The carrying capacity of a population is the maximum number of individuals that can be supported in a given environment without degrading the habitat. Based on the data provided from the graph for the number of rotifers alone, we can see the following peak values:
- Day 10: 1,700
- Day 12: 3,000
- Day 14: 4,000
- Day 16: 4,200
- Day 18: 4,200
The highest value of rotifers alone is 4,200, observed on Day 16 and maintained on Day 18. Therefore, the flask’s carrying capacity for rotifers in the absence of water fleas is:
4,200.