Sunlight is essential for every living creature on earth. In the aquatic environment, light serves a variety of critical functions. The light is not only beneficial to plants in the water but also to the animals.
Several studies seem to indicate that both river and ocean fish will use filtered light in their environment for camouflage. They will wait in brighter areas to reduce their visibility to predators. A clear sign that light is crucial for life in the water is that there are significantly fewer varieties of animal species present.
However, sunlight is most important for the plant vegetation in the aquatic environment. Without sunlight, plants are not able to produce their own energy through the process of photosynthesis. The levels of light are more concentrated at the surface of the water. Plants that grow in shallow waters, as well as floating plants, will be more prevalent than plants deeper into the water. Plants will also adapt themselves according to the amount of sunlight present.
Without sunlight, there is no possibility for life to be sustained. In the aquatic environment, the animals use the sunlight as a place to hide, while the plants use natural light to produce fuel.