Yes i agree I would not be as concerned with bacteria dying due to lack of ammonia.
I would be more concerned with power failure personally with my aqua clear draining back into my aquarium and drying out my filter which would kill those bacteria.
This is understanding the fact that beneficial bacteria are present thurought the aquarium. However, in a newly established aquarium one in which the biofilter is just establishing a sufficient amount of bacteria to nitrify ammonia that even slight decrease in bacteria could be enough to cause elevated ammonia and affect one's fish
-I do Agree that not all bodies of water depend Mechanical filtration systems otherwise how would you have striving and functional ponds or lakes.. but my line of thought is..?which may be completely wrong..? It really depends on the environment in which the specific strand of nitrifying bacteria grew.. for example the nitrifying bacteria in a swamp have developed and multiplied in an environment with almost no fresh water flow where as the bacteria that have grown in one's filter are a type that have developed and grown in an environment with constant High Water flows with higher Oxygen Saturation
Now if you stop that fresh o2 supply constantly flowing over Bacteria that have a developed a pretty rapid metabolism due to the High oxygen rich water flow of a filter my assumption would be that the bacteria become ineffective and hibernate or die.?
If you couple that with co2 build up and secondary decreased partial pressure of o2 in the water and you have a potetional for your biosystem to have taken a hit.. i do believe that is why some people have experienced "mini cycles" after power outages of even just 8-12 hrs.. of course along with altered temp and other influences
