In the ongoing processes of photosynthesis, respiration, and decomposition in the ocean, all components are recycled except

In the ongoing processes of photosynthesis, respiration, and decomposition in the ocean, all components are recycled except  energy. 
Nearly all photosynthesis in the ocean takes place in the sunlit upper layers, because the deeper , the less light is available.
The depth where the photosynthesis reaches its peak activity varies with the location and the season.

This type of galaxy is an approximately ellipsoidal shape and a smooth, nearly featureless image. they are the largest single star systems, in the universe and are built by the collisions of many smaller galaxies.