The correct sequence of organisms during hydrarch succession is :

Options

A. Phytoplankton-submerged plant - submersed free floating plant stage-reed swamp stage - marsh- meadow stage - scrub stages-forest
B. Scrub stages - forest - reed swamp stage - marsh - meadow stage -submersed free floating plant stage - submerged plant-phytoplankton
C. Submerged plant-marsh-meadow stage-scrub stages-forest - phytoplankton-submersed free floating plant stage-reed swamp stage
D. Phytoplankton - red swamp stage- scrub stages-forest-submerged plant - submersed free floating plant stage-marsh-meadow stage

Answer

To determine the correct sequence of organisms during hydrarch succession, we need to follow the stages of ecological succession that occur in a wet environment. Here’s a step-by-step breakdown of the sequence:

### Step-by-Step Solution:

1. **Pioneer Species**: The first organisms to colonize a wet area are known as pioneer species. In hydrarch succession, the pioneer species is **Phytoplankton**. These are microscopic plants that float in the water and are the initial colonizers in aquatic environments.

2. **Submerged Plants**: After phytoplankton, the next stage involves the growth of **submerged plants**. These are aquatic plants that grow completely underwater and begin to establish themselves in the habitat.

3. **Free Floating Plants**: Following the submerged plants, the next stage includes **free-floating plants**. These plants float on the surface of the water and are not anchored to the substrate.

4. **Reed Swamp Stage**: As the succession continues, the habitat transitions to the **reed swamp stage**, where reed plants begin to dominate the area, indicating a shift towards more complex vegetation.

5. **Marsh Meadow Stage**: Next, the environment evolves into the **marsh meadow stage**, characterized by the presence of grasses and other herbaceous plants that thrive in wet conditions.

6. **Scrub Stage**: After the marsh meadow stage, the succession progresses to the **scrub stage**, where shrubs and small trees start to appear, further diversifying the plant community.

7. **Climax Community (Forest)**: Finally, the last stage of hydrarch succession is the formation of a **forest**, which represents a stable community with a diverse array of plant and animal life.

### Correct Sequence:
The correct sequence of organisms during hydrarch succession is:
1. Phytoplankton
2. Submerged plants
3. Free-floating plants
4. Reed swamp stage
5. Marsh meadow stage
6. Scrub stage
7. Forest (climax community)