Digital Commons Network^™

Examining Dissolved Gases In A Changing Climate, Allison Staniec

Doctoral Dissertations

Changing climate scenarios predict a variety of effects across land, ocean, and atmosphere. In this dissertation the effect of several climate change related phenomena on dissolved gases in the coastal ocean and across the ocean-atmosphere interface is examined. Warming temperature, as predicted by the IPCC (2014), has direct impacts on the capacity of water to act as a reservoir for dissolved gases through its effect on their solubility (Chang, 2010). The first portion of this dissertation addresses dissolved gases in a coastal estuary, where warming is expected to be accelerated relative to the open ocean. A representative gas, oxygen, is …

Fine-Scale Climates And Evolution Alter Species Responses To Climate Change, Christopher Nadeau

Doctoral Dissertations

Predictions suggest that climate change could cause the extinction of up to a million species. However, scientists debate the accuracy of these predictions. In this dissertation, I explore whether often-ignored aspects of climate and biology alter predictions of climate change impacts. In Chapter 1, I show that studies predicting extinction risk under climate change ignore important aspects of climate by using climate data with coarse spatial and temporal resolutions. In Chapter 2, I propose that the degree to which climates vary over space and time in a region can predict the vulnerability of species to climate change. I suggest that …

Evaluating Climate Change Impacts On Drinking Water Reservoirs And Wastewater System Resilience In Connecticut, U.S.A., Cristina Mullin

Doctoral Dissertations

Societies depend on the proper functioning and resilience of critical infrastructure systems including those for drinking water and wastewater, but these systems are vulnerable to natural and anthropogenic stressors. For example, wastewater systems are especially susceptible to extreme weather events while drinking water systems are vulnerable to diminished source water quality — both of which can disrupt proper functioning. Climate change and human development, economic problems, and pollution further challenge water system resilience. Despite the criticality of these systems and known vulnerabilities, little scholarship exists that aims to interrogate their resilience. This dissertation attempts to narrow this gap in the …

Predicting Pelargonium Responses To Climate Change In A Biodiversity Hotspot Throughout South Africa, Tanisha Marie Williams

Doctoral Dissertations

Climate change is causing major shifts in species distributions, which fundamentally alters the species composition and functioning of biological communities across the globe. Projections suggest that by 2100 up to one of every six species will become extinct. Such drastic changes will have significant impacts on biodiversity patterns and ecosystem functioning. Ecologists are faced with the pressing work of trying to understand how plants will respond to changing and increasingly stressful environments. To predict the long-term effects and magnitude of species responses, it is imperative that species adaptive responses are understood across the entirety of their geographic ranges. My dissertation …

Vulnerability Of Small Island Developing States Across Multiple Scales, Neil Oculi

Doctoral Dissertations

Abstract: Small Island Developing States (SIDS) are among the countries most vulnerable to climate change because of their isolation, geopolitical stature, and limited resources. Climate change will continue to exacerbate SIDS’ vulnerabilities. With this in mind, in this dissertation, I will investigate implications of vulnerabilities of SIDS at global, regional, and local scales.

The first chapter examines the discourse on vulnerability to climate change and its many complexities. Among these is the constant tension between policy makers and academics about vulnerability. This chapter unpacks these complexities in order to analyze how SIDS deal with the notion of vulnerability at the …

Birds And Berries: Projecting The Responses Of Seed Dispersal Networks To Climate Change, Manette E. Sandor

Doctoral Dissertations

Climate change has caused species range shifts, with more predicted in coming decades. Range shifts could result in secondary threats such as spatial mismatch with mutualist partners and movement out of protected areas. We found that due to range shifts, shrub species richness will be lost at higher elevations, and species turnover will peak at middle elevations. Areas of bird species turnover will only partially overlap with areas of shrub species turnover, which could result in broken interactions between partners. Our projections suggest that climate change will result in clear winners and losers with some species gaining and others losing …

Land-Atmosphere Interactions And Regional Climate In West Africa And South America, Amir Erfanian Javadian Entezar Yazd

Doctoral Dissertations

Land, atmosphere, and oceans interact with each other through energy, mass, and momentum exchanges. These interactions regulate climate variability and influence climate changes at the regional scale. One notable example of highly influential land-atmosphere-ocean interactions on regional climates is monsoonal systems that influence a substantial portion of the world’s population. In this dissertation, the present and future climates of West Africa (WA) and South America (SA), two important monsoon regions, were studied utilizing Regional and Global Climate Models (RCMs and GCMs), mathematical techniques and data mining tools, and observational data (in-situ, remote-sensing, and reanalysis). The objective is to advance our …

The Extinction Of The Carolina Parakeet And Multiple Dimensions Of Global Parrot Biodiversity, Kevin R. Burgio

Doctoral Dissertations

The study of the ecology of a species has traditionally ceased when that species goes extinct, despite the benefit to current and future generations of potential findings. We used the Carolina parakeet to develop a framework investigating the distributional limits, migratory habits, and extinction process as a means to recover important information. We developed a comprehensive database of every known occurrence of this iconic species. Using a combination of environmental niche modeling and extinction estimating analyses, our results demonstrate that the Carolina parakeet’s range was smaller than previously believed, the eastern and western subspecies occupied different niches with broad geographic …

Climate-Induced Habitat Fragmentation Affects Metapopulation Structure Of Arctic Grayling In Tundra Streams, Heidi E. Golden

Doctoral Dissertations

Climate change is altering ecosystems across the globe, with ecological and evolutionary consequences affecting species persistence and biodiversity. I investigated the effects of changing hydrology on Arctic grayling (Thymallus arcticus) metapopulation structure, microgeographic differentiation, movement patterns and vital rates using neutral genetic microsatellite markers, remote sensing of PIT-tagged individuals, body condition and ovarian histology. Arctic grayling within the study area on Alaska’s North Slope comprised five distinct genetic clusters. River distance and dry zones were significant factors explaining genetic differentiation among locations. Migration was low and asymmetrical among genetic clusters, but higher from headwater populations to the large …

A Threatened Ecosystem In A Human-Dominated Landscape: Tidal Marsh Conservation In The Face Of Sea-Level Rise, Christopher R. Field

Doctoral Dissertations

Biological conservation is a crisis-driven discipline that is inextricably linked to its broader social, political, and economic context. Historically, conservation research has often been conducted within ecology disciplines and with limited links to this broader context, which has contributed to a gap between research and its real-world implementation. One impediment to creating stronger interdisciplinary links is that it requires the integration of many types of data from across a range of disciplines. Owing to the difficulty of such integration, questions related to the relative importance of different types of knowledge in conservation decision-making have remained largely unexplored. I collected data …

Understanding The Hydrological Impacts Of Climate Variability And Climate Change Based On Numerical Modeling And Observations, Dana Thomas Parr

Doctoral Dissertations

The objective of this dissertation research is to better understand the hydrological impacts of climate variability and climate change. This objective is first addressed in a two-part study focusing on the Northeast US using the Connecticut River Basin as a case study. Changes to the hydrological cycle are investigated for the past several decades using precipitation and river discharge data from observations and soil moisture and evapotranspiration (ET) from the VIC hydrological model. From 1950-2011 a clear increase of precipitation intensity is identified, together with increasing precipitation amount, discharge, runoff ratios, and soil moisture. The ET trend is negligible. This …

Observed And Simulated Processes Linked To The Recent Climate Variability And Changes Over The Greater Horn Of Africa, Vincent O. Otieno

Doctoral Dissertations

The main objective of this dissertation is to document characteristics of the processes and mechanisms associated with 20^th and 21^st century spatio-temporal modes of climate variability and changes over the Greater Horn of Africa (GHA) region.

This thesis research comprises three major parts. The first part used output from ten Earth System Models (ESMs) from the fifth phase of coupled model intercomparison project to characterize seasonal and annual mean precipitation cycle over the Greater Horn of Africa (GHA) region. Each ESM had at least 2 ensemble members. In spite of distributional anomalies of observations, ESM ensemble means were …