Question

1. answer these questions:

agricultural runoff can carry fertilizers into lakes and streams. this runoff can cause algae populations to greatly increase. which effect does this change in the algae population sizes most likely have on affected lakes and streams?

• an increase in water level
• an increase in water clarity
• a reduction in dissolved oxygen needed by fish and shellfish
• a reduction in temperature variations near the water’s surface

Explanation:

When fertilizers cause algal blooms, the algae eventually die and decompose. Decomposers use oxygen during decomposition, which reduces the dissolved oxygen in the water. This affects fish and shellfish that need dissolved oxygen. An increase in water level isn't caused by algal blooms. Algae would decrease water clarity, not increase it. Algal blooms don't reduce temperature variations at the water's surface.

Answer:

a reduction in dissolved oxygen needed by fish and shellfish