Nutrient Dynamics in the Laguna San Jose a Tropical Urban Lagoon in the San Juan Bay Estuary, Puerto Rico
Pérez-Villalona, Hamlet Nelson
Ortiz Zayas, Jorge R. (Consejero)
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Globally, anthropogenic nitrogen inputs to coastal ecosystems are causing eutrophication of estuaries and aquatic habitats degradation, thus affecting their biodiversity and trophic structure. Understanding the biogeochemistry of nitrogen compounds in estuaries might provide valuable information to evaluate the dynamics of anthropogenic nitrogen loadings and to calculate basin-level nitrogen budgets which are needed in the restoration of rivers and estuaries. Historically, the San Juan Bay Estuary of Puerto Rico has been influenced by human activities and despite the removal of some point sources of pollution, today certain sections remain polluted. The magnitude and fate of anthropogenic nitrogen inputs to the San Juan Bay Estuary of Puerto Rico are unknown. Therefore, a study was conducted to assess the nitrogen dynamics in the Laguna San José, one of the main water bodies within the San Juan Bay Estuary of Puerto Rico. The aims of this research were: (i) to define the hydraulic characteristics of the watersheds effluents of the Laguna San José; (ii) to assess the current eutrophication levels in the Laguna San José; (iii) to determine the dissolved inorganic nitrogen, dissolved inorganic phosphorous fluxes and diatomic nitrogen removal by denitrification 2 at the sediment-water interface of the Laguna San José; and (iv) to develop a nitrogen budget for the lagoon. My doctoral dissertation explores the nitrogen dynamics and anthropogenic impact on the Laguna San José (LSJ) and its tributaries, located in the San Juan Bay Estuary in Puerto Rico (SJBE). Given the global concern on the effect of high nitrogen inputs to coastal waters and the harmful effect of eutrophication on these waters (Vitousek et al. 1997; Seitzinger et al. 2006; Howarth 2008), it is necessary to have a complete understanding of the nitrogen cycle and its particularities under highly degraded tropical coastal waters, as is the case in certain parts of the SJBE. This introductory chapter begins by explaining the topics that unify this research, i.e the nitrogen cycle in coastal waters, a review of literature regarding the impact of high nitrogen loads on estuaries, and a description of the study site. Then, it follows with a sketch of each of the chapters of this dissertation. The Chapter 5 consists of general conclusions.