Asellus aquaticus as a Potential Carrier of Escherichia coli and Other Coliform Bacteria into Drinking Water Distribution Systems

Abstract

Individuals of the water louse, Asellus aquaticus, enter drinking water distribution systems in temperate parts of the world, where they establish breeding populations. We analysed populations of surface water A. aquaticus from two ponds for associated faecal indicator bacteria and assessed the risk of A. aquaticus transporting bacteria into distribution systems. Concentrations of up to two E. coli and five total coliforms·mL−1 were measured in the water and 200 E. coli and >240 total coliforms·mL−1 in the sediments of the investigated ponds. Concentrations of A. aquaticus associated bacteria never exceeded three E. coli and six total coliforms·A. aquaticus−1. During exposure to high concentrations of coliforms, concentrations reached 350 coliforms·A. aquaticus−1. A. aquaticus associated E. coli were only detected as long as E. coli were present in the water and sediment. The calculated probability of exceeding drinking water guideline values in non-disinfected systems by intrusion of A. aquaticus was low. Only in scenarios with narrow pipes and low flows, did total coliforms exceed guideline values, implying that the probability of detection by routine monitoring is also low. The study expands the knowledge base for evaluating incidents with presence of coliform indicators in drinking water by showing that intruding A. aquaticus were not important carriers of E. coli or other coliform bacteria even when emerging from faecally contaminated waters.

Building on 150 Years of Knowledge: The Freshwater Isopod Asellus aquaticus as an Integrative Eco-Evolutionary Model System

“…For instance, the species is resilient to high levels of both organic and chemical pollution (Aston and Milner, 1980;Van Ginneken et al, 2017, 2019, and is able to bioaccumulate metals (Elangovan et al, 1999;Rauch and Morrison, 1999) -making it a well-suited study system also in ecotoxicology. There is a vast number of insightful studies exemplifying the relevance of this species for water quality assessment and for ecotoxicology (e.g., Rauch and Morrison, 1999;MacNeil et al, 2002;Christensen et al, 2013;Van Ginneken et al, 2017), as well as a recent review highlighting A. aquaticus as a model for biomonitoring (O'Callaghan et al, 2019; Figure 1), but we do not cover these aspects further here.…”

Water Lice and Other Macroinvertebrates in Drinking Water Pipes: Diversity, Abundance and Health Risk

“…The linkage of harmful bacteria and the occurrence of macroinvertebrates in drinking water networks have been intensively investigated, with most studies focusing on microbial colonization of the gut [24,29,42]. Moreover, the guts of macroinvertebrates other than those found in this study have been found to host harmful bacteria.…”

“…are the dominant bacteria in the guts of water lice [46], indicating that these bacteria are inhabitants of the gut and therefore proliferate in water lice. Asellus aquaticus takes up E. coli from water and sediment as well, but these microbes do not remain for a long time and the overall number of E. coli in the guts of Asellus aquaticus seems to be low [42].…”

Effects of anthropogenic stress on hosts and their microbiomes: Treated wastewater alters performance and gut microbiome of a key detritivore (Asellus aquaticus)

“…It is conceivable that A. aquaticus could serve as a vector for pathogenic bacteria, as seen in some other invertebrates (Alonso et al, 1999 ; Brassinga et al, 2010 ; Gismervik et al, 2014 ). In this regard, the role of A. aquaticus and of other organisms as potential carriers of bacteria into drinking water systems (where A. aquaticus has been reported; Christensen et al, 2013 ; Gunkel et al, 2021 ; Levy et al, 1986 ) can be of concern.…”