I have delta N for Snail, 3 source organisms (organic matter from phytoplankton; benthic microalgae and peryphyton); primary consumers (zooplankton) and tertiary consumer is Hilsa fish of different sizes.
May I apply TP= [(deltaN primary consumers -deltaN primary producers)/3.4]+1 ( Post DM (2002) Using stable isotopes to estimate trophic position: Models, methods, and assumptions. Ecology 83:703–718)
If so, how can I calculate trophic transfer from primary producers to zooplankton, fish?
Should I use the average delN value of zooplankton as the primary consumer and the average delN value of each primary producers?
1. Yes
2. In my opinion, there is only one way for zooplankton getting nutrient (from the primary producer) whilee the fish may get nutrient from both primary producers and primary consumers. I think it can not be calculated by using delta N only. How about carrying out a indoor experiment and calculating the biomass% of primary producers and consumers intaken by fish directly.
3. Average value is OK
The attached file may help you.
2. You can consider a one-isotope mixing model and take into account trophic enrichment factors to estimate trophic contribution from producers to consumers.
You are exactly right Dr. Frank. But I have 3 producers (phytoplankton, benthic microalgae and peryphyton), 1 primary consumer and 1 predator (fish). Is there any publication relating to this?
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