How do you classify the different biological zones in rivers and streams vertically?

Based on the solar light that enters the oceans and river

Explanation:

River ecosystem of a couple of both biotic and abiotic components among the plants and animals involving there physical and chemical properties. As the flow of water is unidirectional, it's in state of continuous physical change and has a high degree of spatial and temporal heterogeneity. River sources are small, and in the areas of mountain streams, are steep and erosional. In temperate environments, overhead tree canopy conditions result in cool, well-oxygenated streams.  All sorts of communities like coastal, estuaries, reefs and deep-sea trenches like Mariana trench which has no sunlight has a distinct type of community.

Your answer would be 625,000,000.