little is known about the community composition or functional relationship of mercury-methylating microbes in response to varying environmental conditions. The recognized mercury-methylating genes responsible for this activity are the obligatory gene pair hgcA and hgcB. Metagenomic data from the full-factorial peatland mesocosm experiment PEATcosm was obtained to …
Denitrification And Nitrogen Fixation Commonly Co-Occur But Rates Vary Throughout The Year And In Different Environments, Kevin Nevorski
Denitrification And Nitrogen Fixation Commonly Co-Occur But Rates Vary Throughout The Year And In Different Environments, Kevin Nevorski
Dissertations, Master's Theses and Master's Reports
Denitrification and nitrogen fixation are nitrogen cycling processes that can occur simultaneously in streams but are rarely studied together. The overarching goal of this dissertation was to quantify temporal and spatial variation of these processes in streams across the USA, characterize the environmental drivers of that variation, and determine the role that denitrification plays in the carbon cycle. To characterize temporal variation in these processes, a 2-year study in the Pilgrim River in Michigan’s Upper Peninsula found no difference in rates among seasons but high day-to-day variation in rates of both processes (maximum daily change 4,390 μg N/m2/hr …
Controls On Autotrophic Respiration, Heterotrophic Respiration, And Decomposition In Northern Forested Rivers, Renn Schipper
Controls On Autotrophic Respiration, Heterotrophic Respiration, And Decomposition In Northern Forested Rivers, Renn Schipper
Dissertations, Master's Theses and Master's Reports
Autotrophic respiration (AR), heterotrophic respiration (HR), and decomposition are important contributors to the carbon cycle in streams. It is important to understand how different environmental factors, such as canopy cover and dissolved organic carbon (DOC), influence these processes. DOC concentrations in northern forested streams are increasing, which may affect light and carbon availability. To examine the effects of DOC and canopy cover on these processes we measured gross primary production, ecosystem respiration and decomposition at 8 sites in 4 streams in the Upper Peninsula of Michigan and used quantile regression to estimate AR and HR. Among sites, AR and decomposition …
Regional Impacts Of Invasive Species And Climate Change On Black Ash Wetlands, Joseph Shannon
Regional Impacts Of Invasive Species And Climate Change On Black Ash Wetlands, Joseph Shannon
Dissertations, Master's Theses and Master's Reports
For more than a decade intensive research on the ecohydrology of black ash wetland ecosystems has been performed to understand these systems before they are drastically altered by the invasive species, emerald ash borer (EAB). In that time there has been little research aimed at the scale and persistence of the alterations. Three distinct but related research articles will be presented to demonstrate a method for moderate resolution mapping of black ash across its entire range, understand the relative impacts of EAB and climate change on probable future wetland conditions, and develop an experimental and modeling approach to quantify and …
The Effect Of Seasonality On Yellow Perch Ecology And Ecotoxicology Within Lake Manganese, Bailey Duxbury
The Effect Of Seasonality On Yellow Perch Ecology And Ecotoxicology Within Lake Manganese, Bailey Duxbury
Dissertations, Master's Theses and Master's Reports
Seasonality is a consistent component of aquatic ecosystems yet most fish biological and ecotoxicological studies commonly employ field sampling protocols focused during the warm open water season with minimal emphasis placed on winter sampling, especially for north-temperate latitude ecosystems. Such strategies limit our understanding of poikilotherm biology and ecology during the overwintering seasons. Here, I investigated seasonal changes in yellow perch (Perca flavescens) biology, ecology and ecotoxicology over a one-year period in Lake Manganese. Significant seasonality was observed for metrics including fish energy densities (kJ/g), gonadosomatic indices, whole-body lipid contents, and carbon stable isotope values (δ13C). …
Monitoring Mammal Community Shifts Across Silvicultural Treatments Utilizing Camera Traps And The Development Of Invertebrate- Derived Dna In Hardwood Forests Of North America, Shallen Gurtler
Dissertations, Master's Theses and Master's Reports
Mammal distribution and diversity is quickly changing as humans modify the landscape. In particular, silviculture, which is the practice of controlling the growth, structure, and quality of forests to meet the needs of society and the landowner, influences the habitat usage of mammals. Utilizing camera traps, I monitored shifts in mammal communities across different silviculture treatments in the northern hardwood forests of the Great Lakes region in North America. I assessed the community composition across six canopy treatments and three understory treatments with a total of 2,018 active camera trap nights with 3,321 detections over the course of 147 days. …
Plant Community Response To Novel Silvicultural Treatments In Great Lakes Northern Hardwoods, Stefan F. Hupperts
Plant Community Response To Novel Silvicultural Treatments In Great Lakes Northern Hardwoods, Stefan F. Hupperts
Dissertations, Master's Theses and Master's Reports
The objective of this dissertation is to assess plant community response across a range of silvicultural disturbances and test ecological hypotheses to better inform ecologists and forest managers. To provide context for the utility of revising silvicultural systems, I review natural disturbance regimes and historical practices that have shaped contemporary Great Lakes northern hardwood forests (Chapter 2). Further, I identify important ways to expand the silvicultural toolbox and better emulate natural disturbance regimes. Building on this theoretical underpinning, I investigate the initial regeneration and plant community response to two novel silvicultural experiments: the Northern Hardwood Experiment for Enhancing Diversity (NHSEED) …
Effects Of Invasive Watermilfoil And Seasonal Dynamics On Primary Production In Littoral Zones Of North-Temperate Lakes, Ryan R. Van Goethem
Effects Of Invasive Watermilfoil And Seasonal Dynamics On Primary Production In Littoral Zones Of North-Temperate Lakes, Ryan R. Van Goethem
Dissertations, Master's Theses and Master's Reports
Climate change and species invasion are two agents of global change altering aquatic ecosystems worldwide. Submerged aquatic macrophytes control lake ecosystem processes through their direct and indirect interactions with other primary producers, but how their interactions may be altered by species invasions or how they function over full seasonal cycles in temperate lakes is poorly understood. We first addressed whether the presence of invasive watermilfoil (IWM) altered standing crops and gross primary pro-duction (GPP) of other littoral primary producers (macrophytes, phytoplankton, attached algae or periphyton) in littoral zones of 6 Michigan lakes. We found no differences in primary producer standing …
Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp
Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp
Dissertations, Master's Theses and Master's Reports
Boreal peatlands store approximately one third of the earth’s terrestrial carbon, locked away in currently waterlogged and frozen conditions. Peatlands of boreal and arctic ecosystems are affected increasingly by shifting hydrology caused by climate change. The consequences of these relatively rapid ecosystem changes on carbon cycling between the landscape and the atmosphere could provide an amplifying feedback to climate warming. Alternatively, the advancement of terrestrial vegetation into once waterlogged soils could uptake carbon as a sink. Previous work suggests that fens will become an increasingly dominant landscape feature in the boreal. However, studies investigating fens, their response to hydrologic and …
Microbial Community Response To Light And Heavy Crude Oil In Freshwater Systems, Timothy M. Butler
Microbial Community Response To Light And Heavy Crude Oil In Freshwater Systems, Timothy M. Butler
Dissertations, Master's Theses and Master's Reports
With increased demand for oil, there is an increased risk for oil spills in many environments. A number of pipelines transport oil near or across freshwater systems including the Great Lakes. Microbes are capable of breaking down oil and have thus been proposed as tools for oil spill response through bioremediation. There is a need to understand the microbial response to diverse oil types in freshwater environments due to the lack of research into this topic. This study’s main objectives are to understand how the freshwater microbial communities respond to oil, and how the bacterial communities may respond to different …
Ecological Implications Of Foraging And Life-History In Three Cold-Adapted Species, Andrew Von Duyke
Ecological Implications Of Foraging And Life-History In Three Cold-Adapted Species, Andrew Von Duyke
Dissertations, Master's Theses and Master's Reports
This research investigates the ecology of: ringed seals (Pusa hispida), moose (Alces alces), and bowhead whales (Balaena mysticetus). Each of these species draws upon specialized strategies to meet the physical demands of life in their extreme environments. However, they are currently experiencing unprecedented changes in their habitats. This work adds to what is known about the behavior, physiology, and population dynamics of cold-adapted species—providing insights of value for an improved understanding of foraging and life-history theory, and informing conservation and ecosystem monitoring efforts. Chapter 1 provides a brief introduction to the scope of work …
Assessment Of Arctic Grayling Re-Introduction Potential In The Big Manistee River, Michigan., Cameron Goble
Assessment Of Arctic Grayling Re-Introduction Potential In The Big Manistee River, Michigan., Cameron Goble
Dissertations, Master's Theses and Master's Reports
Arctic Grayling Thymallus arcticus were once the dominant fluvial salmonid species in Michigan’s Lower Peninsula. By the late 19th century most populations in the State had experienced drastic declines and by 1936 the species was declared extinct in Michigan. Beginning in 2011 the Little River Band of Ottawa Indians and Michigan Technological University partnered on research to determine the feasibility of re-establishing the species in the Big Manistee River watershed which was home to one of the last Arctic Grayling populations in the Lower Peninsula. The objectives of this research were to: A) assess abiotic habitat suitability for Arctic …
Characterization Of Ecological Water Stress In The U.S. Great Lakes Region Using A Geospatial Modeling Approach, Sara Alian
Dissertations, Master's Theses and Master's Reports
Anthropocentric water resources management affects aquatic habitats by changing streamflow regime. Understanding the impacts of water withdrawal from different sources and consumption by various economic sectors at different spatial and temporal scales is key to characterizing ecologically harmful streamflow disturbances. To this end, we developed a generic, integrative framework to characterize catchment scale water stress at annual and monthly time scales. The framework accounts for spatially cumulative consumptive and non-consumptive use impacts and associated changes in flow due to depletion and return flow along the stream network. Application of the framework to the U.S. Great Lakes Region indicates that a …
The Spatial Ecology Of Gray Wolves In The Upper Peninsula Of Michigan, 1994–2013, Shawn O'Neil
The Spatial Ecology Of Gray Wolves In The Upper Peninsula Of Michigan, 1994–2013, Shawn O'Neil
Dissertations, Master's Theses and Master's Reports
All natural processes are dynamic in space and time. Establishing the links between spatiotemporal patterns and ecological processes is critical for improving our understanding of natural systems. Empirical data representing wildlife populations is accumulating and increasingly involves spatiotemporal components. Wildlife monitoring programs for threatened, endangered, or other species of interest often involve radio-tracking of a sample of individual animals combined with census data. Such data are valuable both for conservation and management of populations and for testing ecological theories about species distribution and what influences patterns over time. We used 20 years of radio telemetry and snow tracking data to …
Impacts To Biodiversity And Ecosystem Services From Bioenergy Development: A Pan American Experience, Colin Phifer
Impacts To Biodiversity And Ecosystem Services From Bioenergy Development: A Pan American Experience, Colin Phifer
Dissertations, Master's Theses and Master's Reports
As part of a broader project that evaluated the social and ecological sustainability of bioenergy, I studied the effects of bioenergy associated land-use change and management on native bees and birds in two bioenergy-producing countries, the United States and Argentina. In Argentina, I worked in Entre Ríos province where eucalyptus (Eucalyptus spp.) plantations are being planted. These fast-growing trees are replacing pasture and annual crops, the current dominant land use. I surveyed for native bees and birds in pastures/annual crops and large-scale eucalyptus plantations, as well as mixed-use farms and native espinal savannas. Both birds and bees declined in …
Carbon Flux Dynamics In High Altitude Peatlands In The Ecuadorian Andes, Maria Elisa Sanchez Garces
Carbon Flux Dynamics In High Altitude Peatlands In The Ecuadorian Andes, Maria Elisa Sanchez Garces
Dissertations, Master's Theses and Master's Reports
Although knowledge of peatland CH4 and CO2 exchange in temperate mountain ecosystems is available, information about carbon (C) exchange in peatlands of the Andean mountains is limited and these ecosystems may behave differently given the particular characteristics of the Andean tropics. These ecosystems are highly productive and under pressure by grazing. Our first objective was to measure baseline carbon dioxide (CO2) and methane (CH4) flux in an undisturbed peatland in Cayambe-Coca National Park. Our second objective was to quantify CO2 and CH4 fluxes in an intensively cattle grazed peatland near Antisana Ecological …
Assessing The Impacts Of Climate Change On The Surface Temperature Of Inland Lakes In Michigan, Kaitlin Reinl
Assessing The Impacts Of Climate Change On The Surface Temperature Of Inland Lakes In Michigan, Kaitlin Reinl
Dissertations, Master's Theses and Master's Reports
The aim of this study was to validate and apply a lake model for predicting the susceptibility of small inland lakes in Michigan to changes in thermal regime and increased cyanobacteria growth as a result of future climate conditions. The Freshwater Lake Model was selected, tested for sensitivity to various inputs, and validated through comparison to observed conditions. The sensitivity analysis showed that the lake model was most sensitive to solar radiation, air temperature, and air humidity. Comparison of predicted climate data with observed conditions revealed highly variable climate model error. The lake model validation was conducted using 10 lakes …
Vegetation Dynamics And Nitrogen Cycling Responses To Simulated Emerald Ash Borer Infestation In Fraxinus Nigra-Dominated Wetlands Of Upper Michigan, Usa, Joshua Davis
Dissertations, Master's Theses and Master's Reports
Throughout many North American forests, the invasive emerald ash borer (EAB, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)) is a significant threat to biodiversity and ecosystem processes. The fate of Fraxinus nigra Marshall (black ash) is of particular concern, as it is frequently a dominant canopy species across much of its range. A multiyear manipulative study was conducted to investigate the potential impacts of EAB on vegetation dynamics and nitrogen (N) cycling in nine F. nigra-dominated wetlands of Upper Michigan, USA. The effects of early- and late-stage infestations were simulated by girdling (‘Girdle’) or felling (‘Ash-Cut’) all ash stems greater than …