There are many producers, consumers and decomposers in the Great Barrier Reef. One major producer is algae, which produces food, which organisms can eat. Also, there are a lot of fish in the Great Barrier Reef and they are consumers. Fish eat many things such as coral, plants and sometimes smaller fish. Finally there are many decomposers in this area such as bacteria and fungi, these decomposers help break down the dead materials in the surface below the water.