Life Sciences Commons^™

Effects Of Temperature On Growth And Molting In Blue Crabs (Callinectes Sapidus) And Lesser Blue Crabs (Callinectes Similis), Abigail Ann Kuhn

Master's Theses

Temperature can exert impacts on many processes in ectotherms. With global temperatures rising due to climate change, many ectothermic species may exhibit changes in growth rates and size at maturity, and these changes can have population-level effects. Predicting responses of species to climate change will require not only knowledge of thermal tolerance limits, but also effects of temperature change on growth rates and other life history parameters. For arthropods that exhibit discontinuous growth (i.e., molting), this includes both intermolt period and growth per molt. Previous laboratory and field experiments suggest that temperature affects both intermolt period (IMP) and growth per …

Combined Effects Of Dissolved Oxygen And Temperature On Aerobic Respiration And Respiratory Recovery Responses Of The Spioniform Polychaete, Streblospio Gynobranchiata, In Relation To Body Size, Alyssa Bennett

Master's Theses

Elevated surface temperatures exacerbate the threat of hypoxia within coastal ecosystems. These two primary stressors likely interact as they elicit opposing physiological responses from marine organisms. Metabolic depression is typically associated with hypoxia, while metabolic rates increase with temperature. Moreover, physiological effects of combined stressors may not be additive. In light of increasing pressures from hypoxia, elevated ocean temperatures, and other stressors within coastal regions, studies need to examine effects of multiple stressors on physiology of coastal organisms.

Mass-specific aerobic respiration (V_O2) was characterized as a proxy for metabolic cost of Streblospio gynobranchiata, at combined levels of …

Understanding Community And Ecophysiology Of Plant Species On The Colorado Plateau, Hannah Elizabeth Yokum

Theses and Dissertations

The intensification of aridity due to anthropogenic climate change is likely to have a large impact on the growth and survival of plant species in the southwestern U.S. where species are already vulnerable to high temperatures and limited precipitation. Global climate change impacts plants through a rising temperature effect, CO2 effect, and land management. In order to forecast the impacts of global climate change, it is necessary to know the current conditions and create a baseline for future comparisons and to understand the factors and players that will affect what happens in the future. The objective of Chapter 1 is …

Understanding Community And Ecophysiology Of Plant Species On The Colorado Plateau, Hannah Elizabeth Yokum

Theses and Dissertations

The intensification of aridity due to anthropogenic climate change is likely to have a large impact on the growth and survival of plant species in the southwestern U.S. where species are already vulnerable to high temperatures and limited precipitation. Global climate change impacts plants through a rising temperature effect, CO2 effect, and land management. In order to forecast the impacts of global climate change, it is necessary to know the current conditions and create a baseline for future comparisons and to understand the factors and players that will affect what happens in the future. The objective of Chapter 1 is …

Estimating The Range Shift And Harvesting Intensity Of Junipers In Bhutan (Eastern Himalaya), Rinchen Namgay

Theses

The authors of more than 97% of the scientific publications on climate change agree that global temperature has increased in the last six decades and is caused by human beings via emission of greenhouse gases in the atmosphere. This phenomenon has altered natural ecosystem functions, causing many species to shift to a more suitable habitat. Throughout the world, because of recent climate warming, many forms of range shift associated with climate warming has occurred. While animals can move as warming happens, plants being stationary organisms cannot move, so the difference in the distribution of different plant life stages is an …

Elevated Temperature And Co2 Concentrations Affect Carbon Flux In Two Boreal Conifers, Sasha Madhavji

Electronic Thesis and Dissertation Repository

Elevated temperatures and CO₂ will alter carbon flux in two dominant boreal tree species Picea mariana (black spruce) and Larix laricina (tamarack). Trees were grown in three temperature treatments (ambient, ambient +4 °C, and ambient +8 °C) at either 400 ppm or 750 ppm CO₂, to simulate climate conditions between now and the year 2100. Spruce acclimated to increasing temperature detractively; warming scenarios reduced spruce net carbon gain. Tamarack maintained comparable levels of net photosynthesis (A_net) across warming treatments and both species acclimated respiration (R_dark) with increasing growth temperature. Elevated CO₂-grown …

Long-Term Changes In A Spatially Subsidized Insular Ecosystem In The Archipelago Of Bahía De Los Ángeles, Baja California, Mexico, Thais Fournier

Theses

Interactions between climate change and the processes that structure coastal communities are poorly understood.Long – term weather patterns that include extreme events (e.g., El Niño Southern Oscillation, or “ENSO”) allow us to test hypotheses of how changes in weather (e.g., precipitation) will influence communities over long time frames. One system that is particularly vulnerable to climate changes is the coastal ecotone, which occupies 8% of the earth’s surface. A large exchange of resources (spatial subsidies) link habitats across this ocean – land interface, often with dramatic consequences for the recipient systems. Spatial subsidies such as marine input influence …

Rethinking Urban Green Infrastructure As A Means To Promote Avian Conservation, Allen Lau

Master's Projects and Capstones

There is an under-recognized potential for cities to use urban green infrastructure to contribute to avian biodiversity conservation. At the global scale, climate change and growing urbanization are primary global drivers leading to decline and homogenization in world bird populations. Birds are fundamental and intricate species in ecosystems, and even in urban areas, act as indicator and regulator species contributing to healthy ecosystem function. While many cities have recognized the economic and social benefits associated with green spaces, such as the vast benefits ecosystem services provide to the urban dweller, the use of green spaces to concurrently contribute to avian …

The Effects Of Anthropogenic Stress On Nitrogen-Cycling Microbial Communities In Temperate And Tropical Soils, George S. Hamaoui Jr.

Doctoral Dissertations

In this dissertation several research studies are discussed that characterize the effects of anthropogenic, or human-induced, stress on both ammonia-oxidizing and total bacterial soil microbial communities. The disturbances of land-use change in tropical, South American rainforests and artificial warming and nitrogen (N) fertilization in temperate, North American forests were investigated as these disturbances represent past and current disturbances caused by human landscape alteration and climate change. Initially, the response of soil ammonia-oxidizing microbial communities to land-use change from primary rainforest to pasture and, finally, back to secondary forest was determined. Next, these analyses of land-use change effects were expanded to …

Spatial And Temporal Variation In Mangrove Distribution (1950-2014) In Tampa, Florida Usa, Carolyn Cheatham Rhodes

USF Tampa Graduate Theses and Dissertations

I carried out an observational study of historic high resolution aerial imagery spanning six decades (1950-2014) to identify recent and historic spatial extent of mangrove forests, within the municipal boundaries of the City of Tampa, Florida USA. My objectives were to map mangrove distribution and spatial extent and any change or patterns of change discernable. I observed variable patterns of change and rates of expansion varied between sites spatially as well as within sites between time intervals. I found notable changes in mangrove extent in the Tampa from historic and modern aerial imagery for the ~64-year period between 1950 and …

Understanding The Complex Relationships Between Climate, Vegetation, And Foraging Behavior Of A Climate-Sensitive Alpine Mammal In Order To Explain Patterns Of Persistence, Evan Cole

Master's Projects and Capstones

Mountain ecosystems offer substantial ecosystem services but are highly sensitive to climate change. The American pika (Ochotona princeps) serves as an indicator species of climate change and a model organism for studying its impacts on mountain mammals. Certain aspects of plant community composition and structure can function as predictors of pika distribution, but understanding the links between climate, forage quality, and foraging behavior is necessary to identify the mediating mechanism. Pika foraging pressure help shape the local plant community, which can confound modeling efforts and must be considered when evaluating the influence of vegetation on pika persistence. Plant …

Using Maximum Entropy Species Distribution Modeling For Long-Term Conservation Planning Of Three Federally Listed Bats In North America, Mitchell L. Meyer

Master's Theses

We are currently in a sixth mass extinction event in which the extinction rate is higher than it has ever been. This mass extinction event is caused by human influence on the environment. Biodiversity is worth conserving because of its many uses to humans. Bats are a diverse group of mammals that humans rely on for pest control services. The gray bat, northern long-eared bat, and Indiana bat are on the Threatened and Endangered Species List and are in need of conservation. I built species distribution models using occurrence records, climate data, and Maximum entropy (MaxEnt) modeling technique. I predicted …

Financial Assessment Of Agricultural Lands At Risk To Coastal Salt Marsh Migration In Relation To Climate Change Induced Sea Level Rise In Dorchester County, Maryland, Jewell Porter

International Development, Community and Environment (IDCE)

The increasing rate and effects of sea level rise is a major environmental concern in the Chesapeake Bay. This paper evaluates the impacts of rising sea level on coastal salt marshes and the surrounding agricultural lands at risk in Dorchester County, Maryland to build off existing environmental monitoring work performed by NOAA’s Sentinel Site Program. The results of the spatial analysis were used to estimate monetary benefits to incentivize farmers to protect these marshes by making their land available for marsh migration to occur. Looking at three scenarios of sea level rise and marsh migration, grain crops (corn, soybeans, and …

Direct And Indirect Effects Of Climate Change On Plant Populations And Communities In Sagebrush Steppe, Andrew R. Kleinhesselink

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rapid climate change presents humanity with a number of big problems. Foremost among these is the sad fact that the climate we will pass on to our children will likely be nothing like the climate that we inherited from our parents. Ecologists have collected solid evidence that climate change has already begun to affect the living things around us and the ecosystems humans depend on. Unfortunately, predicting the future effects of climate change on life on earth is not easy. We focused on three research goals as part of an effort to improve our ability to predict how plants and …

Plasticity And Biotic Interactions Mediate Plant Persistence In A Changing World, Alix Ann Pfennigwerth

Masters Theses

Anthropogenic global change is occurring today at a faster rate and larger scale than ever before. Understanding how plants will respond to such large-scale disturbance is critical for biodiversity conservation, yet the ecological and evolutionary mechanisms underlying these responses remain poorly understood. In this thesis, I investigated the mechanisms underlying plant response to two major drivers of global change, climate change and the widespread mortality of foundation species. First, I examined genetic and plastic plant trait responses to climatic variation using elevation gradients, which serve as space-for-time substitutions for climate change. Through field observations in three populations of the North …

Growth Of Orbicella Faveolata In La Parguera, Puerto Rico, Darren B. Marshall

HCNSO Student Theses and Dissertations

Reef-building corals are subject to high amounts of stress, including pollution and rising sea surface temperatures due to climate change. These factors can affect the ability of corals to produce their calcium carbonate skeletons. Evaluation of the effects of climate change may be facilitated by evaluation of records of coral skeletal growth over a long period of time. The aim of this study was to evaluate skeletal growth of the coral Orbicella faveolata in La Parguera, Puerto Rico over a 32-year period. For this, 14 Orbicella faveolata core samples were collected from corals at two reefs (1.2 km apart) in …

Methods For Incorporating Ecological Impacts With Climate Uncertainty To Support Robust Flood Management Decision-Making, Caitlin M. Spence

Doctoral Dissertations

Modern and historic flood risk management involves accommodating multiple sources of sources of uncertainty and potential impacts across a broad range of interrelated sectors. Sources of uncertainty that affect planning include internal climate variability, anthropogenic changes such as land use and system performance expectations, and more recently changes in climatology that affect the resources supporting the system. Flood management systems potentially impact human settlements within and beyond the systems’ scope of planning, local weather patterns, and associated ecological systems. Federal guidelines across nations have called for greater consideration of uncertainty and impacts of water resources planning projects, but methods for …

Role Of Community Social Capital For Acute Food Security Following An Extreme Weather Event, Alana N. Chriest

Graduate College Dissertations and Theses

Worsening climate changes effects are predicted to increase the severity and frequency of extreme weather events (EWE), which can disrupt food systems, from the local to global level, and compromise community food security. In the rural U.S., food insecurity, poverty, low economic growth, and population loss are prevalent, and rural communities often lack the physical capital to bolster community resiliency to climate change adaptation. In 2011, Tropical Storm Irene (TS Irene) in Vermont was the most damaging EWE the state’s history. Severely damaged roads, infrastructure, homes, and land, rendered many rural towns isolated for up to several days. The levels …

Quantifying Tree Response To Alterations In Pollution Deposition And Climate Change In The Northeastern Us, Alexandra M. Kosiba

Graduate College Dissertations and Theses

Understanding tree physiological responses to climate change is critical for quantifying forest carbon, predicting species' range change, and forecasting growth trajectories. Continued increases in temperature could push trees into conditions to which they are ill adapted -- such as decreased depth of winter snow cover, altered water regimes, and a lengthened effective growing season. A complicating factor is that in the northeastern United States, climate change is occurring on a backdrop of acid deposition and land-use change. In this dissertation, I used three studies to investigate the spatiotemporal nuances of resultant tree and sapling physiology to environmental change.

First, I …

A Comparison Of Benthic Macroinvertebrate Assemblages Between Perennial And Intermittent Headwater Streams Of The Mattole River In Northern California, Usa, Mason S. London

Cal Poly Humboldt theses and projects

Intermittent streams are common throughout the world and comprise 60% or more of total river lengths in the conterminous United States. Despite their prevalence, intermittent streams are understudied, particularly first-order headwater streams, which are vital for maintaining the function, health and biotic diversity of river networks. In June 2016, I sampled five intermittent and five perennial headwater streams in the Mattole River watershed in northwestern coastal California, USA, to compare benthic macroinvertebrate (BMI) assemblages between intermittent and perennial streams. BMI samples were collected using a 500µm mesh D-net at eight randomly located riffles along a 150-m reach, and then composited, …

Exploring Historical Coffee And Climate Relations In Southern Guatemala: An Integration Of Tree Ring Analysis And Remote Sensing Data, Diego Pons

Electronic Theses and Dissertations

This dissertation makes use of a physical geography perspective to examine the relationship between agriculture and climate in Guatemala using dendrochronology. I examined the potential of high-resolution climate proxy data from dendrochronology to help fill in the gaps of past climate information to better understand the natural and anthropogenic variability of precipitation which, in turn, can inform Guatemala’s agriculture sector. This research has demonstrated successful cross-dating and climate sensitivity of Abies guatemalensis in the Pacific slope of Guatemala. Based on this, I have produced a 124-year record of mean precipitation from June-July-August. The mean precipitation from June-July-August at this site …

Political Ecology Of Medicinal Plant Use In Rural Nepal: Globalization, Environmental Degradation, And Cultural Transformation, Emily Dovydaitis

Honors Undergraduate Theses

Prior to the advent of biomedicine, rural communities in Nepal relied on phytochemically active compounds in medicinal plants as their primary source of medicine; however, ethnobotanical practices have shifted over time due to economic, environmental, and sociocultural stimuli. Findings from 2016 fieldwork conducted in Dumrikharka, Nepal and Tutung, Nepal are compared to existing literature to describe the political ecology of medicinal plants in rural Nepal.

Anthropogenic climate change threatens individual plant species and ecosystem biodiversity. Globalized markets unabated by weak conservation programs place increasing demands on medicinal plants. As indigenous plants become overharvested and more difficult to access, Nepalis incorporate …

Effects Of In-Situ Leaf-Level Canopy Warming In A Northern Hardwood Forest, Kelsey Carter

Dissertations, Master's Theses and Master's Reports

Rising mean annual temperatures due to climate change have intensified the need to understand the effects of warming on plant physiological processes. Forest photosynthesis is the most important pathways of terrestrial carbon sequestration, yet continued warming could reduce this important carbon sink. Photosynthesis is highly sensitive to temperature and begins to decline after an optimum temperature (T_opt) is reached, leading to reduced carbon uptake. To date, logistical difficulties have limited our ability to test photosynthetic responses to sustained warming in mature forest canopies. In order to understand how elevated temperatures will affect forest ecosystems, we need to be …

Genotype × Environment × Management: Implications For Selection To Heat Stress Tolerance And Nitrogen Use Efficiency In Soft Red Winter Wheat, Kathleen Russell

Theses and Dissertations--Plant and Soil Sciences

The complex interaction of genetics, environment and management in determination of crop yields can interfere with selection progress in breeding programs. Specifically, the impact on selection for nitrogen use efficiency (NUE) in wheat (Triticum aestivum L.) under changing climatic conditions can be confounded by these interactions. Temperature increases for the southeastern United States are projected to range from 1-3°C by 2050 with nighttime temperatures increasing more rapidly than day temperatures. High temperatures are known to affect crop development and breeding for tolerance to heat stress is difficult to achieve in field environments. We utilized a multi-environment trial to assess …

Habitat Use By Wintering Passerines In Fire-Managed Forests Along The U.S. Gulf Coast, Justin Michael Michaud

Online Theses and Dissertations

Coastal habitats are being impacted by land development, fragmentation, and disturbance related to climate change. The remaining natural areas need to use planned management that may, in some cases, include the use of prescribed fire to maintain habitat quality. Numerous species of passerines, including some with declining populations, use the Gulf Coast as a wintering area, and some depend on habitats managed by fire. To provide information for land managers, I studied the winter bird community at Naval Live Oaks in Gulf Islands National Seashore with two primary objectives: (1) to describe the distribution, abundance, and diversity of the non-breeding …

Climate Change, Spruce Root Phenology, And Allocation Of Carbon Below- And Above-Ground, Marie Louise Orton

Legacy Theses & Dissertations (2009 - 2024)

Tree ring analysis has relied on a close relationship between climate and photosynthetically-derived stem enlargement. Lengthening growing seasons associated with climate warming have been predicted to enhance carbon sequestration as wood in trees, but this

Limited Evidence For Co2-Related Growth Enhancement In Northern Rocky Mountain Pinus Contorta Populations: Trends In Growth And Intrinsic Water-Use Efficiency Across Climate Gradients, Charlotte C. Reed

Graduate Student Theses, Dissertations, & Professional Papers

Forests sequester large amounts of carbon annually; however, the degree to which enhanced forest productivity is due to more conducive climate or CO₂ fertilization remains uncertain. Increasing atmospheric CO₂ may enhance photosynthesis and/or decrease stomatal conductance thereby enhancing intrinsic water use efficiency (iWUE). While increasing iWUE has been observed in most trees globally, this increase does not necessarily translate into greater growth. This study aims to evaluate whether responses of radial growth and iWUE to increasing CO₂ vary across climatic gradients. To investigate interactions between climate and CO₂ and their impacts on tree physiology and growth, …