Wednesday, December 4, 2013

Man is at the same level as anchovy in the chain ... -

Man is traditionally considered the last link in the food chain. But “this is wrong,” says a French research team, for whom man is actually at the same level as anchovy, far from a top predator.

In reaching this finding some little confusing, Ifremer team / Institute of Research for Development / Agrocampus West was calculated for the first time the “trophic level” rights. It is this index that determines the position of a species in the food chain.

Far polar bear or orca

“It is true that no one is above man,” in any case the person to eat, admits to AFP Sylvain Bonhommeau, lead author of the study published this week in the Reports of the National Academy of Sciences (PNAS). But it is not the custom superpredator we present, at least in terms of food.

trophic level of a species depends on its diet. Plants, which are the primary producers of organic matter, belong to the first trophic level. Herbivores under the second level. Carnivorous predators that feed on herbivores, point to higher levels. Trophic level represents “the number of intermediaries between primary producers and predators,” explained IFREMER and IRD in a statement.

using FAO data on human consumption for the period 1961-2009, the researchers defined a trophic level of 2.2 for humans, which is close to an anchovy or pig level. Top predators, such as polar bears and orca, may in turn reach an index of 5.5.

Food composed of 97% plant in Burundi

The researchers also analyzed the differences in human trophic level geographies. Burundi is the country with the lowest index: with a score of 2.04, diet Burundians “must be made up almost 97% of plants,” say the researchers. Iceland gets however the highest (2.54) score, which is a predominantly carnivorous diet (over 50%), ie very rich in fish.

If man is not, contrary to common belief, a top predator, the researchers found, however, an increase of 3% of the human trophic level over the past fifty years. “This increase shows that the human diet has a greater impact on the ecosystem,” the researchers said.

Sylvain Bonhommeau also notes that “the impact of man on is much larger than its supply ecosystem.”


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