* Light. Plants need light to photosynthesize, and the amount of light available decreases as you go deeper into the water. This is because water absorbs light, and the more water there is between the plant and the surface, the less light the plant will receive.
* Temperature. The temperature of the water in a pond can vary significantly from the surface to the bottom. In general, the water is warmer near the surface and cooler near the bottom. This is because the sun's heat is absorbed by the surface of the water. Plants that prefer warmer water will tend to grow near the surface, while plants that prefer cooler water will tend to grow near the bottom.
* Nutrients. Nutrients are essential for plant growth, and the amount of nutrients available in a pond can vary from the surface to the bottom. In general, the water is richer in nutrients near the surface. This is because nutrients are often added to the pond from the atmosphere, and they tend to sink to the bottom over time. Plants that require more nutrients will tend to grow near the surface, while plants that require fewer nutrients will tend to grow near the bottom.
* Oxygen. Oxygen is essential for plant growth, and the amount of oxygen available in a pond can vary from the surface to the bottom. In general, the water is richer in oxygen near the surface. This is because oxygen is absorbed from the atmosphere, and it tends to sink to the bottom over time. Plants that require more oxygen will tend to grow near the surface, while plants that require less oxygen will tend to grow near the bottom.
In addition to these factors, the distribution of plants in a pond can also be influenced by the type of pond, the size of the pond, and the surrounding environment.