Food Web for Ecosystem

Food Web

Within the ecological system of the organic compounds are autotrophic organisms (e.g. plants). Plants are eaten by animals, which, in turn, eaten by other animals. Such a sequence is called a food chain; each link of the food chain is called a trophic level. First trophic level organisms are called primary producers. On land, most of the producers make the plant forests and meadows; the water is mostly green algae. In addition, organic matter may produce blue-green algae and some bacteria (Beattie, 307-308).

Second trophic level organisms are called primary consumers, the third trophic level - secondary consumers and primary consumers, etc. - are herbivores (many insects, birds and animals on land, and shellfish in water) and plant parasites (e.g. parasitic fungi). Secondary consumers - carnivorous organisms: predators or parasites. In a typical food chain predators are bigger at every level, and parasites - are smaller.

The term "trophic" is derived from Greek word which means food or predation. Knowledge of fish feeding in the marine environment is a necessary step to understanding their biology and ecology. Knowledge of the diet of a fish used to define a portion of its ecological niche and by extension its habitat. The diet of the species varies mainly depending on the size of individuals, the time of year and habitat. Species that live in the same environment and have the same diet occupy the same ecological niche and are thus in competition. The ability to cohabit may then be crucial to the survival of these species and their productivity. The faithful reconstruction of the food preferences of the species is difficult but this knowledge is essential, especially because it helps explain some changes in their life history (i.e., growth, sexual maturation, reproduction). It also helps to understand how resources are shared between species and the impact of competition between them.

Three major categories of living organisms, determined according to their "trophic function" can be found in an ecosystem: producers able to produce organic matter from inorganic compounds (mainly photosynthetic autotrophs such as phytoplankton), consumers who depend on the organic matter of other agencies (mainly herbivores, carnivores or omnivores) and decomposers can degrade the detrital organic matter (organisms such as bacteria, fungi and certain micro-invertebrates).

There is another group of organisms called reducers. These saprophytes are (usually bacteria and fungi) that feed on the organic remains of dead plants and animals (detritus). Detritus can also ...