Sam Levy [ardag-w11@ardag.ardom.co.il] wrote:
> I assume that the main carbon source in the slurry fed ponds was
> atmospheric CO2 fixed by primary production. Please correct this assumption
> if it is incorrect.
>
> You state that "most of the energy in chicken manure applied to the
> fishpond turned into methane."  Does this mean that the
> manure fed ponds also relied primarily on atmospheric CO2 as the carbon source?

Dear Friends

Aquatic plants make oxygen in photosynthesis and they obtain hydrogen from
water. Carbon dioxide enters water from the air and from respiration by
bacterial decomposition of organic matter and other living plants and
creatures in the water.

Aquatic bacteria are the smallest microorganisms. The number is great and
widely distributed in the water body. There are a lot in sediment and on
detritus. They are infinitely small, and the fine plankton net can not
collect and count them. That's why the general biological study survey
after does not study them. However, the function of aquatic bacteria is of
great importance. It is essential key link of food chain. If there are no
aquatic bacteria, e.g. putrefying bacteria, there will be no material cycle
and energy flow in water body. In anaerobic conditions most of the energy
in chicken manure applied to fishpond turned into methane and about 40% of
carbon dioxide.

Our center has introduced carbon isotope analysis into research work. We
accurately measured Delta C in organic matter (Fish body, feed and manure).
The results show that filtering and omnivorous fish species in manure
loaded pond obtain carbon from both autotrophic and heterotrophic systems
(60-70% from bacteria; 30-40% from plankton). Common carp obtain carbon
40-50% from silt, bacteria and detritus of chicken manure; 50-60% from
periphyton. (See Guo et al 1987 Selected paper of FFRC CAFS in Chinese).

Li Kangmin