The United States’ Endangered Species Act of 1973 has been recognized as one of the most powerful laws enacted to protect endangered species in the world. Its protections for animal species extends onto private land, which has in some cases created conflict between the law, its enforcers, and private landowners. The Candidate Conservation Agreements with Assurances (CCAA) program was developed in 1999 to provide a regulatory incentive for private landowners to engage in pro-active conservation for sensitive species to preclude the need for listing under the ESA in the future. Since 1999, however, there have only been 17 CCAAs signed, a relatively small number given the thousands of species eligible for the program across the U.S. This research used semi-structured qualitative interviews with individuals from four participant categories to expand our understanding of why landowners might choose to participate in the CCAA program, and of what benefits and barriers they perceive in program implementation. Participant categories included 1) private landowners enrolled in a CCAA; 2) private landowners that are eligible to enroll, but declined to participate; 3) State fish and wildlife agency employees who have participated in CCAAs across the county; and 4) Fish and Wildlife Service employees responsible for CCAA program implementation. Twenty-six interviews were completed during this research project. Results suggest that program implementation is affected by a multitude of factors; no exclusive drivers were identified. However, the variety of factors that were identified are assessed and management and policy recommendations are made. Hopefully these results and recommendations can potentially affect program policy to increase participation and the potential of the CCAA program as an effective tool for conservation on private lands in the United States.

Approximately 48% of Americans use prescription drugs within each 30-day period, and there are signs this trend is increasing. Although many studies track pharmaceuticals’ fates in contaminating waterways, only fairly recent efforts have examined the potential impacts of these drugs on non-target organisms. The antibiotics sulfamethoxazole and trimethoprim, often prescribed together to treat bacterial infections, have been detected worldwide in marine and estuarine environments at concentrations up to 700-800 ng/L each. Toxic effects of these drugs have been identified in freshwater organisms, with synergistic effects observed in short-term studies of mixtures of the two; however, little research has examined possible sub-lethal and longer-term effects of antibiotics in environmentally-relevant mixture concentrations on marine organisms. I examined the long-term effects of mixtures of these two antibiotics in species of a marine system: marine microalgal species, and marine mussels, to determine whether the levels currently present in waterways affect organism health and reproduction. Microalgal species may be among the most sensitive organisms to pharmaceutical contaminants based on ecotoxicity research. I exposed three species of marine microalgae (Isochrysis galbana, Chaetoceros neogracile, and Nannochloropsis oculata) to environmentally-relevant mixtures of sulfamethoxazole and trimethoprim and examined their three-week growth rates. I found that for each species, the antibiotic treatments significantly suppressed algal growth. Specifically, I found that sulfamethoxazole was a driving factor in suppression of C. neogracile and I. galbana growth, while N. oculata responded more sensitively to a broader range of treatment mixture levels, which also included trimethoprim-only treatment groups and mixtures. These results on marine microalgae address critical data gaps, and identify the impacts of pharmaceuticals on marine primary producers, which could have direct ecosystem implications to higher trophic levels. Antibiotic pharmaceuticals can also affect marine mussel health, based on previous study of sub-cellular endpoints. I hypothesized that the important benthic foundational species, the Mytilus californianus mussel, would be significantly impacted by long-term 12-week exposure to environmentally-relevant concentrations and mixtures of sulfamethoxazole and trimethoprim. Specifically, I measured growth rate, feeding rate, condition index, and gonando-somatic index as indicators of whole-organism and reproductive health. Sulfamethoxazole concentrations, in particular, and trimethoprim to a lesser extent, suppressed mussel growth and significantly affected condition index and gonandosomatic index over time. The results of this study offer an understanding of how an intertidal system responds to chronic presence of antibiotic mixtures in the water, and a more complete picture of the environmental consequences of pharmaceutical contaminants released into marine ecosystems at ever-growing rates.

Antelope Valley is situated in Southern California and is bounded by the Tehachapi and the San Gabriel Mountains. It stretches over 2,200 mi2 and encompasses Rosamond Dry Lake and the 1,200 mi2 watershed draining into it. The cities of Lancaster and Palmdale are the two major urban centers that lie in the watershed draining into Rosamond Dry Lake. The lake lies within the vicinity of the Edwards Air Force Base and provides an important site for aviation research and test operations in addition to ecosystem services. Hence, it is necessary to balance the need to remove water from the lake to support Edwards Air Force Base’s aircraft missions and the need to inundate the lake to protect the its surface and the ecosystem it supports. In this study, satellite-based elevation, state of the science land cover and soil data are used to create a model that predicts storm runoff volume into Rosamond Dry Lake. Geographical Information Systems software is used delineate and divide the watershed into 98 sub-basins. Each sub-basin is assigned a land cover type, percent impervious area, and hydrologic soil type to calculate the Natural Resource Conservation Service curve number. The model also incorporates two detention basins to represent existing flood control structures in Lancaster and Palmdale. Runoff in each subbasin is estimated using the Natural Resource Conservation Service Curve Number method and accumulated into the channels. In a hydraulic modeling software developed by the Army Corps of Engineers, the modeling system is applied to calculate the total storm runoff volume into Rosamond Dry Lake for ten historical storm events as well as a 100-year event. Due to the lack of stream gauge data, a technique that couples Landsat 7 satellite images of Rosamond Lake with LIDAR elevation data to estimate observed runoff volume is developed to evaluate model performance. In comparison to these estimates, the model overestimates runoff volume by approximately 7%. However, there are considerable biases for two storm events that are caused by the effects of evaporation, wind and snow on the lake’s water and various deficiencies in the model. The impacts of past and future urbanization on the runoff volume into the lake are examined by modifying the curve number in sub-basins representative of the urban centers. For a 100-year, 24-hour, precipitation event, urbanization results in increased runoff at both the sub-basin and watershed levels. Additional simulations indicate that measures such as building detention basins and repurposing unused or undeveloped areas within an otherwise developed area (infill) can mitigate increased runoff due to urbanization. Overall, the model proves to be an effective tool for predicting runoff into Rosamond Dry Lake. It can also be used to study the rainfall-runoff processes in the lake. The ability to predict water volumes in the lake will allow engineers and planners to establish a balance between the Air Force Base’s aircraft missions and the lake’s ecological function. Lastly, the techniques used to develop the model can be used to develop similar models for other watersheds. iii

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The coastal landscape is a naturally shifting mosaic of distinct ecosystems that are rapidly migrating with climate change. While directional changes in climate, such as warming and sea level rise, are fundamentally reorganizing the coastal landscape, ecosystem function, especially carbon storage, is affected to an unknown degree. This dissertation presents four chapters that examine the role of ecosystem transitions in coastal carbon dynamics across a range of spatial scales – within individual ecosystems, between two ecosystems, and at the landscape between an array of ecosystems. Ghost forests, or the marsh-forest ecotone, serves as an ideal example of a migratory ecotone. As sea levels rise, terrestrial forests die-off from salt water intrusion and are replaced by salt-tolerant marsh species. While this transition is widely seen and studied, we present the first field study that quantifies carbon loss during this transition (Chapter 1). Significantly, we find that the loss of carbon during marsh migration can be replaced by the accumulating marsh soils, but the timescale for this replacement is at the scale of centuries. Warming, a co-occurring climate stressor, is expected to affect carbon storage to an unknown degree as it affects both antagonistic properties to soil carbon storage: production and decomposition. In a whole-ecosystem soil warming experiment, we find that moderate amounts of warming consistently maximized root growth, marsh elevation gain, and belowground carbon accumulation (Chapter 2). However, our work indicates nonpermanent benefits as global temperatures continue to rise and elevated temperatures exacerbate marsh elevation and carbon loss. At the landscape scale, we see that while climate change can drastically reduce or increase the extent of coastal habitats, compensatory mechanisms largely maintain individual ecosystem extents (Chapter 3). However, coastal squeeze in some environments still reduce extents of ecosystem critical to regional carbon storage. Blue carbon habitats that comprise the coastal zone are able to compensate this loss in less time than it takes to accrue that loss. These findings reveal unique functional compensatory mechanisms at the landscape scale that quickly absorb carbon losses and could facilitate increased regional carbon storage in the face of accelerating climate change. Finally, we concentrate on ecosystem vulnerability of salt marshes, an ecosystem with a critical role in global and local carbon dynamics. By leveraging decadal SET data, we are able to identify early warning signals of marsh collapse in the changing microtopography of the marsh surface (Chapter 4). Increasing microtopographic heterogeneity in degrading salt marshes mirrored trends in a diverse array of systems with alternative stable states – indicating that early warning signals of marsh drowning and ecosystem transition are observable at small-spatial scales prior to runaway ecosystem degradation. Congruence between traditional and novel metrics of marsh vulnerability indicate that microtopographic metrics can be easily applied to existing SET records to identify hidden vulnerability before widespread marsh degradation.