| Chlamys farreri is a promising species, which has been widely cultured in the neritic waters in China. Scallop farming has been bringing not only great economic benefit, but also great burden for the neritic ecosystem due to filtering food and releasing metabolic production. This result must be contributed to self-pollution of cultivation. With the aim of decreasing of self-pollution effects of cultivation, an increasing number of studies have been performed. Bivalves affect nutrient dynamics in freshwater systems, through excretion as well as biodeposition of feces and pseudofaeces, and nitrogen and phosphorus were the two elements which is more important than any other components, so the study on the feature of nitrogen and phosphorus excretion of scallop is very necessary, especially for scallop farming sea area.There are two excretion forms for scallop, dissolve excretion and particle excretion. Dissolve excretion is released by urine, while particle excretion is expelled by feces. The results of study on the excretion features of farreris scallop {Chlamy farreri) under simulated natural condition are studied with the aim of learning the modality of nitrogen and phosphorus excretion, and their excretion rates. Moreover, the investigation of the relationship among water temperature, shell length and alga concentration was also carried out, and make some mathematics models about several factors.The experimental data show the excretion rates of DTN and PTN were2.12μg/h/ind plus or minus 1.21μg/h/ind and 0.78μg/h/ind plus or minus 0.63μg/h/ind, and the excretion rates of DTP and PTP were 0.41μg/h/ind plus orminus 0.33μg/h/ind and 0.17μg/h/ind plus or minus 0.15μg/h/ind. The content of DTN and PTN were 72.9% and 27.1%, thereinto, the content of ammonia was 49.6%, while the content of DTP and PTP were 70.4% and 29.6%. C.farreri increased the production of feces and especially pseudofaeces at all chlorophyll a concentrations tested, and the ratio of pseudofaeces to faece expelled increased with increasing chlorophyll a concentrations, especially when the chlorophyll a concentrations reached 54.07(j.g/L plus or minus 6.92ug/L.The degradation rates of TN and TP were 0.235mgd"' and 0.061mgd"1. The degradation rate constant of COD varied from 0.066 to 0.12,and mean was 0.09. The individual total nitrogen excretion rate of the scallop are positively correlated with the shell length, body weight and temperature in range of 9.2-27.3 °C. After considering dissolve and particle excretion of nitrogen, the excretion rates of C.farreri was related to shell length by the allometric equations, R=aWb. The interaction of temperature and shell length with Nd or Np could be described by the model(l) and (2),and the interaction of temperature ,shell length and chlorophyll a concentrations could also be described by the two model (3) and (4). Nd = 139.91LnT+212.10LnL-633.51 (1)Np=67.58LnT+54.57LnL-243.53 (2)Nd=2.945LnT-LnL+4.933LnC-15.068 (3)Np=232.638LnT+59.645LnL-2.460LnC-2.684TL+0.532LC (4)-0.060CT-0.015TLC-616.406With a part of the results, a dynamic model for dissolved environmental capacity in Sungo Bay was established and was used to set up the calculation method of environmental capacity for N and P. The main conclusions indicated that the environmental capacity of Sungo Bay is 4360.It/a; The N input is 2942.3t/a, and the percentage of excretion by scallop is 37.4%; The P input is 268.9t/a, and the percentage of excretion by scallop is43.9%. So the pollution pressure that the excretion of nitrogen and phosphorus by scallop brings should not be ignored.
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