Re: NANFA-- salmon carcass nutrients article

Bruce Stallsmith (fundulus_at_hotmail.com)
Sat, 27 Jan 2001 15:29:03 -0500

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Animals higher up the trophic web tend to concentrate materials from lower
in the web. In isotope studies, this means that top predators will be
isotopically heavier than what they eat. Various plants are the most
significant metabolic "discriminators", and animals reflect the
discriminations of the plants, algaes, etc. that they eat. So in short a
salmon would be expected to be isotopically heavy (N14 is probably 97% of
the total N in the biosphere, N15 about 3%, if I remember correctly off the
top of my head...).

--Bruce Stallsmith
Huntsville, AL

>Thanks! I wonder at what trophic level(s) this is most important. Using
>the salmon example, are marine salmon metabolic systems less discriminatory
>because these fish have to grow large fast? Or is it because that
>discrimination occurred with their food, or their food's food? Or none or
>all, or is it not that simple?
>
>--
>Jay DeLong
>Olympia, WA

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