Citation:

Cappielo Cosme, I., S. Eytcheson, E. Villafane Deyack, A. Oczkowski, Alana Hanson, M. Schwartz, D. Katz, E. Huertas, AND M. Molina. Relationships among microbial source tracking (MST) markers, traditional fecal indicator bacteria and environmental parameters in a tropical urban estuary. Health and Climate Summit 2022, St. Thomas, PR, June 06 - 10, 2022.

Impact/Purpose:

The objective of this study was to assess sources of fecal contamination at the San Juan Bay Estuary (SJBE) and identify “hot spots” areas for sewage contamination, examine relationships among MST marker concentrations, water quality parameters, and FIB concentrations  in a tropical urban estuary.  The information from this research project will provide information to support mitigation and remediation efforts to manage pollution sources.  

Description:

Assessing the level of risk associated with inputs of fecal contamination in estuarine environments is an important step to develop coastal management plans that are protective of human health and the environment. In this study, we assessed sources of fecal contamination and the relationships among microbial source tracking markers (MST), pathogenic genes, and traditional fecal indicator bacteria in a tropical estuarine system, the San Juan Bay Estuary (SJBE).  SJBE consists of five lagoons interconnected by channels and limited exchange with open coastal ecosystems. Sixteen locations were sampled every other week for 12 months in a combination of boat and land grab samples. Quantitative polymerase chain reaction (qPCR) assays were conducted to determine the presence of human, avian, pig, and dog markers along with culturable enterococci, and qPCR enterocci and E. coli assays. Sequencing of 16SRNA genes was also conducted to determine presence of waterborne pathogens. Our results indicate that          human contamination is prevalent in the SJBE with gene copy (GC) numbers ranging from 103 to 105 per 100 ml. The highest concentrations of human fecal marker were identified at the Caño Martín Peña (CMP) which is one of the main channels surrounded by communities lacking proper sanitary sewer or stormwater infrastructure.  When the human marker was>105, the markers for dog and pig were also identified at CMP. This trend correlated with lower salinity and higher precipitation events, suggesting both a breach in the sanitary system and an effect from stormwater runoff.  Molecular data will be combined with physicochemical and meteorological parameters to develop predictive models to identify relationships with fecal indicator bacteria and potential presence of pathogens.  Our study provides information about the level of anthropogenic impacts on tropical estuaries and identifies conditions that increase ecosystem degradation and human health risks.   

Record Details: