| Under the background of the shellfish breeding scale increases year by year, shellfish breeding activities on the influence of the water ecological environment gradually become a hot research topic. Based on the nutrient and carbon distribution pattern of Houtou bay of Gouqi island. Evaluate the eutrophication level of mussel culture zones. Proposed by proven the relationship between breeding activities and nutrient level and distribution pattern of carbon system, analysis the impact of the mussel farming on the water environment. Study the large algae biomass of the culture zones, and combined with the distribution patterns of nutrient and carbon system, discusses the influence of solid raw large algae on culture area water environment. Eventually put forward the proposal on breeding mode of the culture zones, provide the basis for sustainable healthy development of mussel farming. The main research results summarized as follows:1. Evaluated the waters ecosystem health level of the Houtou bayThe waters temperature range in 13.31 ~ 26.01 ℃ during the period 2014-2015, and the annual average temperature 19.56 ℃; The seasonal variation of the salinity distribution is not obvious, and the more stable in the range of 26.18 ~ 28.52. The water p H range in 8.03 ~ 8.77, and the maximum is 8.84 in June, the minimum value is 7.89 in October. Active phosphate concentration in the range of 0.027 ~ 0.038 mg/L, and the ammonium nitrogen concentration in the range of 0.044 ~ 0.111 mg/L. Nitrate nitrogen solubility inorganic nitrogen is the main component of the concentration which in the range of 0.167 ~ 0.344 mg/L, and the nitrate nitrogen concentration in the range of 0.016 ~ 0.031 mg/L; The average eutrophication index(E) is 6.77, and the water in a state of mild to severe eutrophication condition, which present the phosphorus limited eutrophication.2. Analysis of mussel farming and its ecological effect.There are two species of mussels in study area, and the annual output is 15000 tons and 33200 tons respectively, which total output value of about 2.2 billion; The trend of nutrient concentration present the internal high and external low. The DIP and DIN concentration range in August and February is 0.020 ~ 0.042 mg/L,0.025 ~ 0.036mg/L and 0.168 ~ 0.388 mg/L, 0.171 ~ 0.314 mg/L. The DIP and DIN concentration in August higher than February. The p H, DIC, DOC and HCO3— concentration range of study area were 8.36 ~ 8.72, 10.91 ~ 17.69 mg/L, 10.50 ~ 23.55 mg/L, 11.50 ~ 17.58 mg/L in August. And which were 8.13~8.26,24.15~27.12 mg/L,7.10~12.08 mg/L in February. The p H of control plot was significantly lower than mussels maturation culture zones. The HCO3— average concentration in August significantly lower than the slow metabolism period in February. The DIC concentration of aquiculture area was significantly lower than the control plot. The inside DOC concentration level is higher than outside of culture area. The mussels culture zones present obvious carbon sink area; The carbon remove directly through the mussels harvest was 5307 tons, which make carbon tax revenue up to $1.0152 million.3. Analysis of solid raw large algae ecological effect in culture zones.There are more than 60 kinds of solid raw large algae species in the culture zones, and the maximum biomass reached 15800 tons in April. The DIN and DIP concentration range were 0.026 ~ 0.047 mg/L and 0.21 ~ 0.37 mg/L in April, which compared with August, the DIN average concentration was lower, and the DIP average concentration distribution difference was small. The distribution of large algae biomass was negatively correlated with distribution of DIP and DIN. The p H, DIC, DOC and HCO3— concentration range of study area were 8.06~8.38, 13.90~23.63 mg/L,4.49~10.09 mg/L,11.71~23.13 mg/L in April, and the distribution trend of the whole is decrease from internal to the external culture zones. The high value area distribution near the 3, 6, 9 stance, and the effect of large algae proliferation and biomass distribution for carbon system is remarkable. |
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