Which of the following would most likely cause

an increase in the number of anaerobic bacteria

in a pond?

A. a decrease in the number of aerobic bacteria in

the pond

B. a decrease in the amount of oxygen dissolved in

the pond

C. a decrease in the temperature of the water in the

pond

D. a decrease in the amount of organic wastes in

the pond

Answer: Option B). a decrease in the amount of oxygen dissolved in

the pond

Explanation:

Anaerobic bacteria are able to survive in the absence of oxygen while aerobic bacteria survive only in the presence of abundant oxygen.

Hence, while reduced levels of dissolved oxygen in the pond decrease the amount of aerobic bacteria like Bacillus; anaerobic bacteria like Actinomyces flourish since they survive on organic substances like methane, cellulose instead.