Question

Eutrophication is often the result of _______.
a.
increases in animal populations
b.
lack of oxygen in the water
c.
fertilizer runoff entering aquatic ecosystems
d.
a decrease in phytoplankton populations

Answer 1

c. fertilizer runoff entering aquatic ecosystems

Explanation: Excess nutrients (particularly nitrogen and phosphorus) from fertilizers stimulate algal and phytoplankton blooms; when these organisms die and decompose, decomposition consumes oxygen, causing hypoxia and other problems.