Temperature is the abiotic factor that is changing the ecosystem. Both the top layer temperature and the overall temperature of the lake are increasing. The warmer temperatures have delayed the yearly springtime mixing of warm and cold water in the lake.
So the answer must be 9 for an example 50% of 18 is 9 because to find 50% of something simply divide by 2 .10% of 90 is 9 because to find 10% of something divide by 10. 25% of 36 is 9 because you divide by 4 to get 25% of anything.
