Multiple approaches to microbial source tracking in tropical northern Australia.
Bottom Line: To address this, we sampled sewage outfalls, other potential inputs, such as urban rivers and drains, and surrounding beaches, and used genetic fingerprints from E. coli and enterococci communities, fecal markers and 454 pyrosequencing to track contamination sources.Two other treated effluent discharges did not appear to influence sites other than those directly adjacent.Generally, connectivity between the sites was observed within distinct geographical locations and it appeared that most of the bacterial contamination on Darwin beaches was confined to local sources.
Affiliation: Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.Show MeSH
Related in: MedlinePlus
Mentions: E. coli, enterococci and fecal coliform concentrations for each of the 30 study sites (Fig. 1) are detailed in Table 1 and illustrated in Figure 3. Elevated bacterial counts were detected at the Leanyer-Sanderson sewage outfall (site 1) but not in its receiving waters (site 2). The Larrakeyah sewage outfall (site 27) had very high counts, while the bacterial counts at nearby Doctors Gully (site 28) and Lameroo Beach (site 29) were slightly elevated. The third sewage outfall (Ludmilla; site 14) had very low counts, probably due to the chlorine gas treatment used at the plant. A cluster of high readings occurred in the lower reaches of Rapid Creek (sites 6–10), although counts at the adjacent Rapid Creek Beach (site 4) were low. Another cluster of higher readings was seen for Mindil Beach (site 23) and several drains and waterways that flow onto the beach (sites 21, 22, and 25). Fannie Bay beach (sites 15 and 16) had high bacterial counts in the past, however, on our day of sampling counts were low. The two beaches selected as references (sites 3 and 30) had very low bacterial counts.
Affiliation: Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, Northern Territory, Australia.