Question

Which one of the following zones is absent in pond ecosystems?

• A. Littoral Zone
• B. Limnetic Zone
• C. Profundal Zone
• D. Euphotic Zone

Hint:

Associate the zone names with their meaning: "Littoral" relates to the shore. "Limnetic" comes from the Greek for lake. "Euphotic" means "well-lit." "Profundal" comes from "profound," meaning deep. Since ponds are not deep, they lack a profundal zone.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Lentic (standing water) ecosystems like lakes and ponds are vertically zoned based on the penetration of sunlight. The question asks which of these zones is typically absent in a pond.

Step 2: Detailed Explanation of Zones:
- Littoral Zone: The shallow, near-shore area where light reaches the bottom, supporting rooted aquatic plants. All ponds have a littoral zone.
- Limnetic Zone: The open, well-lit water surface area away from the shore, dominated by plankton. Ponds have this zone.
- Euphotic Zone: This is the entire upper layer of water that receives enough sunlight for photosynthesis to occur. It encompasses both the littoral and limnetic zones. Ponds are entirely within the euphotic zone.
- Profundal Zone: This is the deep, aphotic (non-light receiving) zone of water below the limnetic zone. It is too dark for photosynthesis. Because ponds are, by definition, shallow bodies of water, sunlight typically penetrates all the way to the bottom. Therefore, ponds lack a true, permanently dark profundal zone, which is a characteristic feature of deep lakes.

Step 3: Final Answer:
Due to their shallow depth, ponds typically lack a profundal zone. Therefore, option (C) is the correct answer.