The answer is : The amount of available resources in the ecosystem must change at a predictable rate. This is the one criteria that must be met in order for an ecosystem to be stable. A good example would be a balanced aquarium. Energy is supplied by Light, plants changed the light energy into glucose. Recycling happens during photosynthesis and respiration, wherein plants give off oxygen, which in turn is used by the fish during respiration. Then, fish release carbon dioxide which is used by the plants.