<p> Animal movement influences ecological and biogeographical dynamics, and studying it reveals helpful insights at a time when anthropogenic activities have accelerated rates of climatic and land cover change. This dissertation addresses three fundamental questions in ecology and biogeography linked to the movement and distribution of animals. First, how do animal movements affect their environments? Second, how do the effects of land use change interact with atmospheric climate change to alter species distributions? Third, how do organisms track their climatic niches through time and space? Each question is addressed with a separate study, each generating methods and results with implications for future academic work, management, and conservation. </p><p> In the first study, I tracked the daily movements of the common hippopotamus, <i> Hippopotamus amphibius</i>, a megaherbivore that transports nutrient-rich biomass between terrestrial and aquatic ecosystems. I developed a spatially explicit biomass transfer model that relates rates of ingestion and egestion to movement behavior states derived from the movement data. The biomass transfer model revealed the process by which <i>H. amphibius</i> generates patterned landscapes of nutrient removal and deposition hotspots. In addition, the model generated maps of these nutrient transfer landscapes, making it possible to explore the spatial dynamics of nutrient transfers, and showing that the amount of biomass transferred reaches levels equivalent to rates of aboveground net primary productivity. In addition to revealing the influences of <i>H. amphibius</i> on ecosystem ecology, this study also provided metrics of home range size, habitat use, and movement behavior useful for conservation planning. </p><p> The first study provides a method for nutrient transfer mapping which could be applied to many other species, and leverages increasing quantities of high-resolution movement tracking data to map transfers of nutrients across landscapes. This can help predict the landscape-scale ecological changes resulting from the loss of animal movements that provide nutrient transfers. The approach can also be used to map other material transport dynamics, such as animal-transported seed dispersal or the movement of persistent organic pollutants. </p><p> In the second study, I used species distribution modeling to identify the interacting effects of climate and land use change on the distribution of <i>H. amphibius</i>. Hydrologic change is likely to result from ongoing shifts from rain-fed to irrigated agriculture across much of sub-Saharan Africa, where <i>H. amphibius</i> occurs. A lack of spatial data on hydrology, especially data temporally consistent with atmospheric climate datasets, has made it difficult to build species distribution models for semiaquatic species, such as <i>H. amphibius</i>, which are physiologically dependent on surface water. I overcame this challenge by coupling a simple hydrologic model to scenarios of land use and climate change, identifying potential effects on <i>H. amphibius</i> distributions. I found that increased levels of streamflow abstraction from irrigation will lead to much greater declines in <i>H. amphibius</i> habitat suitability than arise from scenarios of climate change alone. I also contrasted predictions of <i>H. amphibius</i> distributions that incorporated only atmospheric climate variables to predictions that also incorporated hydrologic variables, and found significant improvements in model performance when hydrology was incorporated. </p><p> The second study provides support for using predictive variables with strong mechanistic links to the physiology or ecology of the focal species when building species distribution models. The study also outlines a way to generate surfaces of key hydrologic variables from the climate surfaces commonly used for species distribution modeling. These surfaces have the potential to greatly improve forecasts generated by other semiaquatic species distribution models. From a conservation perspective, the second study highlights the potential for substantial losses of <i>H. amphibius</i> habitat across Africa as a result of increases in irrigation development. Other semiaquatic species in the region, as well as those dependent on the keystone ecological role of <i>H. amphibius</i> and its nutrient-transporting movements, may be similarly affected. </p><p> In the third study, I explored the role of movement in shaping species distributions in variable climates. Climatic variability at multiple time scales causes suitable climatic conditions to shift across geographic space. Recent scholarship has proposed that two species traits, the ability to colonize suitable locations, referred to as dispersal, and the ability to continue to occupy an area with unsuitable conditions, referred to as persistence, facilitate niche tracking, the process by which species follow suitable conditions moving through geographic space. By developing a model that simulates niche tracking through historically observed patterns of temporal and spatial variability, I quantified how different dispersal and persistence abilities affect niche tracking potential. I found that both dispersal and persistence facilitate niche tracking, and that small increases in persistence ability result in surprisingly large increases in niche tracking potential. </p><p> The third study makes two main contributions to ecological niche theory and distribution modeling. (Abstract shortened by ProQuest.) </p><p>

Habitat loss is the leading cause of species extinction. Protecting and managing habitat quality is vital to an organism’s persistence, and essential to endangered species recovery. We conducted an investigation of habitat quality and potential impacts from climate change to piping plovers (Charadrius melodius) breeding on the barrier island ecosystem of New York, during 2003-2005. Our first step in this analysis was to examined the relationship between two common measures of habitat quality: density and productivity (Chapter 1). We used both central and limiting tendency data analysis to find that density significantly limited productivity across many spatial scales, especially broader scales. Our analysis of plover habitat quality (Chapter 2) focused on (1) identifying the spatial scaling of plovers to their environment; (2) determining the relative importance of four aspects of the environment (land cover, predation, management, and disturbance); and (3) determining the key environmental variables that influence productivity. We found that plover habitat selection occurred within a narrow range of spatial scales that was unique to each environmental variable. Further, we found that management and predation variables influenced population-level productivity relatively more than land cover and disturbance. Environmental variables with a significant positive influence on habitat quality were land management units, plover conservation educational signs, and symbolic string fencing erected around plover nesting areas. We found a significant negative relationship among density of people on ocean beaches, herring gull density, and land cover degradation. To quantify possible impact to plover habitat from future climate change (Chapter 3), we examined the extent of habitat change resulting from different estimates of sea-level rise (SLR) and storminess over the next 100 years. We found that the particular SLR estimate, habitat response, and storm type used to model climate changes influenced the amount of potential habitat available. Importantly, we observed synergy between SLR and storms resulting in the increasing impact of SLR and storms on plover habitat over the next 100 years. Finally, we found that coastal development contributed considerably to habitat loss when combined with climate changes. Our findings raise concerns regarding current plover recovery goals and management strategies. Density-dependent productivity may threaten the goal of a joint increase in both plover population and productivity. We advocate density monitoring and allocation of alternative nesting areas to provide the relief of possible high-density limitations. Based on our analysis of habitat selection and climate change threats, we call for a shift in management focus away from known breeding areas, towards ecosystem processes. Long-term conservation of piping plover habitat quality is more likely through protecting and promoting natural barrier island dynamics (i.e. overwash and migration) and minimizing human development on the barrier islands of New York State.

No description available.

<p> Understanding how to balance human well-being and ecological integrity is one of the fundamental challenges in conservation and natural resource management. As our human-footprint on ecosystems expands and deepens, we are increasingly realizing that human well-being is crucial to understanding social-ecological systems and managing them sustainably.</p><p> In my first chapter I add to this literature by extending a theoretical model to examine the effects of two biophysical stressors on a marine species. While this model was developed to understand how harvest and climate change may interact to affect species viability, the model instead emphasized the sensitivity of the results to assumptions about human behavior. This result adds to a small, but growing, body of literature that demonstrates the importance of considering resource-users&rsquo; dynamics when attempting to predict outcomes for biophysical systems.</p><p> Despite conceptual advances in linking human-wellbeing to biophysical dynamics, a major challenge exists in operationalizing these conceptual framings. In my second chapter I use the US West Coast commercial fisheries system as a case study and developed a novel network approach of linking the social system (i.e. fishing communities) to the ecological system (the fish). This approach made use of data collected by management, making it immediately operational for all managed fisheries in the US. Such a conceptual framework represents a major step forward for mapping and quantifying these linkages between social and natural systems. I add to this work by analyzing these resultant networks to show that the topological structure and modularity varied non-randomly, providing additional features that may be useful for mangers seeking to balance human well-being with sustainable populations of fish.</p><p> In my third chapter I analyzed patterns of participation across the US West Coast commercial fisheries before and after a major management change in a single fishery. Using individual- and fishing community-level analyses, using the framework described above, I show that the policy affected how fishermen shift their effort across fisheries at the individual level, but community level attributes remain unchanged. This work demonstrates how such social-ecological system level policy analysis may be conducted.</p><p> Overall this dissertation helps move us towards a set of tools managers can use to evaluate policy efficacy in commercial fisheries in the face of rapid environmental change while balancing ecological integrity and human well-being.</p>

Climate change and the accompanying increase in global surface temperatures pose a major threat to freshwater ecosystems, especially at high latitudes where warming is predicted to be particularly rapid. To date many aspects of how rising temperatures can impact fresh waters remain unknown. Information about temperature effects on the level of communities, food webs, ecosystems is especially scarce. The few studies focusing on higher levels of organisation have used either laboratory microcosm experiments, which can lack realism or space-for-time substitution across large ranges of latitude, which can be confounded by bio-geographical effects. This study aimed to overcome these shortcomings by using a “natural experiment” in a set of 16 geothermally heated streams in the Hengill area, South-West Iceland, with water temperatures ranging from 4ºC to 49ºC (mean temperature). Data were analysed for two seasons, August 2008 and April 2009. The principal goal of this study was to assess the effects of temperature on the structure and functioning of food webs. Additionally the persistence of the community structures along the temperature gradient was examined through time (comparison of previously collected data in August 2004 and August 2008). Abundances of cold-stenotherm species decreased whereas those of eurythermal species increased with increasing temperatures leading to knock-on effects on abundances of other species. Species community overlap between streams declined as temperature difference between streams increased. The persistence of species composition through time was weakened at the extremes of the temperature gradient. Food webs showed a clear size structuring in analyses of trivariate food webs, abundance and biomass size spectra. Analysis of connectance, complexity, mean link length, mean 2-span, mean community span and slopes and intercepts of linear regressions fitted to the trivariate foods or size spectra revealed the impact of temperature change on freshwater ecosystems.

Climate change can have potentially catastrophic effects upon biodiversity and food web structure and according to the fourth IPCC report, ambient temperatures will rise by between 3.0-5.0 °C over the next century, with already an average increase in global surface temperature of ~0.74°C in the past 100 years. This has known implications in ecology from individuals to ecosystems. The microbial loop consists of small organisms ranging in body size from bacteria (1-15 μm), single-celled eukaryotes (10-1000 μm) and multicellular organisms (250 – 1000 μm) that assimilate dissolved organic carbon into the “classical food web”. ! The principal goal of this thesis was to assess how rising global temperatures might impact the natural microbial assemblages in 20 mesocosms under 2 treatments – 10 warmed (in line with IPCC predictions) and 10 ambient. The abundance and body mass of 4 major microbial loop taxa (desmids, flagellates, heterotrophic protists and meiofauna) were quantified at monthly intervals over a 2-year period. Secondly, in a microcosm experiment, the population dynamics of three pure cultures of ciliates were monitored across a temperature gradient; the rate of population decline under starvation and changes in body size were quantified.! Results showed that (1) rising global temperatures alters the size spectrum in the autotrophic protists, (2) temperature interacts with temporal and spatial gradients, resulting in changes in phenology (3) these changes in phenology are observable at both the community level and the population level within the microbial assemblage of the mesocosms and (4) extinction rates and body mass reduction in experimental microcosms were faster at warmer temperatures and partially support predictions of the metabolic theory of ecology.! The implications of these findings are discussed in terms of (1) continued research into the role that small organisms play in community and ecosystem ecologyand (2) the use of these small organisms in experiments as models to inform ecological theory by scaling up from microcosms and finally, (3) I discuss future directions in freshwater microbial ecology, focusing on the increased use of molecular techniques.

Exile is not only an appropriate lens through which to view the ecological, social, and psychological destabilizations of the Anthropocene, but also as a state which can inspire the flexibility and creativity necessary to survive difficult times through ecologically-connected states of being. Examinations of literary alienation and responses to this condition in this project are confined to women’s exoplanetary science fiction which anticipates the experience of physical and emotional separation from planet Earth. In contextualizing experiences of exile from our planet of origin and the expressions of such in women’s science fiction literature, this project interrogates selected cultural movements in human relationships to the environment, separation from the environment, and resistances to that estrangement through the concept of exile. Chapter One considers the Western myth of the lost paradise and the ways in which the Garden of Eden has contributed to Western conceptions of environmental and human perfection and belonging and the persistent idea of working one’s way back to Eden. In contrast to this idea, I present analyses of James Tiptree Jr.’s A Momentary Taste of Being and Molly Gloss’s The Dazzle of Day, both of which illustrate that working toward perfection is an ultimately stagnating and often violent move. Chapter Two, mounting further challenges to the Western paradise and its reverberations through environmental discourse, frames science fiction’s initial acquiescence to narratives of colonization and later feminist rejection of these narratives. Analyzing the connections between colonial structures, the environment, and beings considered nonhuman or less-than-human in Ursula K. Le Guin’s The Word for World is Forest and Joan Slonczewski’s A Door Into Ocean, this chapter describes the psychological and emotional estrangements necessary to survive and resist colonization and its ecological destruction and contextualizes experiences of exile. Chapter Two argues that though exile is often a destructive process, it can form a basis with which to resist entrenched social structures. Finally, Chapter Three examines the ways in which Indigenous science fiction, working in a different historical and cultural context than that of the Western feminist texts discussed in the previous two chapters, emphasizes an experience of and approach to exilic destabilizations which centres on what Gerald Vizenor calls “survivance”—the survival of colonial genocide and resistance to further colonial impositions. While Lee Maracle’s “The Void” and Mari Kurisato’s “Imposter Syndrome” utilize exoplanetary distance from Earth’s ecosystems to illustrate modes of survivance, they also demonstrate the ways in which relations to the land are maintained through interrelational rather than hierarchical subjectivities, and demonstrate the resilience intrinsic to interconnected ecological systems. In sum, the estranged position of women’s exoplanetary science fiction emerges as critical of the hierarchical structures which have resulted in widespread ecological collapse, and imparts the perspective necessary not only to challenge those structures but also to survive their destabilizations. / Dissertation / Doctor of Philosophy (PhD)

A combination of habitat loss, degradation and fragmentation are causing declines in butterfly species across Europe, with habitat specialists more vulnerable than generalists. The influence of climate change is serving to complicate matters, particularly at the edge of geographic ranges. Improving the quality of habitats is a key tool for the conservation of threatened species at both a local and landscape scale and this requires a thorough understanding of the ecology and habitat requirements of species. From this perspective this thesis examines and compares the ecology of two closely butterfly species, Polyommatus bellargus (the Adonis Blue) and Polyommatus coridon (the Chalkhill Blue) in southern England; calcareous grassland specialists, found in a highly fragmented ecosystem at the northern most edge of their geographic range. Chapter 2 explores whether there has been an expansion in the larval niche of P. bellargus due to a warming climate in recent decades, and finds no indication of change once concurrent local habitat change has been accounted for. Chapter 3 examines the role that differences in microhabitat requirements play in differentiating the larval niche of P. bellargus and P. coridon, showing P. coridon has broader microhabitat requirements. Chapter 4 experimentally examines the specificity of mutualistic interactions between the larvae of each butterfly species with the ants Myrmica sabuleti and Lasius niger. Chapter 5 uses microsatellites to explore the genetic structure of both P. bellargus and P. coridon, showing (as predicted) that P. coridon has a less fragmented population structure than P. bellargus, but both species have high levels of inbreeding.

The impacts of climate change on temperate forests are predicted to accelerate, with widespread implications for forest biodiversity and function. Remote sensing has provided insights into regional patterns of vegetation dynamics, and experimental studies have demonstrated impacts of specific changes on individual species. However, forests are diverse and complex ecosystems. To understand how different species in different forests respond to interacting environmental pressures, widespread ground-based monitoring is needed. The only practical way to achieve this is through the involvement of non-professional researchers, i.e., with citizen science. However, many techniques used to identify subtle changes in forests require expensive equipment and professional expertise. This thesis aimed to identify practical methods for citizen scientists to collect useful data on forest ecosystem dynamics in relation to climate change. Methods for monitoring tree phenology and canopy-understorey interactions were the main focus, as tree phenology exerts strong control on understorey light and forest biodiversity, and is already responding to climate change. The response of understorey vegetation to canopy closure in four woodlands from a single region of England (Devon) was examined in detail. These geographically close woodlands differed considerably in their composition and seasonal dynamics. The spring period was particularly important for herb-layer development, and small variations in canopy openness had important effects on herb-layer cover and composition. This work highlights the need to monitor a range of different woodlands at the regional scale, with sufficient resolution to pick up small but crucial differences through time. Citizen scientists could help to collect such data by monitoring herb-layer cover and changes in the abundance of key species, alongside monitoring the overstorey canopy. The spring leaf phenology of four canopy trees (ash, beech, oak and sycamore) were monitored intensively in one woodland using a range of methods: counts, percentage estimates and photography. First budburst and leaf expansion dates were compared with estimates of leaf expansion timing and rate, derived from time-series data using logistic growth models. Frequently used first-event dates were potentially misleading due to high variation in leaf development rates within and between species. Percentage estimates and counts produced similar estimates of leaf expansion timing and rate. A photo-derived greenness index produced similar estimates of timing, but not rate, and was compromised by practical issues of photographing individual crowns in closed canopy woodland. Citizen science should collect time-series data instead of frequently-used first event dates―visual observations offer the most practical way to do this, but further work is needed to test reliability with citizen scientists. Given high intra- and inter-species variation in tree phenology, whole forest canopies need to be monitored to infer canopy closure timing. Canopy openness was assessed using sophisticated hemispherical photography and a range of low-cost alternatives, across four Devon woodlands over a year. Visual estimates and ordinary photography were too coarse to identify fine-scale variation in canopies. Smartphone fisheye photography analysed with free software was identified as a reliable surrogate for estimating relative, though not absolute, canopy openness. The method has high potential as a citizen science tool, as different phone models and users gave similar canopy openness estimates. In a detailed follow-up study, smartphone fisheye photography, hemispherical photography and visual observations of leaf expansion were used every other day to characterise spring canopy development. Logistic growth models estimated canopy closure timing and rate. Visual observations identified much earlier canopy development than either photographic method. Smartphone fisheye photography performed comparably to hemispherical photography. There is good potential for practical application of smartphone fisheye photography, as similar canopy closure estimates were gained from photos taken once every two weeks. The research in this thesis identifies a range of methods suitable for widespread monitoring of forest ecosystem dynamics in relation to climate change. Developing a smartphone app for automatic analysis and submission of canopy images will be an important next step to enabling widespread use. A pilot project is underway to begin testing methods with citizen scientists. Further research into data quality with citizen scientists is needed before the methods can be rolled out widely with confidence.

This study addresses the regulation of large river phytoplankton by climate-related drivers with the help of three different approaches, i.e. analyses of long-term data and spatial dynamics (longitudinal samplings) as well as mathematical modeling. The central hypothesis is that discharge has a dominant role among climate-related variables which strongly alters phytoplankton biomass development. A multi-factorial statistical analysis on the basis of long-term data (1990 – 2009; 1994 – 2009) from two measuring stations of the rivers Rhine and Elbe revealed that discharge conditions and light availability were the main driving forces regulating phytoplankton spring bloom dynamics. For the Rhine, a trend towards an earlier occurrence of the spring bloom event and a decrease in seasonal mean phytoplankton biomass could be detected, whereas for the Elbe no shift in the timing of the spring bloom and a tendency towards increasing seasonal mean phytoplankton biomass was found. Longitudinal sampling campaigns served to analyze the spatial plankton development on a short-term scale. River-internal growth and loss processes, as well as import mediated by tributaries were examined. Four longitudinal profiles were realized at different seasons in recent years (2009 – 2011) and it was revealed that tributaries mainly had a diluting impact on plankton densities in the Elbe and provided an additional import of phyto- and zooplankton densities in the Rhine. In the present study, high bivalve abundances were detected in the Rhine, probably leading to river-internal losses of phytoplankton which could compensate phytoplankton production resulting in low phytoplankton concentrations. In the Elbe, low abundances of bivalves and a low benthic grazing pressure prevailed. On the other hand, an unusually low discharge event in spring 2011 in the Rhine demonstrated that loss processes can at times be superimposed by strong phytoplankton production leading to extremely high phytoplankton biomasses and chlorophyll a values. Hence, despite the observed long-term trend of decreasing chlorophyll values in the last two decades, extreme environmental conditions can provoke regime shifts with exceptional phytoplankton mass developments. To assess the potential impacts of future climate change on water quality, the water quality simulation model QSim was used to establish a model for the free-flowing part of the Rhine. The modeling approach was implemented by changing the hydrological and climatologic input data according to different climate projections for the near (2021 – 2050) and the far future (2071 – 2100). The model results indicated a weak response of phytoplankton biomass in the Rhine towards altered climatic conditions, including discharge reductions and water temperature increases. The study suggests that changes in discharge rather than water temperature mediate climate change effects on large river phytoplankton. However, the effects are river specific as a consequence of system specific differences in main control mechanisms (e.g. ‘bottom-up’ versus ‘top-down’). / Anhand von drei verschiedenen Ansätzen analysiert die vorliegende Arbeit die Regulierung von Phytoplankton in großen Flüssen durch klimabedingte Faktoren: Auswertung von Langzeitdaten, räumliche Dynamik (fließzeitkonforme, longitudinale Beprobungen) und mathematische Modellierung. Die zentrale Hypothese ist, dass Abfluss eine dominante Rolle unter den klimabedingten Faktoren spielt und die Phytoplanktonbiomasse stark beeinflusst. Eine multifaktorielle statistische Analyse basierend auf Langzeitdaten (1990 – 2009; 1994 –2009) von zwei Stationen der Flüsse Rhein und Elbe zeigten, dass hauptsächlich Abflussbedingungen und Lichtverfügbarkeit die Antriebskräfte bei der Regulierung der Phytoplanktonfrühjahrsblüte darstellten. Während sich am Rhein ein Trend hin zu einem früheren Auftreten der Frühjahrsblüte und einer Abnahme der mittleren Phytoplankton-biomasse während der Vegetationsperiode zeigte, konnte für die Elbe keine zeitliche Verschiebung der Frühjahrsblüte festgestellt werden und mittlere Phytoplanktonbiomassen zeigten hier eine steigende Tendenz. Longitudinale Fließzeitbeprobungen dienten zur Analyse der kurzfristigen räumlichen Entwicklung des Planktons. Interne Produktions- und Verlustprozesse, sowie der Eintrag durch Zuflüsse wurden untersucht. Vier longitudinale Profile wurden zu unterschiedlichen Jahreszeiten der letzten Jahre (2009 – 2011) realisiert und es wurde gezeigt, dass die Nebenflüsse der Elbe vorwiegend einen Verdünnungseffekt auf die Planktondichten des Hauptstromes hatten, während sie für den Rhein einen wichtigen zusätzlichen Eintrag von Phyto- und Zooplankton darstellten. In der vorliegenden Arbeit wurden hohe Muscheldichten im Rhein gefunden, die möglicherweise zu hohen internen Planktonverlusten durch Fraß beigetragen haben, und somit zu niedrigen Phytoplankton-konzentrationen geführt haben könnten. In der Elbe waren die Muscheldichten dagegen gering und somit war auch der benthische Fraßdruck niedriger. Auf der anderen Seite zeigte ein ungewöhnlich niedriges Abflussereignis im Frühjahr 2011 am Rhein, dass diese Verlustprozesse zeitweise von starker Phytoplanktonproduktion überlagert werden können und dadurch extrem hohe Phytoplanktonbiomassen und Chlorophyllwerte entstehen können. Demzufolge können trotz der Beobachtung eines langfristigen abnehmenden Trends in den Chlorophyllgehalten während der letzen zwei Jahrzehnte extreme Umweltbedingungen einen Regime-shift mit außergewöhnlichen Massenentwicklungen des Phytoplanktons hervorrufen. Um den möglichen Einfluss des zukünftigen Klimawandels auf die Gewässergüte abzuschätzen, wurde mithilfe des Gewässergütesimulationsmodells QSim ein Modell für den frei fließenden Abschnitt des Rheins erstellt. Für den Modellierungsansatz wurden die hydrologischen und klimatologischen Eingangsdaten entsprechend der verschiedenen Klimaprojektionen für die nahe (2021 – 2050) und ferne Zukunft (2071 – 2100) verändert. Die Modellergebnisse zeigten, dass sich Änderungen in den klimatischen Bedingungen, einschließlich Abflussreduktion und Wassertemperaturanstieg, nur geringfügig auf die Phytoplankton¬biomasse des Rheins auswirkten. Die vorliegende Arbeit deutet darauf hin, dass Klimawandeleffekte eher durch Änderungen der Abflussverhältnisse auf das Phytoplankton in großen Flüssen wirken als durch Änderungen der Wassertemperatur. Der Effekt ist jedoch flusssystemspezifisch, da die Auswirkungen von systemspezifischen Unterschieden in den Hauptkontrollmechanismen gesteuert werden (z.B. ‚Bottom-up’ versus ‚Top-down’).