From Human Threats to Human Solutions: Impacts of Freshwater Runoff Pollution on Rocky Shores and a New Approach to Training Environmental Problem Solvers

The magnitude and scale of current threats to ecosystems requires interdisciplinary approaches to both science and training. For example, urbanization has resulted in increased runoff from communities into coastal habitats, necessitating work across the marine-terrestrial interface. This runoff holds myriad pollutants which can impact vulnerable ecosystems, such as coastal rocky reefs. I evaluated two pollutants in domestic runoff, nitrogen-based nutrients and glyphosate-based herbicides, and their effects on rocky intertidal biodiversity and ecosystem health. Biweekly measurements were taken from runoff-affected tidepools, runoff-unaffected tidepools, drain sources, and the ocean to assess levels of both nutrients and glyphosate at our Southern California field site. Further, I experimentally added nutrients to tidepools and dosed the green seaweed "Ulva" sp. with glyphosate to determine the extent of effect these pollutants would exert on the ecosystem. In chapter 1, I showed that nitrate + nitrite concentrations varied over time, with runoff-affected tidepools exhibiting significantly higher concentrations than control tidepools. Internal nitrogen concentrations in "Ulva" correlated positively with nitrate + nitrite concentrations, and total grazer biomass increased with higher internal nitrogen in "Ulva." Experimental nitrogen additions enhanced "Ulva" cover compared to control pools. In chapter 2, I showed elevated glyphosate concentrations exceeding EPA safe drinking-water limits in the field, with substantial pH reductions observed at low glyphosate concentrations. These findings indicate that increased nutrients lead to bottom-up effects on nutrient cycling, and that reduction in pH associated with glyphosate has the potential for appreciable reduction in local pH. My findings underscore the need for regulatory consideration of these pollutants in coastal management, especially in protected areas, to mitigate risks to marine ecosystems and human health. However, environmental challenges, such as polluted freshwater runoff, are global in both scope and scale. Interdisciplinary and collaborative approaches to research can be used to better address these complex issues, and in chapter 3, I describe a graduate training program that centers these approaches. The Ridge 2 Reef National Science Foundation Research Traineeship Program was developed to provide transferable and cross-disciplinary training to graduate students of various academic backgrounds. The program was successful in improving the communication skills, career knowledge, and understanding of global perspectives in research of the trainees. The interdisciplinary and collaborative approaches to training were also successful in increasing trainee confidence and preparedness for environmental career paths. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]