Microbiological Contaminants in Recreational Waters of the San Juan Bay Estuary
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Water
Session: 4
Room: Gallery Place
Mariana Nicole García-Díaz - University of the Sacred Heart
Co-Author(s): Noemi Soto-Nieves, University of the Sacred Heart, San Juan, PR; Ivelisse Cappielo-Cosme, ORISE at EPA, San Juan, PR.
The San Juan Bay Estuary is a network of lagoons, rivers, and channels along the north coast of Puerto Rico. It encompasses various ecosystems before flowing into the Atlantic Ocean. Socioeconomical factors such as the industrialization of the 1930s, forced many Puerto Ricans to establish themselves surrounding the Martin Peña Channel within the Estuary. The rapid increase in population resulted in unregulated constructions that blocked the Channel, hindering water flow. This has led to floodings in the nearby communities during raining events, and to make matters worse, the poor or nonexistent sewage systems have heavily contaminated said waters.Our investigation aims to determine the water quality and microbiological contamination of the San Juan Bay Estuary. In collaboration with the U.S. Environmental Protection Agency (EPA), we have been collecting monthly water samples for three years in five strategic stations along the Estuary, specifically in the blocked areas of the Martin Peña Channel and its surrounding water bodies. Each month, we used a YSI to measure the water’s physical and chemical parameters such as temperature, pressure, pH, salinity, and oxygenation. The water’s turbidity was tested employing a Turbidity Meter; and Total Fecal Coliforms, Escherichia coli, and Enterobacteria were determined according to the IDEXX Quanti-Tray System’s Colilert and Enterolert assays. These assays provide the number bacteria (CFU/mL) in the water based on the Most Probable Number (MPN) Table after 24-hour incubation at 44.5 ⁰C and 41.0 ⁰C respectively.The physical and chemical parameters showed expected results, such as the inversely proportional correlation between temperature and oxygenation. Currently, we are taking into consideration factors such as rain or drought events to correlate with the number of bacteria. Data analysis shows that the five stations monitored exceed EPA recreational water parameters, which establish a maximum of 35 CFU/mL for Enterococci and 200 CFU/mL for Total Fecal Coliforms and E. coli. In the Martín Peña Channel especially, contamination surpassed these regulations by an average of 95.5x, 66.0x, and 46.0x respectively. This poses a public health risk and security hazard for the 26,000 residents whose homes surround the channel and are directly exposed to the water during floodings. Our data justifies the community petition for the channel’s dredging, which after 40 years’ effort, was finally approved in January 2023. Fortunately, we have an unprecedented opportunity to compare data for the preservation of the San Juan Bay Estuary before, during, and after the Martín Peña Channel’s scheduled dredging. In the future, we aim to include DNA isolation assays such as RT-PCR to identify pathogens in the water and possible links to current health issues within the communities.
Funder Acknowledgement(s): This investigation is supported, in part, by Sagrado IUSE HSI Project – NSF Proposal number 1928543; Project CoRA-S - U.S. Department of Education under federal grant #P031C210100; and USEPA equipment loans.
Faculty Advisor: Noemi Soto-Nieves, Ph.D., noemi.soto@sagrado.edu
Role: Since joining the project, I have been involved in all aspects of the research, from field to laboratory work. I have collaborated in the preparation of necessary equipment, station water sampling, and YSI data collection, as well as performing the Enterolert and Colilert assays. I oversee reading the assays mentioned and am responsible for logging and uploading our data. Currently, I am learning to analyze data statistically in different programs such as R and Microsoft Excel.