Food Chain/Web - History Of Food Web Research, Structure Of Food Webs, Contaminants In Food Webs, Bioaccumulation
organisms trophic eat level
A food chain is a series of organisms dependent on each other for food; a food web is an interconnected set of food chains in the same ecosystem. Organisms that eat similar foods are assigned to a particular trophic level, or feeding level, within a food web. Food web is a more accurate term because food chains only exist on paper. In nature feeding habits are complex because many organisms feed on different trophic levels. For example humans feed on the bottom consumer level when they eat plants but they also eat organisms from all of the higher trophic levels of the food web.
Additional Topics
Food web research is an extensive area of ecological research. Charles Elton, Raymond Lindeman, Stuart Pimm, Stephen Carpenter, and James Kitchell are some of the major figures in food web research. Charles Elton was an English ecologist who first described the characteristic shape of food webs, which he called the pyramid of numbers. Elton observed that most food webs have many organisms on their…
Within food webs there are three main categories of organisms: producers, consumers, and decomposers. Producers are organisms that synthesize their own organic compounds or food using diffuse energy and inorganic compounds. Producers sometimes are called autotrophs (self-feeders) because of this unique ability. For example, green plants are autotrophs because they manufacture the compounds they ne…
Food webs all over the world have become contaminated by insecticides and other manufactured chemicals. Some of these compounds are having profound effects on the reproduction and behavior of some wild animal species. These chemicals were released into the environment because it was believed that their concentrations were too small to have an effect on organisms. Now we know better. Contamination …
Bioaccumulation refers to the tendency of persistent hydrophobics and other chemicals such as methyl mercury to be stored in the fatty tissues of organisms. When these compounds are spilled into the environment they are rapidly absorbed by organisms in food webs. It is estimated that 99% of pesticides do not reach the target pest which means the chemical ends up in the general environment. If thes…
Biomagnification (also called food web magnification or food web accumulation) is the progressive increase in the concentration of contaminants in organisms as the trophic level increases. This means lower trophic levels generally have smaller concentrations of contaminants than higher levels. This occurs because of the ecological inefficiency of food webs and persistent, hydrophobic contaminants …
Currently there is much debate over what forces control the structure of food webs. Some ecologists believe that food webs are controlled by bottom-up forces referring to the strong connection between primary production and the subsequent production of consumers. For example, adding large amounts of nutrients like phosphorus causes rapid growth of phytoplankton, the primary producers in lakes whic…
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