The phytoplankton of a lake would be found in highest numbers in the ________ zone.

• A. benthic
• B. littoral
• C. profundal
• D. limnetic

Answer: (D)

Verified step by step guidance

1. Understand the different zones of a lake: The lake is divided into several zones based on depth and light penetration. These include the benthic, littoral, profundal, and limnetic zones.
2. Define the benthic zone: This is the bottom of the lake, where light does not penetrate, and it is primarily inhabited by decomposers and bottom-dwelling organisms.
3. Define the littoral zone: This is the shallow, near-shore area of the lake where sunlight reaches the bottom, allowing for the growth of rooted plants and algae.
4. Define the profundal zone: This is the deep, dark region of the lake where light does not penetrate, and it is typically devoid of photosynthetic organisms.
5. Define the limnetic zone: This is the open water area of the lake where sunlight penetrates, allowing for photosynthesis. Phytoplankton, which are photosynthetic organisms, are most abundant in this zone because they require sunlight to produce energy.