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Abstract:
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Controlling the inorganic nitrogen by manipulating carbon /
nitrogen ratio is a method gaining importance in aquaculture
systems. Nitrogen control is induced by feeding bacteria with
carbohydrates and through the subsequent uptake of nitrogen from
the water for the synthesis of microbial proteins. The relationship
between addition of carbohydrates, reduction of ammonium and the
production of microbial protein depends on the microbial conversion
coefficient. The carbon / nitrogen ratio in the microbial biomass is
related to the carbon contents of the added material. The addition of
carbonaceous substrate was found to reduce inorganic nitrogen in
shrimp culture ponds and the resultant microbial proteins are taken
up by shrimps. Thus, part of the feed protein is replaced and feeding
costs are reduced in culture systems.The use of various locally available substrates for periphyton
based aquaculture practices increases production and profitability .However, these techniques for extensive shrimp farming have not so far been
evaluated. Moreover, an evaluation of artificial substrates together
with carbohydrate source based farming system in reducing inorganic
nitrogen production in culture systems has not yet been carried-out.
Furthermore, variations in water and soil quality, periphyton
production and shrimp production of the whole system have also not
been determined so-far.This thesis starts with a general introduction ,
a brief review of the most relevant literature, results of various
experiments and concludes with a summary (Chapter — 9). The
chapters are organised conforming to the objectives of the present
study. The major objectives of this thesis are, to improve the
sustainability of shrimp farming by carbohydrate addition and
periphyton substrate based shrimp production and to improve the
nutrient utilisation in aquaculture systems. |