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Supporting Efficient and Effective Restoration of Surface Waters from Multiple Fecal Pollution Sources in Puerto Rico
Citation:
SantoDomingo, J. Supporting Efficient and Effective Restoration of Surface Waters from Multiple Fecal Pollution Sources in Puerto Rico. Preamble of the 6th Congress on the State of the Environment, NA, PUERTO RICO, August 25, 2022.
Impact/Purpose:
This presentation will focus on the evaluation of molecular assays to detect the presence of fecal bacteria and indicaors of fecal source tracking in tropical waters.
Description:
Microbial water quality is determined by enumerating fecal indicator bacteria (FIB) using culture-based techniques. This conventional approach does not discriminate between the different fecal sources impacting natural systems. Alternatively, microbial source tracking (MST) qPCR assays have recently been used to detect the primary fecal sources impacting surface waters. These assays have been frequently used in temperate countries but their evaluation in tropical waters has been conducted to a much lesser extent. In this study, we used several qPCR assays to assess the levels and sources of fecal bacteria and MST markers during 13 months in a watershed located in Puerto Rico. We tested the specificity of the markers and the spatial-temporal prevalence of these bacterial gene targets in sites impacted with different levels of pollution and fecal sources. Additionally, we studied the bacterial composition of the water samples using 16S rRNA gene sequencing analysis. The results of this study indicate that human and ruminant sources are primarily impacting this watershed. The data also shows that some of the MST assays could cross-react with different hosts suggesting that new markers may be needed for Puerto Rico. There were notable differences in the bacterial community structure associated with rain events. Moreover, differences in fecal bacteria levels were observed during wet and dry season, with indicators of fecal pollution sources showing a better correlation with FIB during wet season. The results highlight the performance of some of most widely use MST genetic targets and are relevant to implementing adequate management practices aiming at reducing fecal pollution loads in the island.