Shellfish provide an important environmental service by filtering a large amount of suspended organic matter,which could otherwise lead to the organic enrichment of sediments and the related impact.The impact of shellfish on the water column nutrient concentration(nitrogen,phosphorus)and dissolved carbon distribution was investigated during maturity and seedling period at a mussel farm (Mytilus edulis) of Gouqi Island.In order to understand the effect of mussel culture on water health and dissolved carbon pattern during the maturity and seedling periods,we studied the concentration of dissolved carbon,nitrogen and phosphorus on the spatial scales and the change in distribution pattern on time scales.The result illustrates that the concentrations of nitrogen and phosphorus in zones are higher than those in controls in maturity stage,in particular the nitrogen (P<0.05).The emissions and filter-feeding of mussel lead to the damage of the water health.On spatial scales,the distribution pattern of nitrogen,phosphorus in summer is contrary to the autumn.The water was purified by the emissions and filter-feeding of mussel.From the perspective of ecological effects,the concentrations of dissolved inorganic carbon in culture zone surface water are significantly lower than in control zones (P<0.05).Nitrogen-rich resulted in dissolved organic carbon in an unstable state.Therefore,from the perspective of dissolved organic carbon,the mussel culture was regarded as carbon source.Based on the above,mussel culture has a different effect on water health in maturity and seedling periods,and it needs further discussion about whether the mussel culture has carbon sink function or not.