Re: NANFA-- salmon carcass nutrients article

Bruce Stallsmith (
Sat, 27 Jan 2001 15:29:03 -0500

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

Get your FREE download of MSN Explorer at

/"Unless stated otherwise, comments made on this list do not necessarily
/ reflect the beliefs or goals of the North American Native Fishes
/ Association"
/ This is the discussion list of the North American Native Fishes Association
/ To subscribe, unsubscribe, or get help, send the word
/ subscribe, unsubscribe, or help in the body (not subject) of an email to
/ For a digest version, send the command to
/ instead.
/ For more information about NANFA, visit our web page,