Anthropogenic stressors are increasingly changing conditions in coastal areas and impacting important habitats. But, when multiple stressors act simultaneously, their effects on ecosystems become more difficult to predict. In Chesapeake Bay, USA, predictions suggest that anthropogenic stressors from climate change, such as warming temperatures, may increase the frequency and severity of storm events, leading to increased freshwater, nutrient, and sediment inputs. Coastal development, another source of anthropogenic stressors, continues to increase with growing coastal populations, and may lead to altered sediment characteristics, habitat fragmentation, altered food webs, and loss of vegetated habitats. Community processes may interact with stressors, for example, immigration of propagules between habitat patches may alter diversity, and modify community response to stressors. Changes in biodiversity might alter ecosystem functioning and services, but diverse ecosystems may be more stable especially in the face of multiple stressors. Many habitats are vulnerable to anthropogenic stressors, including seagrass systems, which provide many valuable ecosystem services. Understanding how multiple stressors and community processes interact now is key to maintaining ecosystem services in the future. Using a model seagrass (Zostera marina) system, I tested the effects of multiple stressors and their interactions with crustacean grazer immigration and diversity on ecosystem properties in a series of fully-factorial mesocosm experiments. I found that despite grazer species having varied responses to individual stressors, grazing pressure was largely maintained in spite of multiple stressors. More diverse grazer assemblages generally stabilized epiphytic algal biomass in the face of stressors, thereby increasing the resistance stability of this important component of the fouling community. Immigration of crustacean grazers did not interact significantly with stressors, and had little effect overall except to increase grazer biomass. Stressors generally reduced primary producer biomass, although in some cases they favored epiphytic algae. Generally, I did not find interactions among stressors and grazer immigration or diversity, even though diverse grazer assemblages stabilized epiphytic algal biomass. to assess potential impacts of coastal development, I surveyed twenty seagrass beds in lower Chesapeake Bay, VA and assessed local shoreline development effects on adjacent seagrass beds. I sampled primary producers, consumers, water quality, and sediment characteristics in seagrass beds, and characterized development along the adjacent shoreline. I found that development significantly affected sediment characteristics, while epifaunal and epiphytic algal biomass was significantly higher on the Western versus the Eastern side of the bay. Grazer and predator biomass did not differ with either development or bay region. Thus, in seagrass communities, various factors appear to drive sediment and biological community properties on different spatial scales. This may be an important consideration for management, because efforts that incorporate spatial scales of ecosystem processes will likely have more impact. Overall, these results suggest that stressor impacts in seagrass ecosystems generally do not interact but are sometimes context specific, while grazer diversity may have a limited but potentially important role in buffering certain ecosystem properties again stressors. Different factors appear to influence ecosystem properties at various spatial scales, an important consideration for predicting future impacts of multiple anthropogenic stressors in submerged vegetated systems.

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Seeding deteriorated range lands efficiently and economically has become one of the most promising means of improving the agricultural economy of the western range states. By providing the most rapid means of increasing the quantity and improving the quality of forage for livestock, and aiding in the prevention of soil erosion, artificial seeding contributes directly to the stability of agriculture.

The particular purpose of this study was to determine the effects of large-scale sagebrush reseeding projects on sage grouse populations and whether such effects were partly or entirely beneficial, neutral, or detrimental to the survival of such populations. During two seasons of field work, the studies initiated on a short-time basis had the following specific objectives: To compare the utilization by sage grouse of reseeded and non-reseeded lands for the seasonal activities of mating, nesting, raising a brood, fall coveying, and wintering. To compare the utilization by sage grouse of reseeded and non-reseeded lands for daily activities of feeding, watering, resting, hiding, and roosting. To determine fall and winter movements of the grouse in relation to reseeded lands. To determine the food and cover available to grouse on randomly selected sample plots To arrive at an index to food preferences through comparison of stomach analysis and food availability studies. To determine the effect of livestock grazing of reseeded lands on sage grouse. To determine the effect of plant succession on availability of food and cover within reseeded lands.

Pentachlorophenol (PCP) is one of the prominent environmental pollutant that has penetrated into food chain and is present in humans. Health concerns have been raised since daily intake of PCP by the US population is estimated to be 16-19 µg. PCP facilitates dissipation of electrochemical potential gradients of hydrogen ions across energy transducing membranes, which are the energy sources for the conversion of adenosine diphosphate into adenosine triphosphate. Closely linked to these dissipative effects is the development of electrical conductivity in lipid membranes, induced by the presence of PCP. Three modes of PCP - induced membrane electrical conductivity were theoretically analyzed and experimentally verifiable formulations of each models were developed. Experimental studies using the charge - pulse method involved characterization of the time dependent transmembrane voltage over a wide pH range, from 1.8 to 9.5, for 30 µM concentrations of PCP. Lipid membranes were prepared from dioleoyl phosphatidylcholine. It was shown that three PCP molecular species were determining the transmembrane transfer of hydrogen ions: electrically neutral PCP molecules (HA), negatively charged pentachlorophenolate ions (A⁻) and negatively charged heterodimers (AHA⁻). It was found that at pH>9 the membrane electrical conductivity was determined by the transmembrane movement of A⁻ ions, whenever pHAHA⁻ species. Two new membrane surface reactions were proposed as supplementary mechanisms for the generation of AHA⁻ in addition to the formation of AHA⁻ by the recombination of HA and A⁻, HA + A⁻→ AHA⁻. These new reactions are, (i) 2HA → H⁺ + AHA⁻, and (ii) H20 + 2A⁻ → OH' + AHA⁻. Reaction (i) provides formation of membrane permeable heterodimers AHA⁻ at pH < < 5.5 and reaction (ii) at pH> > 5.5. The maximum surface density of AHA" heterodimers was 0.09 pmol/cm² • The rate constant of formation of AHA' by recombination, HA + A⁻ → AHA' was estimated to be k[subscript f] = 2.6xl0⁹ cm² mol⁻¹ s⁻¹ and the dissociation rate constant for AHA⁻ Further, it was possible to determine the rate constants of transmembrane translocation for A' and AHA⁻ ions to be k[subscript a] = 6.6x10⁻⁵ s⁻¹ and k[subscript aha] = 1200 S⁻¹, respectively.

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Commerce, Law and Management, Wits Business School, 2016. / This study contends that Information Systems and Technologies (ISTs) fail to adequately provide for effective delivery of Business Intelligence and Analytics (BIA), which limits the value that organisations can derive from their data assets. In spite of the influence that each has on the other and their widely acknowledged and undisputed relationship and interdependencies, design and development approaches still promote a silo approach to IST and BIA in theory and practice. The evolution of the role of data in the digital economy not only compels academics and practitioners to collaborate on how to enable creation of good quality data at source but intensifies the requirement for an integrated approach to IST and BIA design. The research problem that the study addresses is that design methods commonly employed in both Information Systems (IS) research studies and practice do not advocate for an integrated approach to design and development of IST and BIA. While IS research accounts for both IST and BIA, IST and BIA design and development studies are approached independently and/or in isolation, with limited integration. The effectiveness of Social informatics (SI) as an interdisciplinary study of design, uses and consequences of use, puts it above the rest of the commonly applied socio-technical design theories and approaches. SI’s strength is in studying designs, uses and consequences of IST use after implementation. However, the theory versus practice inconsistencies presented by the interpretivist paradigm, which is an underpinning philosophy for classical SI, limit its use as a design method. Critical Realism (CR) offers the research study a viable alternative and is crucial in addressing both contextual requirements, while embracing the positivist, deterministic aspects of the study. CR is a pluralist approach based on sound research method principles; hence the study adopted it as both the theoretical paradigm and research method. The research study objective is to reconceptualise the SI perspective as an integrative design method underpinned by CR. The study adopts CR as its research methodology. CR is a philosophy of science that allows for the pluralistic approach to operationalisation of the research strategy, a catalyst in addressing the paradigmatic challenges of the research study. The ability to address the qualitative realist requirements of the study while effectively dealing with the positivist characteristics of the research was crucial in ensuring comprehensive results. The insights which could only be effectively gained through a qualitative realist process of enquiry were invaluable in advancing the IST and BIA design knowledge and practice. CR’s strength in focusing the research practice on the complexities of the real world is a critical enabler for an open system discipline such as IS. It ensures that the research is placed within the realist context of time, space and culture. CR is effective in allowing the researcher to explain the mechanisms that influence the social actor action at different levels of social organisations. It allows for the identification of non-deterministic tendencies in a complex, multidisciplinary and open system such as IS. It not only accounts for the varying social actor requirements at empirical level but reveals possible underlying causes and relationships of the observable or non-observable events and/or activities at play. This approach to analysis of IST and BIA requirements offers a unique ability to frame problems in meaningful and social actor-centred ways, at all levels of social organisation, enabling design and development of IST that are BIA centric. The development of new knowledge advances the field of IS design, a crucial step towards offering practitioners with a practical, structured and integrative design method. The critical realist approach is the most appropriate theoretical paradigm to adopt to address the theory-practice inconsistency challenges at the heart of the IS field. Its strength as a research methodology offers the researcher a unique ability to interact with data at a level that other research methods do not: that is, to examine the impact of data at the three fundamental levels of research – empirical, actual and real – thereby enhancing the effectiveness of its application in practice. Therefore, reconceptualisation of the SI perspective theoretical paradigm from interpretivism to CR offers greater benefits not only to this research study but to the IS field. This is yet another development in the field which seeks to address the long-standing challenge of IS value contribution that is constantly diminished by ineffective design methods and poor integration of the IST and BIA disciplines, which by design should be leveraging on each other’s strengths in a quest to deliver superior results to businesses. Business requirements analysed as input into the design process using the integrative CR-based design method account for BIA requirements, thus enhancing value derived from both IST and BIA. / MT 2017

Participatory, collaborative modeling processes represent a unique decision-making technique within natural resources management that allows for the combination of stakeholder involvement with the analytical and predictive power of scientific models. The continued use of participatory modeling within decision-making processes depends in part upon the willingness of stakeholders to participate. Continued participation of stakeholders is key to the persistence and overall success of these processes, and yet limited information exists concerning the impacts of these processes on participants. The consideration of human dimensions advances our understanding of the design and function of participatory modeling processes, including their ability to create consensus outcomes, their capacity to integrate natural and social sciences, and their capability to advance sustainable natural resources policy and management. Within this thesis, I analyzed stakeholders’ advice and communication social networks and their attitudes towards scientific models to better understand the impact of these participatory modeling processes on participants. I found that the development of group cohesion was more heterogeneous than previously thought. While there was a significant increase in advice ties between OysterFutures members, silos of advice within stakeholder groups remained. There was also a high level of between-stakeholder group advice ties that existed prior to the OysterFutures process. This history between stakeholders and stakeholder groups is also thought to have impacted the development of advice ties. Lastly, the transition of the advice network structure over time supports arguments in the literature that suggest that different network structures are necessary at certain time points during participatory processes. Stakeholder group silos also persisted within the communication network. These silos are thought to have helped stakeholder groups develop their own attitude towards scientific models based on their unique “way of knowing”. As a result, attitudes towards models were significantly different between stakeholder groups. This strength of stakeholder group impact on attitudes likely limited overall changes in attitudes towards models over the course of OysterFutures. The importance of considering social network structure of participatory modeling processes was demonstrated through results that certain brokering network positions significantly impacted attitudes towards models. Methods to facilitate more between group communications during participatory modeling processes could help mitigate the strong impact of stakeholder group membership on attitudes. Overall, results for attitudes towards models support the idea that models are acting as “boundary objects” that help facilitate discussion during these processes.

Thousands of floating objects, known as drifting fish aggregating devices (dFADs), are released every year by commercial tropical tuna purse seine vessels in the three equatorial oceans to aggregate tuna and increase catch. The escalation in the number of dFADs deployed over the last three decades has caused changes in fishing effort that are poorly reflected in traditional indices of purse seine effort and catch per unit of effort (CPUE). In addition, concerns have been raised regarding the impacts of such high numbers of dFADs being deployed on both catch and bycatch species. I studied two aspects of dFAD deployments in order to clarify how dFADs are used by purse seiners and how they affect the magnitude of bycatch. My specific goals were to determine how often purse seine vessels fish on the dFADs they deploy and how regional dFAD density affects the magnitude of bycatch and catch. I analyzed commercial data, independent observer data, satellite buoy trajectories, and estimated floating object densities from the French tropical tuna purse seine fisheries in the Atlantic and Indian Oceans to examine these relationships. My results indicate that only 2.7-20.6% of dFAD fishing sets were on the dFADs that French purse seiners deployed over the period 2007-2013. Although this percentage increased over time, such a low percentage suggests that French vessels do not primarily increase CPUE by using the dFADs they deploy for directed fishing. If French purse seiners are not mainly using their own dFADs in this manner, then using a metric of nominal effort based on individual vessel activity is unlikely to produce reliable CPUE estimates for the fishery. While information about how often purse seiners fish on their own dFADs could be incorporated into indices of fishing effort, it may be just as important, if not more so, to quantify the collective component of dFAD releases for overall fishing effort. The results for the second objective showed that average dFAD density had a relatively weak relationship with total bycatch biomass. There was no statistically significant effect on mean total bycatch biomass, but dFAD density was related to heteroscedasticity in bycatch biomass. In particular, there was a significant negative relationship between dFAD density and the upper quantiles of the bycatch biomass distribution, suggesting that dFAD density determines the upper bound for bycatch biomass caught per set. These relationships were not constant across species, however, as the five most prevalent bycatch species (i.e., those caught in the greatest number of sets) showed a mix of positive, negative, or no relationships to dFAD density. The total biomass of catch increased significantly as average dFAD density increased both at the mean and throughout the majority of the distribution, although this effect only explained a small fraction of the total variance in catch biomass. at this time, the low amount of variance explained and the inconsistent impact of average dFAD density on bycatch and target species indicate that it would be ineffective to mitigate bycatch levels in these fisheries by attempting to control regional dFAD densities.

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