As a result of human activity, many lakes in Florida have increased levels of nutrients that support algal growth. These algae grow very rapidly, then die and decompose. What impact does this overgrowth of algae most likely have on the lake ecosystem?

The questions have been asked in several important state and regional science exams in the United States. For example: TAKS-Texas Assessment of Knowledge and Skills, New York State Educational Department Regents exams, California Standards Test, etc.