Preliminary Studies Of Mariculture Ecological Effects And Services Values In Shen’ao Bay

Shen’ao Bay is one of the most important mariculture bays in northeast Guangdongprovince, but also the famous oyster （Crassostrea gigas） cultivation and technologyand the sea demonstration bases. However, there has been severe environmentaldegradation and critical decline in aquaculture product quality and economic efficiencyin recent years, which should be attribute to the blind expandtion of farm scale and theunreasonable of aquaculture structure. Consequntly, the function of maricultureecosystem service was seriously affected. In order to study the mariculture ecologicaleffects and services values in Shen’ao Bay, Water environment was investigated inNovember2011, February, May and August2012. Environment and performance ofoyster on different distance gradient from cage fish farm were also conducted fromMarch to August2012. At the same time, the ecosystem services of Shen’ao Bay wereanalyzed and evaluated according to “Technical directives for marine ecological capitalassessment guide”(GB/T28058-2011).The result showed:1. Impact of cage fish farming on environment and Oyster in Shen’ao BayWater environment, particulate sediments and the performance of oyster ondifferent distance gradient from cage fish farm in the Shen’ao Bay was conducted fromMarch to August2012. The results showed that the concentration of inorganic nitrogen,inorganic phosphorus and POM of water within20m of cage area edge were higher thanthat of50m outside, The cage area water presents the lowest dissolved oxygen;particulate matter has shown that the deposition rate of particulate matter was higherwithin20m of cage area edge than that of50m outside, sediment organic matter, totalcarbon, total nitrogen, total phosphorus and organic matter percentage presented thefarther away from the cages farther, the lower the content. The organic matter, totalcarbon, total nitrogen, total phosphorus, and organic carbon deposition rate in cage area 0m were17.46,5.45,0.64,0.236and4.06g/(d.m2) respectively. The shells heightspecific growth rate of0.76%/d in cage area edge0m, was significantly higher than thatof50m outside (P <0.05), the wet weight specific growth rate within20m of cage areaedge was higher than50m outside, but not significant. In general, the impact of cagefish farm within20m on water environment, particulate matter and the performance ofoyster were greater than that of50m outside2. The effect of mariculture on water environment and water quality assessment inShen’ao BayThe anniversary changes of water environment, as well as the impact of differentfarming model of water quality were investigated in November2011, February, Mayand August2012in the way of laid13sampling sites in cage fish farm area, oyster-asparagus （Gracilaria lemaneiformis）poly-culture district and the control sites. at thesame time, use of potential water quality eutrophication and organic pollution index toevaluate water quality. The results showed that: the inorganic nitrogen concentrationwas the highest in winter (19.40μmol/L), the lowest in spring (5.13μmol/L), spring wassignificantly lower than the rest of the seasons, the annual average concentration ofNO3-N accounted for74%of the inorganic nitrogen. Inorganic phosphorusconcentration was the highest in summer (1.07μmol/L), the lowest in spring(0.38μmol/L), spring was significantly lower than summer and winter. Eutrophicationand organic pollution evaluation showed that the water quality was best in spring.Summer and winter were shallow in middle nutrition, organic pollution was4, presentsa middle organic pollution. The annual water quality nutritional status was oligotrophic,but presents mild organic pollution; The dissolved oxygen was the highest, whileinorganic nitrogen and inorganic phosphorus concentration were the lowest in oyster-asparagus poly-culture area compared to the cage fish farm area and control sites. Waterquality, nutritious and organic pollution evaluation show good, indicated that asparagusfarming can significantly improve dissolved oxygen and reduce the nutrient load ofwater. The temporal-spatial variations of water environment show that asparagus caneffectively improve the nutritional status of the water and play an important role inrepair of eutrophication sea area.3．Evaluation function of mariculture ecosystem service in Shen’ao BayThe ecosystem service of Shen’ao Bay were analysed and evaluated according to“Technical directives for marine ecological captail assessment”(GB/T28058-2011).The result showed that there were food provision, raw material provision, oxygenproduction, climate regulating, waste-cleaning and Scientific research in Shen’ao bayecosystem services.The total value of ecosystem services was79.59million yuan in2011,with an average unit value of ecosystem services5.98million yuan.km-2.Amongthe six services values, food provision value was49.76million yuan and accounted for62.52%of the whole ecosystem service value, which suggests food provision was thekey services of Shenao Bay. raw material provision was19.33million yuan, oxygenproduction was4.84million yuan, climate regulating was2.49million yuan andscientific research was2.14million yuan, waste-cleaning services was1.03millionyuan. Oyster and macroalgae production contributed79%of the total services value,indicated that oyster and macroalgae were of crucial significance in Shen’ao Baymariculture ecosystem services. Especially macroalgae farming was of significance inmaintaining and enhancing the ecosystem services in Shen’ao Bay.