Multiple choice

which one of the following is not an indicator of high levels of DO in a stream?

  1. caddisfly

  2. trout

  3. mayfly

  4. leach

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Leeches are pollution-tolerant organisms that thrive in low-oxygen environments. In contrast, trout, mayflies, and caddisflies are sensitive indicators that require high levels of dissolved oxygen to survive.