Hi all…I learned today what ‘poikilothermic animals’ are (those with body temperatures that vary with the ambient environmental temperature, such as fish, frogs, and snails) and why, as drinking water professionals, we should care. It is best summarized in the authors’ words:

“The current fecal indicator concept is based on the assumption that the standard fecal indicator bacteria Escherichia coli, etc…multiply significantly only in the guts of humans and other warm-blooded animals and can therefore indicate fecal pollution and the potential presence of pathogens from those groups. The findings of the present study showed that fecal indicator bacteria can also occur in high concentrations in poikilothermic animals indicating that a reconsideration of this long-standing indicator paradigm is needed. The study suggests that poikilotherms must be considered to be potential primary sources of fecal indicator bacteria in future studies.”

Bill

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Poikilothermic Animals as a Previously Unrecognized Source of Indicator Bacteria in a Backwater Ecosystem of a Large River

Frick C, Vierheilig J, Linke R, Savio D, Zornig H, Antensteiner R, Baumgartner C, Bucher C, Blaschke AP, Derx J, Kirschner AKT, Ryzinska-Paier G, Mayer R, Seidl D, Nadiotis- Tsaka T, Sommer R, Farnleitner AH. 2018.
Appl Environ Microbiol 84:e00715-18. https://doi.org/10.1128/AEM.00715-18
http://aem.asm.org/content/84/16/e00715-18.abstract?etoc 

ABSTRACT:

“Quantitative information regarding the presence of Escherichia coli, intestinal enterococci, and Clostridium perfringens in poikilotherms is notably scarce. Therefore, this study was designed to allow a systematic comparison of the occurrence of these standard fecal indicator bacteria (SFIB) in the excreta of wild homeothermic (ruminants, boars, carnivores, and birds) and poikilothermic (earthworms, gastropods, frogs, and fish) animals inhabiting an alluvial backwater area in eastern Austria. With the exception of earthworms, the average concentrations of E. coli and enterococci in the excreta of poikilotherms were equal to or only slightly lower than those observed in homeothermic excreta and were 1 to 4 orders of magnitude higher than the levels observed in the ambient soils and sediments. Enterococci reached extraordinarily high concentrations in gastropods. Additional estimates of the daily excreted SFIB (E. coli and enterococcus) loads (DESL) further supported the importance of poikilotherms as potential pollution sources. The newly established DESL metric also allowed comparison to the standing stock of SFIB in the sediment and soil of the investigated area. In agreement with its biological characteristics, the highest concentrations of C. perfringens were observed in carnivores. In conclusion, the long-standing hypothesis that only humans and homeothermic animals are primary sources of SFIB is challenged by the results of this study. It may be necessary to extend the fecal indicator concept by additionally considering poikilotherms as potential important primary habitats of SFIB. Further studies in other geographical areas are needed to evaluate the general significance of our results. We hypothesize that the importance of poikilotherms as sources of SFIB is strongly correlated with the ambient temperature and would therefore be of increased significance in subtropical and tropical habitats and water resources.”