the process of photosynthesis converts light energy into chemical energy that is stored as organic matter in compounds such as carbohydrates,proteins,and lipids.the amount of this stored organic matter produced by algae and other autotrophs is known as primary production,and it supplies food for many creatures,and for the creatures that feed on these creatures,and so on.algae are thus referred to as the grass of the sea,as they form the base of the food chain.