Nutrient retention is governed by the interplay between physical processes that control the throughput of water and materials (i.e., water residence time), and by biological processes that govern transformation and uptake (e.g., microbial denitrification). A partial breach of the dam located on Kimages Creek (VA) re-established the historical (pre-1920) connection to the James River and provided a well-defined channel to gauge tidal exchange. We quantified tidal exchange as well as non-tidal (watershed) inputs on a monthly basis to assess Nitrogen (N) retention. Water and N fluxes were dominated by tidal exchange which was typically three times greater than inputs from the upper watershed. Exchange volumes varied by 20-fold in response to seasonal variation in water elevation of the James River Estuary. Comparison of input and output fluxes suggest that the tidal segment of Kimages Creek acted as a source of dissolved inorganic N in the winter and a N sink in other months. Seasonal variation in N retention was significantly related to water temperature and estimates of ecosystem metabolism derived from diel dissolved oxygen data.

Doctor of Philosophy / Department of Geography / Lisa M.B. Harrington / The Greater Yellowstone Ecosystem (GYE) is a large, nearly intact ecosystem with significant protection that has often been considered an ideal location to examine coupled human-environment interactions due to the region’s complex mosaic of private and public lands, competing natural resource uses, and rapid population growth. A transition toward sustainability suggests that current societal and economic needs can be met while simultaneously maintaining the planet’s life support systems for future generations. To facilitate sustainability transitions it is imperative that the perceptions and experiences of local communities be documented. The objective of this study was to determine how residents of amenity-driven gateway communities (West Yellowstone and Red Lodge, Montana, and Jackson, Wyoming) surrounding Yellowstone and Grand Teton national parks perceive and experience their transition toward sustainability and the challenges inherent in that transition, how those perceptions inform locally produced and extra-local policies, and how institutions influence sustainability goals. Further, this study determined which factors contribute to these perceptions, and whether they differed spatially and temporally. To meet study objectives, a mixed methods approach was implemented, including the content analysis of local newspapers and key informant interviews. Content analysis of local newspapers was used to investigate decision maker and stakeholder priorities for the local and regional environment, economy, and communities, and to determine what actions had been taken to promote sustainability. A total of 193 articles from West Yellowstone News, 287 articles from Carbon County News, and 333 articles from Jackson Hole News & Guide for the ten year period 2000-2009, were analyzed. Specific focal topics varied among the newspapers/communities, but in general terms the most discussed topics in West Yellowstone during this time were focused on natural resources, economic development, community development, sustainability and conservation, and growth and development. The most discussed topics for Red Lodge were community development, government services, tourism and recreation, and growth and development. The most commonly discussed topics in Jackson were natural resources, growth and development, community development, and government services. A total of 35 semi-structured interviews were conducted with key informants in the three study communities during the summer of 2010 to allow for specific questioning and to gain additional information. Definitions of sustainability differed based on the key informant’s community, role in the community, and length of residence in the community. Overall, definitions of sustainability focused on the environment, the economy, and multi-generational or long-term thinking. The prioritization of the economy, environment, and society also differed based on community; however, there was overall recognition that each community was dependent upon the natural environment for economic vitality. In all three study communities, dependence on tourism and recreation-based industries, the lack of a diversified economy, and continued growth and development have resulted in a disconnect between perceptions, priorities, and goals as they relate to sustainability. In addition, each community was focused on multiple goals that further complicated the fulfillment of sustainability objectives. The multi-goal orientation of study communities is reflected in the multiple visions that various decision makers and stakeholders have for the community and their futures. What is needed most is a hierarchical approach to a sustainability transition, with each community setting its own, as well as ecosystem-wide, goals, objectives, and visions. Findings suggest that a transition toward sustainability is perceived and experienced differently based on local context. In the GYE, that context includes a tourism-based economy that is dependent upon the natural environment, a myriad of local, regional, national, and global stakeholders, and the presence of federal land agencies that are responsible for the sustainability of natural systems, freeing local communities to focus on the societal and economic dimensions of sustainability. A transition toward sustainability will be manifested differently in the Greater Yellowstone Ecosystem, and potentially other communities adjacent to protected lands, than it is other areas because of its unique milieu. While the close proximity of federal lands, including Yellowstone National Park, may complicate the sustainability discourse at times and may, in certain instances, add additional challenges through extra-local control of change, these same federal lands may also favor a transition toward sustainability in amenity-driven gateway communities. In addition, the disparate socio-economic conditions present in study communities, as well as extra-local institutions and agencies, directly influence, and may at times further complicate, a transition toward sustainability. This study is based on the theory that in order to successfully transition toward sustainability, a better understanding of coupled human and natural systems is critical, and because of the close couplings between human and natural systems in the Greater Yellowstone Ecosystem, and because of the unique challenges and conflicts present in the region, the GYE is an ideal location to study human-environment interactions. The use-inspired orientation of sustainability science aims to provide tangible, real-world, and place-based understanding of a transition toward sustainability. The contribution of this study to the field of sustainability science is the understanding that, while sustainability visions, goals, and objectives may be similar across a region, consideration of local contexts affecting goals and perceptions provides valuable insights that may inform sustainability pathways at local scales and, as a result, provide deeper understanding of global sustainability. One of these insights is that communities that seemingly have much in common due to their shared region, physical environmental surroundings, and history, the specific concerns to ensure place-based sustainability can show variability. Another important point from this research is that, while most depictions of sustainability are focused on three elements—the economy, society, and the environment—individuals also key in on multigenerational concerns.

Biodiversity loss is one of the major threats to humanity. This has led to an increasing amount of research on biodiversity on genetic and species levels. Studies of diversity at the ecosystem level has however been neglected. An important aspect of ecosystems is food webs that describe the predation-prey interactions between species. Properties explaining the topological structure of food webs can be used to compare and highlight differences between ecosystems. In the present study, topological network properties are used to compare the diversity of network structures between groups of empirical food webs. Differences between 45 aquatic and 45 terrestrial food webs are compared as well as the effects of species richness on lake network structure diversity. Network structure diversity is measured as the average Euclidean distance from food webs to their group centroid in a multidimensional space of network properties. While the average network structure differs between aquatic and terrestrial food webs, no significant difference in variation is found. For 128 Swedish and 48 North American lake food webs, increasing species richness is shown to decrease network structure diversity. A higher diversity of network structures could potentially indicate a more ways to cope with disturbances or provisions of a higher variety of ecosystem services. Preliminary tests of ecosystem diversity effects on stability were conducted but proved inconclusive.

Magister Artium - MA / This thesis investigates the influence of climate change and climatic variability on wetland ecosystems (coastal and inland wetlands) on the Agulhas coastal plain. Firstly, this research examines coastal wetland ecosystem resilience to sea level rise by modelling sea level rise trajectories for the Droё River wetland. The rate of sediment accretion was modelled relative to IPCC sea level rise estimates for multiple RCP scenarios. For each scenario, inundation by neap and spring tide and the 2-, 4- and 8-year recurrence interval water level was modelled over a period of 200 years. When tidal variation is considered, the rate of sediment accretion exceeds rising sea levels associated with climate change, resulting in no major changes in terms of inundation. When sea level rise scenarios were modelled in conjunction with the recurrence interval water levels, flooding of the coastal wetland was much greater than current levels for the 1 in 4 and 1 in 8 year events. The study suggests that for this wetland, variability of flows may be a key factor contributing to wetland resilience. Secondly, the thesis examines the variability of open wetland water surface areas and their relation to rainfall to determine wetland hydrological inputs for the Nuwejaars wetland system and respective wetlands. A remote sensing approach was adopted, Landsat 5 TM and 8 OLI multispectral imagery were used to detect changes of water surfaces for the period 1989 to 2017. Water surfaces were enhanced and extracted using the Modified Normalized Difference Water Index of Xu (2006). The coefficient of variation of wetland water surface area was determined. The variability ranges from low to high for respective wetlands. A correlation analysis of wetland water surfaces and local and catchment rainfall for the preceding 1, 3, 6, 9, 12 and 24 months was undertaken. The preceding month and associated inputs explains the annual variability of surface waters. The study suggests that, the variability of wetland water surface area are related to variations to water inputs and groundwater, as well as variations in water outputs such as evapotranspiration and an outlet channel.

Philosophiae Doctor - PhD / Although jellyfish are recognised recently as key components that can influence ecosystem functioning and trophic flows in the northern Benguela upwelling ecosystem, the number of published studies on their abundance, seasonality, life history and ecological roles off Namibia is strictly limited. Chrysaora fulgida is one of the most common and conspicuous medusae in the plankton off Namibia, and has flourished in the region, following the decline of the pilchard fishery at the end of the 1960s. It is said that their biomass (together with Aequorea forskalea) exceed that of the commercially important fish stocks off Namibia. In addition, this species is also capable of forming large swarms in northern Benguela where they are a nuisance to fisheries operations. The objective of this study is to try and fill gaps regarding our knowledge of the biology and ecology of Chrysaora fulgida off Namibia, with a view to improve our understanding of its success in the northern Benguela ecosystem. In the Chapter 1, a general overview on the current knowledge and population dynamics of jellyish blooms and their ecology is compiled. Other key topics of the thesis such as jellyfish life cycles and their reproduction are also introduced. Chapter 2 investigates the temporal changes in the jellyfish community in Walvis Bay over a 23-month period from biweekly plankton samples. All twelve of the recovered taxa were characteristically neritic, and included meroplanktonic Hydrozoa and Scyphozoa, as well as cydippid ctenophores and shallow water siphonophores. Whilst, ephyrae of Chrysaora fulgida were dominant overall, and peaked in abundance during mid-spring (Year 2012: 168 933 ind. 100 m-3) and late winter (Year 2013: 23 389 ind. 100 m-3), they were not present all year round, being replaced (in part) by Obelia in summer and autumn, Bougainvillia in spring and summer, and Muggiaea atlantica in summer. Seasonal changes in the composition and structure of the community were driven primarily by bottom water temperature and day length (explaining 24% of the variability in community structure), with wind speed and moon illumination playing a secondary role. The recruitment of ephyrae of C. fulgida to the plankton off Walvis Bay is confirmed not to be continuous throughout the year. Chapter 3 present the first detailed investigation on the identification, morphological development and growth of wild caught ―ephyrae‖ of the scyphozoan Chrysaora fulgida and Chrysaora africana in Walvis Bay, off Namibia. Concrete morphological dissimilarities are documented to distinguish C. africana from C. fulgida, despite the limited sample size of C. africana: coloration differences and the presence/absence of branched canals on the periphery of velar and rhopalial canal tips. In the case of C. fulgida the morphological development from an ephyra (Stage 0) to a juvenile medusa could be described successfully in six stages, whilst missing stages were noted for C. africana. In general, the development of ephyrae described here agrees with patterns described for other species in the genus from elsewhere. The ephyrae stages of C. fulgida illustrated a low overall growth rate (4.33 and 3.45% d-1, respectively) and longer ontogenic development (~164 days), respectively, than most other jellyfish species. Through the histological examination of medusa gonads, Chapter 4 investigates the sexual reproduction and maturation of both Chrysaora species, collected off Walvis Bay, Namibia. Both species were non-brooding, gonochoristic, displayed a 1:1 sex ratio and exhibited no clear sexual dimorphism features. Gametogenesis in both species was similar to that displayed by other Discomedusae, whilst some differences in gonad maturity were evident between them – Chrysaora fulgida displayed aseasonal, reproductive heterogeneity (maturing at ~300 mm diameter) and individuals were semelparous, whilst C. africana appeared strongly seasonal but iteroparous. Through stable isotope analysis (𝛿13C, 𝛿15N and C:N ratios), Chapter 5 examines the presence of tissue, ontogenetic, seasonal, spatial and interspecific variability in medusae of Chrysaora fulgida and Chrysaora africana off Walvis Bay, in the northern Benguela, Namibia. This study did not only illustrate size-associated shifts in trophic ecology, but also revealed spatial, inter-species and some tissue differences in the northern Benguela upwelling system. Size would appear to be the over-riding factor that influences the isotope signatures of Chrysaora fulgida; size being linked in turn to space. A clear negative relationship is illustratred between 𝛿15N and individual size for two scyphozoans (C. fulgida and C. africana) off central Namibia, indicating that larger jellyfish feed lower down the food chain than smaller ones in both species. This is explained by the need and ability of ephyrae and small medusae to access the microbial food web which consists of many trophic steps and hence numerous opportunities for enrichment of nitrogen isotopes, resulting in higher 𝛿15N values of smaller individuals. Chapter 6 provides a synthesis of the main findings of the thesis, and makes recommendations on ways that the research can be carried forward. / 2020-08-31

Increases in agricultural intensification over the past century have resulted in significant alterations to the rural landscape across the Midwest. Pollinators are essential to sustain natural and managed ecosystems. They are vital for food production and their declines have been linked, in part, to a rise in intensive agricultural practices. There is a recognized need among numerous stakeholders to build sustainability into the management of agroecosystems to protect both the biotic and abiotic resources of these systems. The use of cover crops is gaining interest among agricultural producers for benefits such as improving water quality and soil health. Cover cropping systems have the potential to provide floral resources to pollinators and suppress problematic driver weeds. The overall objective of this study was to quantify the effects of cover crops on plant and pollinator biodiversity within agricultural systems. This study aimed to characterize the pollinator diversity indicative of the patchwork mosaic forest-agroecosystem of Crab Orchard National Wildlife Refuge; evaluate the roles cover crop treatments play in supporting pollinator diversity and weed suppression benefits in a conventionally managed system; and provide the basis of recommendations for sustainable weed suppression tactics and for enhancing the quality of pollinator habitat within agricultural systems.

O objetivo do presente estudo foi levantar o modelo de formação do ecossistema de inovação que orbita as incubadoras integrantes da rede alvo, AGROINNCUBA, identificando as variáveis que compõem o ecossistema e avaliando a resultante deste processo no desempenho de empresas inovadoras voltadas para o agronegócio. A fim de caracterizar o modelo de formação de cada ecossistema de inovação da rede, a metodologia utilizada foi baseada em pesquisa quantitativa (análise multivariada) com os Coordenadores e empreendedores das incubadoras filiadas à AGROINNCUBA, através de um questionário com respostas abertas e fechadas aplicado online via Google formulários, além de entrevistas com os gestores das incubadoras e parques participantes. Os atores dos ecossistemas de inovação da rede AGROINNCUBA, têm desenvolvido uma cultura direcionada a inovação, dedicando-se a pensar e agir de forma a gerir o conhecimento por meio da tecnologia da informação, da organização do trabalho, da gestão da inovação, gestão de pessoas e de recursos, possibilitando assim ambientes que estimulem a criatividade, a viabilização de talentos, contribuindo para o seu desenvolvimento e fortalecimento. Diante do levantamento realizado para a verificação da existência de um ecossistema de inovação estabelecido ao redor das incubadoras e parques científicos da rede AGROINNCUBA, pode-se afirmar que este conjunto de atores tem contribuído para a geração de novos negócios inovadores, assim, promovendo o desenvolvimento econômico e social. / The objective of the present study was to analyze the formation model of the innovation ecosystem that orbits the incubators of the target network, AGROINNCUBA, identifying the variables that compose the ecosystem and evaluating the resulting process in performance of innovative agribusiness companies. In order to characterize the formation model of each innovation ecosystem, the methodology used was based on quantitative (multivariate analysis) and qualitative (discourse analysis) research with coordinators and entrepreneurs from the incubators affiliated with the AGROINNCUBA, through a questionnaire with open and closed responses applied online via Google forms and interviews with the managers of the participating incubators. The actors of the innovation ecosystems of the AGROINNCUBA network, have developed a culture directed to innovation, dedicating themselves to thinking and acting in order to manage knowledge through information technology, work organization, Innovation management, Management of people and resources, thus enabling environments that stimulate creativity, the feasibility of talents, contributing to their development and strengthening. In view of the survey carried out to verify the existence of an innovation ecosystem established around the incubators and scientific parks of the AGROINNCUBA network, it can be affirmed that this set of actors has contributed to the generation of new Innovative business, thus promoting economic and social development.

Digital transformation is an area of research that has received a lot of attention in recent years. When talking about it in the context of entrepreneurship, digitalization is changing business interactions as well as completing different tasks. Since the businesses are not working in isolation, but can be rather seen as part of complex ecosystems interacting with different stakeholders, there is an unexplored research area regarding digitalization of ecosystems. The purpose of this research is to extend the literature on value creation and delivery within complex multi-stakeholder ecosystems using digital platforms and the change in the roles and responsibilities of stakeholders. The empirical research is based on qualitative approach utilizing case-study to investigate how the roles and responsibilities of an ecosystem have changed via semi-structured interviews. The findings indicate that digitalization changes the ecosystem by optimizing the existing interactions between different stakeholders as well as enabling stakeholders to take new roles on the digital platforms. Roles were impacted in terms of power and leadership over the ecosystem, but to a larger extent there was a shift in how stakeholders carried out their responsibilities. Additionally, digital technologies change the responsibilities by automation as well as taking over certain roles in the form of machine learning algorithms.

Shortened periods of inundation due to water management have led to the encroachment and expansion of Carolina willow (Salix caroliniana) in sawgrass (Cladium jamaicense) marsh communities. Morphologic and physiologic differences between sawgrass and willow have potential consequences for microhabitat conditions and ecosystem function such as a reduction in temperatures and light availability and changes in primary productivity. Since it is a woody shrub, willow is often assumed to exhibit higher rates of transpiration than non woody plants, which in turn can affect photosynthesis and carbon exchange and ultimately wetland water management. In this study willow was found to have higher rates of stomatal conductance (gs) and photosynthesis (Anet) than sawgrass. However, sawgrass had greater intrinsic water use efficiency (WUE) than willow. This suggests that willow is capable of greater gas exchange and carbon assimilation than sawgrass but requires more water. Understanding the implications of willow expansion will improve landscape models of wetland water and carbon exchange and inform water management decisions. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Thesis advisor: David Krauss / In an attempt to better understand the biodiversity of an urban ecosystem, we have conducted plant and bird biodiversity assessments of 10 sites in the Greater Boston area from September 2002-April 2003. These sites have been identified by the Urban Ecology Institute as important green areas through the Natural Cities Program. The purpose of this program is to create a greater body of knowledge of urban green spaces and the greater urban ecosystem of Boston. Our objective was to quantify plant and bird biodiversity by focusing on species richness. We then compared this biodiversity information to various factors such as area of impervious surface, and area of maintained lawn. Our analysis did not demonstrate statistically significant relationships between these factors. / Thesis (BS) — Boston College, 2003. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Biology. / Discipline: College Honors Program.