Investigating the Coastal Water Quality of the Galapagos Islands, Ecuador

Abstract

The Galapagos Islands offer a unique ecological landscape found nowhere else in the world. However, a lack of water and sanitation infrastructure within populated areas of the Galapagos Islands has the potential to affect many of these ecosystem attributes. Specifically, a rapidly growing population and expanding impacts of tourism are contaminating the coastal environments of the Galapagos Islands. Water quality monitoring is conducted globally to provide important information on the incidence of dangerous microbial contamination. Fecal indicator bacteria (such as Enterococcus spp. and Escherichia coli) are quantified as proxies for the presence of pathogens that can be found in water that is contaminated with human and animal feces. These fecal indicator bacteria, however, cannot be used to indicate a specific source of fecal contamination. Recently, advancements have been made in the quantification of other alternative markers for human fecal contamination, such as members of the Bacteroidales group. These are bacteria or gene markers in the bacteria that are predominantly found in the human gastrointestinal tract and, as such, can be more accurate indicators of the presence of human fecal pollution. In this study, we used molecular techniques for measurement of DNA to quantify both Enterococcus spp. and Bacteroides spp. specific molecular markers of human fecal contamination in the coastal waters of San Cristobal and Santa Cruz islands. Enterococcus spp. and Bacteroides spp. specific molecular marker concentrations were high enough in certain locations to warrant concern. Human fecal pollution was present in both coastal marine beach waters and a brackish water lagoon popular for bathing and recreation. Since our study, the wastewater treatment plant on San Cristobal has been upgraded, possibly resulting in reduced microbial contamination. However, these results indicate that poor wastewater management could be posing a threat to human health for both residents and tourists, and the coastal environments of the Galapagos Islands. Improvements to marine water quality are critical to protect inhabitants, tourists, and the fragile ecosystem components of the Galapagos Islands and to ensure the long-term viability and sustainability of a unique place.