Abstract:

Aquaculture pond is a relatively closed and fragile ecosystem type, and sediment is an important part of the pond ecosystems. In order to ensure sustainable expansion of freshwater fish farming, it is essential to quantitatively understand how fish farming affects the sedimentary flux of the sedimentary particles between the Ctenopharyngodon idellus ponds and Pelteobaggrus fulvidraco ponds. The sedimentary flux variation and correlations with the culture activities were discussed in this paper. The objective of this study was to quantify the sedimentary flux and analyze nutrient characteristics of sedimentary particles from April to October of 2012 in two aquaculture models ponds. The sedimentary particles were collected respectively by selfmade sediment trap in different aquaculture models ponds. The sedimentary flux of total nitrogen (TN), total carbon (TC), total phosphorus (TP), total organic carbon (TOC) and total organic nitrogen (TON) were also measured in sedimentary particles. Results showed that vertical sedimentary weight of settling particles flux in the Ctenopharyngodon idellus cultured ponds were significantly higher than in the Pelteobaggrus fulvidraco cultured ponds. Meanwhile, the sedimentary weight of the sedimentary particles showed an increasing trend in two aquaculture models ponds. The sedimentary weight was found to range between 10039 to 41466 g/(m2·d) and with an average of 224.46 g/(m2·d) in Ctenopharyngodon idellus cultured ponds, while range from 3414 to 27291 g/(m2·d) and 155.18 g/(m2·d) on average in Pelteobaggrus fulvidraco cultured ponds. Temporal variations of sedimentary flux of TN, TC, TOC and TON were not obvious in two aquaculture models ponds. The sedimentary flux of TN, TC, TOC and TON of the sedimentary particles were significantly higher in the Pelteobaggrus fulvidracocultured ponds than in the Ctenopharyngodon idelluscultured ponds during the culturing period. The content of carbon, nitrogen and phosphorus of sedimentary particles also showed increasing trends during culturing period. The sedimentary flux of TN, TC, TP, TOC and TON in sedimentary particles varied from 37.1 to 194.2 mg/(m2·d), 5.42 to 8.57 mg/(m2·d), 108.9 to 426.1 mg/(m2·d), 225.3 to 1409.7 mg/(m2·d), 26.2 to 172.4 mg/(m2·d) in the Pelteobaggrus fulvidracocultured ponds, and varied from 88.2 to 182.6 mg/(m2·d), 638.1 to 1503.7 mg/(m2·d), 254.4 to 560.5 mg/(m2·d), 567.1 to 1 084.8 mg/(m2·d), 65.5 to 131.9 mg/(m2·d) in the Ctenopharyngodon idelluscultured ponds, respectively. Positive correlation was found among TN, TC, TP, TOC and TON in sedimentary particles matter in the Pelteobaggrus fulvidracocultured ponds. The temporal variation of carbon/nitrogen ratio of sedimentary particles was similar with that in surface sediments in two aquaculture models ponds, which suggested it was similar material source between sedimentary particles and sediment. Therefore, the interaction between cultured fish and environment played an important role during sedimentary particles formation in aquaculture system.