The Importance of Ecosystems to All Life

All ecosystems are important to all life, regardless of how big the particular ecosystem is. Freshwater aquatic ecosystems account for a minority of global aquatic ecosystems, with most being saltwater, but their health is critical to the planet and to human life. Ecosystems depend on all parts to work the way they are supposed to. If one part of the ecosystem goes away, whether it be through death or through emigration, then the whole ecosystem can suffer as a result. For example, the amount of plants available changes the amounts of nutrients available, and the number of predators available changes the amounts of prey and therefore plants available. Small changes can have big effects. Overall, the factors that determine the health and sustainability of an aquatic ecosystem include the energy flow, nutrient cycling, biodiversity and interactions among all the components of the ecosystem.

One major driver of the energy in an ecosystem is light (Sterner and Hessen, 1994, pp. 1--29), usually in the form of sunlight. Sunlight, in turn, makes photosynthesis possible, which is very important to all ecosystems. Photosynthesis is so important, in fact, that it is considered to be the basis for most ecosystems. Photosynthesizers (plants, algae, some bacteria), form the first trophic level and are the foundation of the energy flow within an ecosystem ()Energy flows upward to the next trophic level, the herbivores, which eat the plants, and eventually to the highest trophic levels occupied by carnivores. At each level, energy is lost through metabolism of the organisms. When organisms in the higher trophic levels die, some of their energy is returned to the system as they are broken down by detritivores.

Plants can have other effects with...

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