Spatiotemporal water dynamics effects on plant functional types in a tropical urban coastal wetland: water sources and quality in the Ciénaga Las Cucharillas, northeastern Puerto Rico.
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Autor
Pinto-Pacheco, Solimar
Advisor
Cuevas, ElviraMedina, Ernesto
Tipo
DissertationDegree Level
Ph.D.Fecha
2023-12-22Metadatos
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Coastal wetlands have complex hydrologies influenced by multiple water sources such as in-situ precipitation, superficial and subsurface inputs from rivers and channels, as well as sea water. Each source provides ionic inputs into the system that can be used to establish an elemental profile and the relative importance of the water sources in the spatio-temporal dynamics of the system. The objective of this dissertation was to determine the spatio-temporal dynamics of the water sources, the ionic elemental inputs, and the relative proportions of the sources water sources available to plants in a tropical coastal urban wetland. This objective is centered on Ciénaga Las Cucharillas, an urban-coastal wetland in the Cucharillas microbasin, located on the western side of the San Juan Bay Estuary, Puerto Rico. To address the objective, three main aims were proposed. Aim 1 identified the differential sources of water inputs in the wetland using the natural abundance of stable isotopes of water δD and δ18O). Aim 2 determined the relative contribution of the water sources to the plants using the natural abundance of δ18O and δD. Samples were collected from representative species of functional plant types: woody plants (halophytic tree Laguncularia racemosa (L.) C.F. Gaertn, and, non-halophyitic shrub Dalbergia ecastaphyllum (L.) Taub), and herbaceous plants (the fern Acrostichum danaeifolium Lagnsd. & Fisch, and the grass Panicum cf. laxum Sw.) were sampled. Lastly, Aim 3 determined changes in elemental inputs of the water sources as hydrology of the wetland is affected by basin-wide anthropogenic activities as well as by deep subsurface saline intrusion and tidal effects. In general, weather variability dictated spatio-temporal distribution of water inputs (in-situ precipitation, water from the Malaria Channel and seawater) as well as influenced ionic concentrations. Relative contributions of the water sources also varied among plant species in response to environmental constraints that the species are exposed to. Global climate change and anthropogenic activities stressors to the system. Understanding the water dynamics of the wetland and its effects on plant community dynamics makes this project relevant for determining how the relative changes in freshwater source and saline intrusion will affect coastal wetland dynamics.