In an aquatic ecosystem, the trophic level equivalent to cows in grasslands is

Options

A. Phytoplankton
B. Zooplankton
C. Nekton
D. Benthos

Answer

To solve the question regarding the trophic level in an aquatic ecosystem that is equivalent to cows in grasslands, we need to understand the roles of different organisms in both ecosystems.

### Step-by-Step Solution:

1. **Identify the Role of Cows in Grasslands**:
- Cows are herbivores that feed on grass (the producers in the grassland ecosystem). They occupy the second trophic level, where they consume primary producers.

2. **Understand the Trophic Levels in Aquatic Ecosystems**:
- In an aquatic ecosystem, the primary producers are phytoplankton (small, free-floating photosynthetic organisms).
- The next trophic level consists of herbivores that feed on these producers. In aquatic ecosystems, these herbivores are known as zooplankton.

3. **Compare Trophic Levels**:
- Since cows in grasslands are herbivores at the second trophic level, we need to find the equivalent herbivore in the aquatic ecosystem.
- Zooplankton, which feed on phytoplankton, serve the same role as cows do in grasslands.

4. **Evaluate Other Options**:
- Phytoplankton are producers and cannot be equivalent to cows.
- Nekton refers to actively swimming organisms (like fish) that are typically carnivores, not herbivores.
- Benthos are organisms that live on or in the bottom of water bodies, often acting as decomposers, and do not fit the herbivore category.

5. **Conclusion**:
- The trophic level in an aquatic ecosystem that is equivalent to cows in grasslands is **zooplankton**.

### Final Answer:
The correct answer is **zooplankton**.

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