Survival of faecal bacteria in Antarctic coastal waters

Abstract

The effect of solar radiation on the survival of Escherichia coli, Salmonella zanzibar and a faecal Streptococcus strain in seawater was tested in laboratory experiments, and survival of E. coli was tested under natural light conditions at Davis Station, Antarctica. Exposure to artificial light of wavelengths 290–800 nm caused a rapid decline in viability of each strain examined. T90 values (the time taken for 90% of the population to be inactivated) were ~50 min, 40 min and 2 h for E. coli, S. zanzibar and the faecal Streptococcus respectively. Selective removal of UV-B wavelengths of (<320 nm) increased survival of E. coli and S. zanzibar, resulting in T90 values of ~2.5 h. Screening out wavelengths of <370 nm (UV-B and most of UV-A) increased T90 values to 5 h for E. coli and 10 h for S. zanzibar. The visible band of the spectrum (400–800 nm) also had deterimental effects on faecal bacteria, when compared with survival in the absence of light. Rates of decline for E. coli in natural light in Antarctica were similar to those from laboratory experiments. However, resuscitation of sub-lethally damaged cells under optimum conditions resulted in greater recovery rates than were observed after exposure to artificial sunlight. Faecal bacteria were rapidly inactivated when exposed to sunlight in Antarctic waters, and as repair mechanisms are unlikely to operate under in situ conditions, resuscitation of sub-lethally damaged cells is improbable.

Influence of Seasonal Environmental Variables on the Distribution of Presumptive Fecal Coliforms around an Antarctic Research Station

“…This and other studies (40,44) have shown the bactericidal effect of solar radiation on a range of sewage microorganism species. Various factors affect the cytotoxic effect of solar radiation on fecal coliforms.…”

“…Fecal bacterial survival rates can vary from a few minutes to many days depending upon the environmental conditions (44). Physical factors affecting the survival of fecal microorganisms in seawater include solar radiation (16,27,28,39,43), temperature (37,41), and salinity (1,35).…”

Anthropogenic impacts on marine ecosystems in Antarctica

“…101,108 To complicate matters, however, natural variations in environmental factors such as algal blooms, salinity, water depth, sea-ice formation, and solar radiation can significantly alter the number of viable microbial sewage indicators detected. 101,114 As an example, the ability of solar radiation to deactivate fecal coliform bacteria in Antarctica is enhanced with increasing exposure time and decreasing radiation wavelength, ozone-column depth, cloud cover, and solar-zenith angle. 115 Although they are essential for the purpose of risk assessment, studies of the impacts of sewage pollution on marine biotas have been performed near only a few Antarctic outfalls.…”

“…The extent of sewage pollution is influenced by the number of people on station generating the waste, 108,110,111 the efficiency of any treatment facility, 98,112,113 and physiographic features affecting dispersal and dilution rates 101,108 . To complicate matters, however, natural variations in environmental factors such as algal blooms, salinity, water depth, sea‐ice formation, and solar radiation can significantly alter the number of viable microbial sewage indicators detected 101,114 . As an example, the ability of solar radiation to deactivate fecal coliform bacteria in Antarctica is enhanced with increasing exposure time and decreasing radiation wavelength, ozone‐column depth, cloud cover, and solar‐zenith angle 115 …”

Impacts of the Mississippi River spillway opening on faecal coliform concentration in Lake Pontchartrain

“…Faecal coliform dynamics in coastal waters is a function of bacterial loading from streams and rivers, mass transport, and bacterial losses due to death and sedimentation. Faecal bacterial survival rates can vary from a few minutes to many days depending upon the environmental conditions (Statham & McMeekin, ). Their disappearance rates from surface waters depend on a number of factors such as the availability of nutrients, temperature, salinity, turbidity, degree of water mixing, solar radiation, predation, and competition (Auer & Niehaus, ; Flint, ; Hood & Ness, ).…”