Feces don’t seem to be on the menu for zooplankton. Although these small aquatic animals are known to graze on other bacteria, new research indicates that they do not “clean” fresh or salt water by eating the fecal microorganisms in the contaminated H.20. The findings are detailed in a study published Oct. 3 in the journal Biology Journal mSphere.
Water from sewage and septic tanks can accidentally enter freshwater bodies due to inadequate water treatment. corroded infrastructure, drainage of rainwaterand accidents. This contamination can make people and other animals sick if they come into contact with it. A 2017 United States Water Quality Inventory revealed that more than half of the country’s rivers, bays and estuaries were considered unsafe for at least one use and that fecal contamination was the culprit in several of these cases.
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“If sewage enters clean waters and people are exposed to it, it can lead to illness in humans,” study co-author and civil engineer Lauren Kennedy of the University of Texas at El Paso. said in a statement. “Our research tries to understand which factors can prevent pathogens from infecting people. In other words: how long will it take before the water is safe for recreation again without any form of outside intervention?”
The team hypothesized that the zooplankton could play a role in cleaning up dirty water. The organisms are naturally present in water and can graze on microorganisms through fecal contamination. This in turn inactivates the dangerous organisms and “cleans” the water.
In the studythey added one virus called MS2 and the bacteria E.coli to freshwater and saltwater samples taken from the San Francisco Bay area. According to Kennedy, both the virus MS2 and the bacteria E.coli are considered useful indicators for scientific research because they are usually present in high concentrations in sewage. Their presence is usually a sign that there is fecal contamination in the environment. The water samples the team used naturally contained both larger particles such as zooplankton, sand and dirt, as well as smaller or dissolved particles such as salt.
The large particles – including the zooplankton –seemed to have no significant effect about the inactivation of the MS2 and E.coli pathogens in the water. It was those smaller articles that had a bigger impact. Both the added virus and bacteria were inactivated to a greater extent in water with high salinity, such as ocean water taken from San Pedro beach.
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This study gives scientists new insight into some of the limitations of using zooplankton as a natural way to clean up polluted water. In one follow-up studythe team will focus on the impact of salinity on pathogens that survive in polluted water.
“I am proud that we have been able to offer a different perspective for surface water remediation,” said Kennedy.
