RESEARCH ON BUDGETS,OCCURRENCE,AND DISTRIBUTION OF NITROGEN AND PHOSPHORUS IN ECOLOGICAL AQUACULTURE PONDS FOR SEA CUCUMBER AND SHRIMP
The effects of ecological aquaculture on budgets,occurrence,and distribution of nitrogen and phosphorus in aquaculture ponds for sea cucumber and shrimp were studied using a land-based network enclosure tracking system.Sea cucumber Apostichopus japonicus(density:10,15 ind./m2)and shrimp Fenneropenaeus chinensis(density:0,2,4,8 ind./m2)were selected for experiment.Results show that the harvested showed no significant difference in the weight and survival rate of A.japonicus among group(P＞0.05).The weight and survival rate of F.chinensis were relatively low with significant difference(P＜0.05).Water exchange was the main pathway for nitrogen and phosphorus budgets in the system.The budgets of water layer,Chladophora,leakage,sediment accumulation,A.japonicus,F.chinensis,and adsorption were relatively small,and no significant difference among groups(P＞0.05).The nitrogen and phosphorus loads in the water environment of the system were-0.7 g/m2 and-0.5 g/m2,respectively.The nitrogen and phosphorus contents in the sediment of the system showed significant seasonal changes,and the seasonal variation trends of total nitrogen(TN),ammonium nitrogen(NH4+-N),total phosphorus(TP),and organic phosphorus(O-P)content were basically consistent,with low values in May and November and high values in July and September.The seasonal variation trend and vertical distribution trend of characteristic phosphorus were more complex.The correlation analysis showed that the occurrence and distribution of characteristic phosphorus in sediments were closely related to the content of TP,TN,and NH4-N.This study preliminarily revealed the changes in nitrogen and phosphorus in the ecological aquaculture system without feeding A.japonicus and F.chinensis,to provide a basic theoretical basis for green ecological aquaculture in seawater.
ecological aquaculture of sea cucumber and shrimpnitrogen and phosphorus budgetssedimentthe occurrence and distribution of nitrogen and phosphoruscorrelation
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