Dear Friends, I am trying ECOSYSTEM based modelling of Zuari Estuary (Goa, Southwest coast of India) with about 24 ecological groups. The basic inputs were provided and the model was mass balanced (adjusting the biomass of four groups) with Eco trophic efficiencies were kept under one. However, the respiration values are showing negative values and it is given as an error in result display. How should i adjust the input data (Diet matrix or Biomass which has to be adjusted) for making the respiration values to positive and within one.
Hello, in your model the second master equation of Ecopath has been violated (Consumption = production + respiration + unassimilated food)
In my opinion I suggest you to start testing the model including different diet values provided by literature (if you have this data available). Remember which data are the more reliable and avoid changing these. If the respiration values are still negative you will need to reduce the production/consumption ratio by lowering the production/biomass ratio or increasing the consumption/biomass ratio, and/or reduce the proportion of unassimilated food. Find more information about these steps in this link
http://sources.ecopath.org/trac/Ecopath/wiki/EwEugBalancingaModel
Good luck with your model,
I believe that you can reach full elegance with your model. My question is, once done, how it can be practically applied, if at all, in an ever-dynamic, ever-changing, and unpredictable environment, such as river estuary?
sorry for saying that, but are you sure that that approache is really useful? Despite of the use (and misuse) of that models, do they really say something to us? Despite of the overhelming number of papers about do they really im,prove the quality of our comprehension??? An example :10 % of energy transfer from one "trophic" level : as reported in many books (e.g. Colinvaux) the rule of 10% widely applied has no scientific support and the passive application did serious damage in agricultural plans in the so called " developing world". There are heavier problems (if possible) on fisheries models but nobody seems to care
Hello Sreekanth,
Please contact our colleagues in China, for instance Ying Wang at [email protected] as they have been working for many years now on the development of an ecosystem model for the Pearl River Delta in China. A few papers have been published out of it. I can send you the papers if you want. Let me know.
Regards
pierre
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