Multiple choice

which one of the following is NOT an indicator of high levels of dissolved oxygen

  1. perch

  2. mayfly larva

  3. caddisfly larva

  4. leach
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Leeches are highly tolerant of low-oxygen conditions and pollution. Perch, mayfly larvae, and caddisfly larvae are sensitive species that require high levels of dissolved oxygen.

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