Microbial Contamination Survey of Environmental Fresh and Saltwater Resources of Upolu Island, Samoa

Abstract

Analysis of microbe diversity in freshwater resources and nearshore seawater samples of Upolu Island was performed to investigate the distribution of harmful bacteria. For this, 124 samples were collected from 23 river systems, two volcanic lakes, and 45 locations inside and outside the barrier reef of Upolu Island, Samoa. Physicochemical parameters for general water quality, detection of coliform bacteria and 16S rRNA amplicon sequencing were performed on all samples. Fecal indicator bacteria (FIB) testing indicated a wide distribution of coliform bacteria in all sampled freshwater sites with evidence of fecal coliform in most locations. Importantly, evidence of coliform bacteria was found in most seawater samples inside and along the reef, apart from those samples taken ~20 km offshore. Illumina 16S rRNA amplicon sequencing of the V4 hypervariable region confirmed the presence of various types of harmful bacterial species, namely from the Enterobacteriaceae, Enterococcae, Streptococcaceae, and Vibrionacea families. By combining the sensitivity of FIB testing and next-generation sequencing, we were able to show the extent of potential contaminations in fresh and seawater samples and simultaneously identify the potential pathogenic bacterial genera present. The wide distribution of potential harmful bacteria from river runoff or direct sewage dumping has an impact on human health, leading to many skin and intestinal diseases, and is potentially detrimental to coral reef community health.

Heavy Metal Estimation and Quality Assurance Parameters for Water Resources in the Northern Region of Pakistan

“…A recent study that was carried out in Samoa (Upolu Island) showed the presence of many bacterial species, e.g., coliforms, etc. contaminating the water sources [52]. Another study on total coliforms and fecal coliforms was conducted in Mexico and showed the adverse effects on human communities [53].…”

Oyster Reefs Are Reservoirs for Potential Pathogens in a Highly Disturbed Subtropical Estuary

“…Estuarine water quality and benthic conditions are deteriorating worldwide because of urbanization and climate change [1,2]. Of particular concern are increases in the detection of pathogens in estuary waters and sediments that threaten human and ecosystem health [3][4][5][6][7]. These increases are likely due, in part, to improved detection methods.…”

Monitoring and Management of Inland Waters

“…It includes six studies carried out in different countries around the world, which focus on different aspects related to the monitoring and management of inland waters. Specifically, Ochsenkühn et al [1] investigated the presence and distribution of harmful bacteria in river, lake, and nearshore sea-water samples of Upolu Island (Samoa) by combining the sensitivity of fecal indicator bacteria testing and next-generation sequencing. A thorough genetic screening of the broodstocks used for the reintroduction of beluga sturgeon (Huso huso L.) in the Po River basin (Italy) was performed by Antognazza et al [2] to assess the success of a captive breeding program.…”

“…The results presented in this Special Issue should be taken into account for improving both the monitoring and management of freshwater resources: (i) the wide distribution of potential harmful bacteria from river runoff or direct sewage dumping has an impact on human health that should be urgently reduced [1], (ii) a critical requirement for the success of programs for the reintroduction of locally extinct species is the knowledge of the genetic diversity of the selected broodstocks to ensure self-sustainability of the reintroduced populations [2], (iii) taxon richness of benthic macroinvertebrates could be used as a surrogate indicator to assess the water quality when consolidate biomonitoring methods are not available [3], (iv) the presence of endangered diatomic species of particular conservational interest in temporary basins affected by extended drought periods triggers the need for conservation strategies for vulnerable and unstable environments strongly threatened by climate changes [4], (v) long-term monitoring of ecosystem metabolism is required to assess alterations in the function of streams affected by hydrological and temperature alterations exacerbated by the climate change [5], (vi) common operative tools should be implemented for ecological flow assessment in order to make water resource management more sustainable [6], (vii) organic farming and biocontrol could be an alternative to diffuse pollution by agrochemicals, while environmental flows and controlled sediment flushing operations could limit the hydropower impact on rivers [8]. Moreover, the review by Salmaso et al [7] could support the proper design of monitoring plans aimed at assessing the ecological impacts of hydropeaking and the effects of possible mitigation strategies.…”