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| Phosphorus Cycling in Intensive Grass Carp Culture |
| ZHANG Man,GU Qianhong,LI Xuejun,SONG Dongying,ZHOU Chuanjiang |
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Abstract Understanding of the phosphorus cycling approach in aquaculture ecosystem provides theory basis with improvement of cultural benefits and decrease in phosphorus emissions . We therefore manipulated different phosphorus concentrations in fodder to study the influences of phosphorus concentration on grow th ,feed efficiency and phosphorus cycling in intensive aquaculture ponds of grass carp Ctenopharyngodon idellus .Fish in two treatment groups (A and B groups) were fed compound feed containing phosphorus content of 1 .02% and 0 .52% . A ten‐weeks observation showed that the feed efficiency was 68 .4% and mass increasing rate was 72 .3% in group A .In contrast ,the feeder efficiency was 77 .3% and mass increasing rate was 74 .3% in group B . There were significantly higher fodder efficiency and greater yield in group B than those in group A .Treatment with low phosphorus fodder led to more phytoplankton biomass ,suggesting that it could pump phosphorus from sediments and accelerate the efficiency of material circulation through food chain .The result explained the reason why treatment with low phosphorus fodder led to higher fodder efficiency and greater fish field . Increasing phosphorus concentration in fodder was not beneficial to improve fish field in intensive grass carp .On the contrary ,it could lead to more phosphorus retention in the sediment and pollution in the water .Suitable phosphorus contents in fodder can accelerate the grow th of phytoplankton directly ,ultimately getting satisfied fish field and protecting environment simultaneously .
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Received: 25 August 2015
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