Which one of the following exhibits least productivity?

Options

A. Salty marshes
B. Grasslands
C. Open oceans
D. Coral reefs

Explanation

To determine which of the following options exhibits the least productivity, we need to understand the concept of productivity in an ecosystem. Here’s a step-by-step solution:

### Step 1: Understand Productivity
- **Definition**: Productivity refers to the rate of production of biomass in an ecosystem, which is typically expressed in terms of mass per unit area (e.g., grams per square meter).
- **Factors Influencing Productivity**: The main factors that influence productivity include sunlight, water, carbon dioxide, and various nutrients.

### Step 2: Analyze Each Option
- **Option 1: Salty Marshes**
- Salty marshes are ecosystems that consist of brackish and salty water.
- They are characterized by the presence of halophytes, which are plants adapted to high salinity and fluctuating water levels.
- **Productivity**: Salty marshes generally have high productivity due to the availability of nutrients and sunlight.

- **Option 2: Grassland**
- Grasslands are terrestrial ecosystems dominated by grasses.
- **Productivity**: They have an annual productivity ranging from about 200 to 1000 grams per square meter, which is relatively low compared to other ecosystems.

- **Option 3: Open Oceans**
- Open oceans cover a vast area but have varying productivity levels.
- **Productivity**: While they contain nutrients, deeper parts of the ocean receive very little sunlight, leading to lower productivity overall.

- **Option 4: Coral Reefs**
- Coral reefs are highly diverse and biologically rich ecosystems found in shallow marine waters.
- **Productivity**: They exhibit some of the highest productivity levels due to their complex structures and the abundance of sunlight.

### Step 3: Compare Productivities
- Based on the analysis:
- Salty Marshes: High productivity
- Grassland: Low productivity (200 to 1000 g/m²)
- Open Oceans: Low productivity due to depth and light limitations
- Coral Reefs: High productivity

### Step 4: Identify the Least Productive Ecosystem
- Among the options analyzed, grasslands have the lowest productivity, but open oceans also have low productivity due to depth.
- However, considering the specific productivity values, grasslands exhibit the least productivity compared to the other ecosystems listed.

### Conclusion
The ecosystem that exhibits the least productivity among the options provided is **Grassland**.

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