This dissertation enhancement proposal, will support the dissertation research of Mr. Michael Beman under the supervision of Dr. Pamela A. Matson of Stanford University, and in collaboration with Dr.Esther Cruz at the Centro de Conservacion para el Aprovechamiento de los Recursos Naturales (CECARENA) of the Instituto Tecnologico de Estudios Superiores de Monterrey (ITESM). The proposed research will study the effects of agricultural runoff from the Yaqui Valley of Mexico on the coastal systems in the Gulf of California.
Agricultural runoff can have large-scale influences on phytoplankton biomass in the open waters of the Gulf. Based primarily on data from satellite remote sensing, it is argued that coastal upwelling of nutrients, augmented by agriculturally-derived nutrients, results in large phytoplankton blooms and plumes that can reach almost 50 km in scale. These results further imply that the estuaries of the Yaqui Valley are sites of important and possibly quite unique biogeochemical transformations. The proposed research is focused on a smaller spatial scale, and aimed at understanding microbial community structure and function in one of these estuaries, Bahia del Tobari. The work will employ a combination of genetic techniques, sediment manipulations, and in situ biogeochemical measurements to understand nitrogen transformations and losses from Tobari, and how these processes are linked with processes at work in the Gulf. As a highly connected land-sea system undergoing rapid change, the Yaqui Valley-Gulf of California represents a model system for understanding the acceleration of coastal change worldwide.
