This body of work examines the influence of land use on nearshore water quality, and how this can drive changes to algal and invertebrate communities along Australia's southern coastline. The overall aim of the thesis was to investigate links between increasing coastal water-column nitrogen concentrations (derived from terrestrial inputs) and the expansion of turf-forming habitats that can alter the structure and function of subtidal ecosystems. I initially tested whether human activities in coastal catchments can increase subsidies of nitrogen to open rocky coasts. I identified landscape-scale variation in the supply of Dissolved Inorganic Nitrogen (DIN) to coastal waters adjacent to natural, agricultural and urban catchments. Compared to natural catchments, subsidies of DIN were 8 - 407 times greater in urban catchments, and 1 - 63 times greater in agricultural catchments. Subsidies of nitrogen from urban catchments were attributed to the release of sewage effluent, as delineated by δ¹ ⁵N isotopic values of transplanted algae. Having made this link, I then assessed whether catchment-scale variation in nitrogen subsidies may predict patterns of subtidal habitat structure, particularly as related to theories of regime shifts from forested landscapes to structurally depauperate turf-forming habitats. I validated this hypothesis, demonstrating that both relative covers and patch-sizes of turfed habitat were greater where the ratio of terrestrial nitrogen inputs to ambient coastal resources was large. An important realisation was that loss of forests may be more strongly related to the size of subsidy (i.e. the relative increases in water column nitrogen concentrations along urban coasts) rather than the size of coastal populations. Together, these data link coastal development with modified land-to-sea subsidies, and indirectly support the model that ecological effects may be proportional to the disparity between donor and recipient resources. Having demonstrated a link between nitrogen subsidies and subtidal habitat change, I then investigated factors likely to initiate and maintain such shifts. My results demonstrate that nutrient elevation can alter the natural phenology of turfs, sustaining dense covers throughout periods of natural senescence (winter). Perennial turf covers are able to accumulate large volumes of sediment; a synergy can impede the winter recruitment of canopy-forming species (kelps and fucoid algae). My observations of reduced forest recovery along urban coasts serve to highlight the complex interaction between elevated nutrients, persistent turf covers and increased sediment accumulation, which can reduce the resilience of coastal ecosystems to disturbance. In recognition that regime shifts are likely to have consequences for higher trophic levels, I compared the diet of invertebrate herbivores from healthy and degraded coastlines using stable isotope analysis (δ¹³C and δ¹⁵N). Dietary modelling showed that turfs contributed more to the diet of consumers along degraded coastlines where turfed landscapes have replaced extensive covers of macroalgal forest. Additionally, there were strong correlations between covers of turfed habitat, herbivore diet and relative densities. Changes to ambient food quality associated with regime shift may be an important aspect of nutrient-driven change along human-dominated coastlines. The final component of my thesis redressed some of the uncertainty about restoration initiatives for urban coasts by demonstrating that regime shifts are not necessarily permanent. I showed that turf removal can facilitate the recovery of degraded forests. Future restoration, therefore, is a possible outcome of polices that aim to decouple the link between nutrient inputs and recalcitrant turfed habitats that prevent forest recovery. Initiatives that reduce nutrient discharge to coastal waters (e.g., wastewater recycling) are likely to restore the resilience of nearshore marine ecosystems and promote their rehabilitation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1473469 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

This body of work examines the influence of land use on nearshore water quality, and how this can drive changes to algal and invertebrate communities along Australia's southern coastline. The overall aim of the thesis was to investigate links between increasing coastal water-column nitrogen concentrations (derived from terrestrial inputs) and the expansion of turf-forming habitats that can alter the structure and function of subtidal ecosystems. I initially tested whether human activities in coastal catchments can increase subsidies of nitrogen to open rocky coasts. I identified landscape-scale variation in the supply of Dissolved Inorganic Nitrogen (DIN) to coastal waters adjacent to natural, agricultural and urban catchments. Compared to natural catchments, subsidies of DIN were 8 - 407 times greater in urban catchments, and 1 - 63 times greater in agricultural catchments. Subsidies of nitrogen from urban catchments were attributed to the release of sewage effluent, as delineated by δ¹ ⁵N isotopic values of transplanted algae. Having made this link, I then assessed whether catchment-scale variation in nitrogen subsidies may predict patterns of subtidal habitat structure, particularly as related to theories of regime shifts from forested landscapes to structurally depauperate turf-forming habitats. I validated this hypothesis, demonstrating that both relative covers and patch-sizes of turfed habitat were greater where the ratio of terrestrial nitrogen inputs to ambient coastal resources was large. An important realisation was that loss of forests may be more strongly related to the size of subsidy (i.e. the relative increases in water column nitrogen concentrations along urban coasts) rather than the size of coastal populations. Together, these data link coastal development with modified land-to-sea subsidies, and indirectly support the model that ecological effects may be proportional to the disparity between donor and recipient resources. Having demonstrated a link between nitrogen subsidies and subtidal habitat change, I then investigated factors likely to initiate and maintain such shifts. My results demonstrate that nutrient elevation can alter the natural phenology of turfs, sustaining dense covers throughout periods of natural senescence (winter). Perennial turf covers are able to accumulate large volumes of sediment; a synergy can impede the winter recruitment of canopy-forming species (kelps and fucoid algae). My observations of reduced forest recovery along urban coasts serve to highlight the complex interaction between elevated nutrients, persistent turf covers and increased sediment accumulation, which can reduce the resilience of coastal ecosystems to disturbance. In recognition that regime shifts are likely to have consequences for higher trophic levels, I compared the diet of invertebrate herbivores from healthy and degraded coastlines using stable isotope analysis (δ¹³C and δ¹⁵N). Dietary modelling showed that turfs contributed more to the diet of consumers along degraded coastlines where turfed landscapes have replaced extensive covers of macroalgal forest. Additionally, there were strong correlations between covers of turfed habitat, herbivore diet and relative densities. Changes to ambient food quality associated with regime shift may be an important aspect of nutrient-driven change along human-dominated coastlines. The final component of my thesis redressed some of the uncertainty about restoration initiatives for urban coasts by demonstrating that regime shifts are not necessarily permanent. I showed that turf removal can facilitate the recovery of degraded forests. Future restoration, therefore, is a possible outcome of polices that aim to decouple the link between nutrient inputs and recalcitrant turfed habitats that prevent forest recovery. Initiatives that reduce nutrient discharge to coastal waters (e.g., wastewater recycling) are likely to restore the resilience of nearshore marine ecosystems and promote their rehabilitation. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1473469 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2009

Doctor of Philosophy(PhD) / This thesis uses a political ecology framework to critically analyse how development and environmental orthodoxies influence the use, management and development of living aquatic resources in an information poor developing country context. The research focuses specifically on Lao PDR, the only landlocked country of the Mekong River Basin, to question how knowledge over living aquatic resources is framed by a range of stakeholders. Specific attention is given to how aquaculture has gained ascendancy over capture fisheries in the rhetoric of resources users as well as government and nongovernment organisations. The empirical research focuses on the role of broad scale economic, social and environmental influences over resource use, the practical and perceived importance of both aquaculture and capture fisheries in rural Lao livelihoods and finally, how living aquatic resources are represented within the dominant development agendas of conservation, poverty alleviation and rural development. Field work was conducted in Savannakhet province in Southern Lao PDR over 18 months from 2001 to 2002. The thesis has a strong empirical research base divided into activities carried out over multiple scales ranging from household to the Mekong River Basin. The thesis begins by establishing the historical context of resource use as well as the major orthodoxies on which development is based. Attention then turns to the extensive empirical research conducted over three districts of Savannakhet province. The results of the empirical research report two macro scale studies at the district level. The first is a survey of fish ponds across three districts focusing on the spatial distribution of investment and resource use. The second is a survey of fish trade focusing on the differential trade between culture and capture fish species. The results of both studies highlight the disjuncture between complex patterns of aquaculture and capture fishery use and the major assumptions made about the use of these two resources by policy makers and management. Analysis then moves to the local level focusing on the role and importance of aquaculture and capture fisheries to the livelihoods of rural Lao communities. The results show the instrumental and hermeneutic importance of fish and other aquatic resources in the livelihoods of households and the community. In particular it is shown that capture fisheries are more important to rural livelihoods in terms of income and nutrition, while aquaculture is perceived as a more important activity in the development of community and household economies. ii The final section then compares the empirical findings of the thesis with the policy and planning agendas of government and non-government organisations. The analysis focuses on the role of ideas and agency creating a highly politicised policy environment concluding that aquaculture based policy is more compatible with both government and non government agendas of poverty alleviation and rural development than capture fisheries. Furthermore, capture fisheries are marginalised within conservation as a resource that cannot contribute to the improvement of livelihoods or alleviate poverty. The thesis concludes that living aquatic resources provide an imperative source of food and income to rural communities through diverse and complex human-environment interactions. In contrast government and non-government organisations operating at regional, national and local scales of policy and planning simplify these relationships drawing on wider orthodoxies of aquaculture and capture fisheries development. These simplifications do not reflect the problems and needs of the predominantly rural population. Furthermore, in the absence of a strong empirical base of information, living aquatic resources management and development has become highly politicised. Instead of responding to the realities of resource users, policy and planning reflect the interests and beliefs of development organisations, government and non-government. The thesis provides an important, grounded account of the importance of living aquatic resources to rural livelihoods in Lao PDR and how these resources are understood and translated into national development and management agendas. In doing so the thesis contributes to an understanding of how complex human-environmental systems are perceived and represented in development policy and wider knowledge systems. The thesis also makes an important theoretical contribution to the growing body of literature on critical political ecology by arguing for the revitalisation of ecology as an integrated approach within political ecology and more widely within the study of humanenvironment interaction.

Due to the complex nature of aquatic food webs, the interaction between abiotic and biotic factors that govern ecosystem dynamics is often elusive. Recent advancements in both the collection of reliable field data and the development of ecological models have enabled researchers to gain insights into these more complex interactions. In this study the relationship between physical and ecological processes has been explored by applying a process based coupled physical and ecological model (DYRESM-CAEDYM) to the data sets of three aquatic ecosystems. In the first, the role of zooplankton in the nutrient cycles of Lake Kinneret, Israel was quantified. The model was parameterized and calibrated using an extensive field data set. It was found that the excretion of dissolved nutrients by zooplankton accounted for up to 58% of phytoplankton demand and that this value varied seasonally in response to patterns of stratification and mixing. In the second ecosystem, Mono Lake, USA, results from model simulations were studied to determine the significance of the transport of nutrient rich hypolimnetic water via the benthic boundary layer (BBL) on lake productivity. Model results indicated that although on average the impact of BBL transport on Mono Lake ecology was not large, significant nutrient fluxes were simulated during periods when BBL transport was most active. The timing of these fluxes in the context of seasonal changes were found to be critical to specific aspects of food web dynamics. In the final application, the ecological gradients of the primary salt ponds of Shark Bay, Australia were studied with specific focus on the role of zooplankton as a determinant of ecosystem dynamics. Model results indicated that zooplankton grazing was responsible for reduced water column particulate organic matter and increased light available for the development of microbial mats. However, no direct 8 link between zooplankton grazing and observed changes in planktonic algal species composition or nutrient limitation across the salinity gradient of the ponds was found. Results from this study demonstrate the potential of a lake ecosystem model to extract useful process information to complement field data collection and address questions related to the relationship between physical and ecological processes in aquatic ecosystems.

Thesis (Ph.D.)--University of Western Australia, 2006.

Diss. (sammanfattning) Uppsala : universitet, 2006. / Härtill 6 uppsatser.

Thesis (M.S.)--University of North Texas, August, 2008. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Biological Sciences, 2006. / Title from Web page (viewed on Sept. 16, 2008). Includes bibliographical references (p. [30-35]).

Thesis (M. Ed.)--Kutztown University of Pennsylvania, 1990. / Source: Masters Abstracts International, Volume: 45-06, page: 3051. Typescript. Includes bibliographical references (leaves 42-46).

Thesis (Honors)--Liberty University Honors Program, 2007. / Includes bibliographical references. Also available through Liberty University's Digital Commons.