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A 9-week feeding trial was conducted to determine the optimal dietary vitamin C requirement and its effects on serum enzymes activities and bacterial resistance in the juvenile yellow drum Nibea albiflora (initial weight 33.2 ± 0.10 g). Six practical diets were formulated containing vitamin C 2.1, 45.3, 89.6, 132.4, 178.6 and 547.1 mg kg−1 diet supplied as l-ascorbyl-2-monophosphate. The fish fed 547.1 mg kg−1 diet showed a significantly higher survival than that fed 2.1 mg kg−1 diet. The weight gains and specific growth rate of the fish fed 2.1 mg kg−1 diet were significantly lower than those of the fish fed 89.6-547.1 mg kg−1 diets. The liver vitamin C concentration firstly increased with increasing dietary vitamin C supply from 2.1 to 178.6 mg kg−1 diet and then stabilized. The serum superoxide dismutase activities of the fish fed 547.1 mg kg−1 diet were significantly lower than those of the fish fed 2.1-89.6 mg kg−1 diet. The fish fed 2.1 mg kg−1 diet had a significantly higher alkaline phosphatase activity than those in the other groups except the 45.3 mg kg−1 group. Fish that received diets containing vitamin C at 547.1 mg kg−1 had significantly higher nitro blue tetrazolium and lysozyme activity, and fish that received diets containing vitamin C at 45.3-547.1 mg kg−1 exhibited resistance against Vibrio alginolyticus infection. The dietary vitamin C requirement of the juvenile yellow drum was established based on broken-line model of weight gain to be 142.2 mg l-ascorbyl-2-monophosphate kg−1 diet. [ABSTRACT FROM AUTHOR]

China is the world's largest producer of aquatic animals, and the Taihu Lake area is one of the most important contributors within China. To obtain the basic information needed to minimize environmental impacts of aquaculture, the water quality and volume of effluents from 48 ponds used for raising crab, shrimp, river prawn, black carp, grass carp and turtles near Taihu Lake were monitored, and their pollutant loads were estimated. Effluent volumes ranged from 12.7 ± 1.7 (crab) to 50.9 ± 15.8 (turtle) thousand tons ha−1 year−1. The concentration of pollutants in the effluents often exceeded acceptable limits for Taihu Lake. Crab ponds produced the lowest gross loads of total nitrogen, total phosphorus, chemical oxygen demand and total suspended solids, whereas turtle ponds produced the highest. The net loads of monitored pollutants comprised only 4-53% of the gross loads in crab ponds, but > 50% in other species ponds. Results indicate that the pollutant loads discharged from aquaculture ponds around Taihu Lake are mild, but precautions are still needed to treat the wastewater. Connecting the ponds in series with crab ponds downstream is a feasible way to decrease pollutant loads. [ABSTRACT FROM AUTHOR]

Particulate organic carbon (POC) plays an important role in the global carbon cycle. The POC in the Changjiang Estuary and adjacent coastal region of the East China Sea (ECS) is dominated by riverine input and marine production and is significantly influenced by the three gorges project (TGP). A coupled physical-biogeochemical model was used to evaluate TGP's impact on POC. The results demonstrate that TGP regulates the area influenced by diluted water and POC through direct river and sediment discharge and affects the ecosystem. From the early to later TGP construction periods, the surface region with high-POC concentration (>40 μmol L−1) decreases by 20.5% in area and 11.5% in concentration. Meanwhile, POC in the whole water column decreases from 19.5 to 17.8 μmol L−1. By contrast, the concentrations of chlorophyll-a (Chl-a) and related nutrients increase. A three end-member mixing model based on quasi-conservative temperature and salinity is used to quantify relative contributions of different water sources to POC in our research area. We also estimate the biological POC production by the difference between the physical-biogeochemical model predicted POC and three end-member model mixing POC. The result demonstrate that under the regulation of TGP in the later period, the decrease of sediment load increases water transparency, which favors photosynthesis and oceanic biological produced POC. In addition, over 70% of the areas have C/Chl-a > 200 and high C/N ratios, which are circumstantial evidences that organic detritus and terrestrial input sources still dominate in the Changjiang Estuary and adjacent coastal ECS but are influenced by TGP's regulation. [ABSTRACT FROM AUTHOR]