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Full-Text Articles in Life Sciences

Under Ice Photosynthetic Primary Production And Dark Carbon Fixation In A Temperate Freshwater System, Vanessa Cubillos Tellez Jan 2023

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 …


Tropical Plant Physiological Responses To Experimental Warming And Hurricane Disturbance, Robert Tunison Jan 2023

Tropical Plant Physiological Responses To Experimental Warming And Hurricane Disturbance, Robert Tunison

Dissertations, Master's Theses and Master's Reports

Tropical forests exchange more carbon with the atmosphere than any other biome, but their responses to climate change are largely understudied. The work presented in this dissertation uses a tropical understory warming experiment that was hit by a hurricane disturbance to investigate how plant physiology responds to multiple types of climate change pressures. We measured the potential for root respiration, leaf photosynthesis & respiration, and leaf thermotolerance acclimation to experimental warming while recovering from hurricane disturbance. We found there was thermal acclimation via decreased ecosystem root respiration, increased photosynthetic thermal niche breadth, and decreased quantum efficiency for some species at …


Characterization Of Vernal Pools Across National Parks In The Great Lakes Region, Samantha R. Kurkowski Jan 2023

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 Jan 2023

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 …


White-Tailed Deer In A Winter-Wonderland: Long-Term Deer Yard Use And Methodological Considerations For Ungulate Fecal Dna Metabarcoding, Melanie A. Ottino Jan 2023

White-Tailed Deer In A Winter-Wonderland: Long-Term Deer Yard Use And Methodological Considerations For Ungulate Fecal Dna Metabarcoding, Melanie A. Ottino

Dissertations, Master's Theses and Master's Reports

Northern white-tailed deer (Odocoileus virginianus) mitigate the increased energetic costs of severe winter conditions through obligate migration to densely congregated areas with abundant conifer cover, a behavior referred to as yarding. “Deer yards” in the Western Upper Peninsula (UP) of Michigan are principally located within the reduced snowpack and increased ambient temperature microclimates of densely canopied eastern hemlock (Tsuga canadensis) stands, but specific drivers of long-term site fidelity and utilization are largely uncharacterized. As an important game species of high economic and cultural value and a keystone herbivore with critical impact of plant community composition and structure, identifying winter yarding …