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Energy transfer between trophic levels!!

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Energy transfer between trophic levels!!

Postby cephie » Sat Jan 28, 2006 8:43 pm

What does the inefficiency of energy transfer between trophic levels in an ecosystem have to do with the biomagnifications of a pollutant by the organisms in that ecosystem?

Please help with this question!
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Postby sachin » Mon Jan 30, 2006 2:44 pm

Think about Human & Pollutin. Plants--pollien grains, cotton.

pollutant magnify through food chain.
of course it hamppers energy transfer by lowering its amount and capasity.

human(waste)> rat> snake> egal> bacteria> earth> plant> rat> human> rat(multiple spread)
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Postby AstusAleator » Mon Jan 30, 2006 9:11 pm

Here's an example.
A plant, in cooperation with symbiotic mycorrhizae and nitrogen fixing bacteria, "begins" the process by using photosynthesis to assemble the various minerals, Nitrogen, CO2, and water that it collects into energy-storing molecules.
A cow comes along and eats the plant. The cow absorbs 70% (just a hypothetical statistic) of the energy stored in that plant. The cow eats 100 more similar plants, digesting and then releasing the remnants as waste.
The cows waste becomes a schmorgasboard (sp?) for various bacteria, fungi, and insects.
The bacteria, fungi and insects become food for other insects, birds, lizards, amphibians, and small mammals.
Those small animals in turn become food for larger animals, and what's left of their bodies becomes food for the fungi, bacteria, and insects again.
The larger animals and scavengers become prey for the top predators.
The cow is killed by a wolf, which absorbs 30% of the stored energy in the cows body and leaves the rest for scavengers, insects, and micro-organisms.
The wolf dies of old-age and is eaten by scavengers, insects, etc.

Now add DDT, a lipid soluble persistant pesticide that is biotransferrable.
Lets say the plants that the cow ate all had DDT in them. Then the cow ate them and got the DDT in it's system. What DDT wasn't absorbed into the cows body, was released in the waste and eaten by the small invertebrates and microbes. The DDT was then transferred to the larger vertebrates, and so on up the food chain.
So because these plants were sprayed with DDT, every time the wolf eats something, it will be getting another dose of DDT in its system, and that DDT will never go away.

Bioaccumulation is particularly severe in aquatic systems, where bottom-feeders or filter feeders absorb heavy metals such as cadmium or mercury. Top-predator fish feed on millions of these tiny invertebrates, and each time theire accumulating more heavy metals in their bodies. Even if the metals don't manifest any negative effects in the fish, the concentrations might be high enough that when a bear or an eagle catches and eats the fish, it may get poisoned.
What did the parasitic Candiru fish say when it finally found a host? - - "Urethra!!"
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