Evaluation Of Ecological Effect Of Artificial Reef And Ecological Carrying Capacity Of Mainly Species Stock Enhancement

Under the multiple pressures of global environmental changes and human activities,the environment of local sea areas has deteriorated,and the decline of offshore biological resources has become more and more serious.Therefore,our country has accelerated the construction of artificial reefs and stock enhancement activities,in order to achieve the purpose of repairing the damaged ecosystem environment and increasing biological resources through the construction of marine ranches.From 2015 to 2020,my country has established six batches of national marine ranch demonstration areas,and currently 136 national marine ranch demonstration areas have been approved for construction.Although the ever-expanding marine ranches have achieved significant economic and social benefits,few studies on the evaluation of the ecological environment effect of the marine ranch and the assessment of the capacity of stock enhancement species.The sustainable development of marine ranches requires basic theory and technical support.In this paper,the first batch of national marine ranch demonstration area in the Western sea area of Furong Island,is taken as an example.The difference in water environment parameters between Furong Island fish reef area and non-fish reef area was analyzed,and Furong Island artificial reef Ecopath model was established to evaluate the ecological capacity of Sebastes schlegeli and Portunus trituberculatus in this paper.Analytic hierarchy process and the comprehensive index method was used to evaluate the ecological health level of the fish reef area.The main research results of this paper are as follows:1.The water temperature,dissolved oxygen,salinity,p H and other hydrological environmental parameters of the artificial reef area of Furong Island and the control area were compared and analyzed,it was found that all hydrological environmental parameters had significant seasonal differences(P<0.05).In winter,the dissolved oxygen in the reef area was significantly higher than that in the non-fish reef area(P<0.05).The p H value of fish reef areas in spring and autumn was significantly higher than that in non-fish reef areas(P<0.05).The fish reef area has better ecological conditions,and the growth and reproduction of plankton are used to cause the p H of the water to rise.The nitrogen nutrient content of the fish reef area was significantly lower than that of the control area(P<0.05),and the nitrogen nutrient content of different seasons was extremely different(P<0.01).The average COD concentration in fish reef areas was 2.12±1.21 mg/L,and the average COD concentration in non-fish reef areas was 1.90±0.92 mg/L.The difference in COD concentration between fish reef areas and non-fish reef areas in winter was extremely significant(P<0.01).The COD concentration in the fish reef area reached the highest in winter,with a concentration of 3.53±0.77 mg/L;the COD concentration in the fish reef area and non-fish reef area in winter was significantly higher than that in autumn,indicating that the organic pollution of the water ecosystem in winter has increased.There are 31species of fishery resources in the reef area,which is more than that in the control area;the biomass of fishery resources in the reef area is 2.15 times that of the control area,and crabs are the first dominant species in the reef area and the control area.The Shannon-wiener index,pielou index between stations,and simpson index in the fish reef area were significantly higher than those in the control area,indicating that the construction of artificial reefs is beneficial to the enhancement of fishery resources and the restoration of water ecosystem functions.2.Based on Ecopath analysis of the trophic level structure and energy flow characteristics of the artificial fish reef area of Furong Island,the trophic level of the artificial reef ecosystem is between 1-3.974,and the lowest trophic level is phytoplankton and detritus.The highest trophic level is Lateolabrax japonicus functional group,and the trophic level is 3.974.The average conversion efficiency between the trophic levels of the grazing food chain is 9.871%,while the average conversion efficiency between the trophic levels of the detrital food chain is 10.96%,and the total system conversion efficiency is 10.23%,which is slightly higher than that of Lindeman efficienvy(10%).Connectance index is 0.299,system omnivory index is 0.16,finn’s cycling index is 5.83,and the finn’s mean path length is 2.655,indicating that the energy of the system is not fully utilized,and there is a case of energy transmission blocking.3.According to the Ecopath model,the ecological capacities of Sebastes schlegeli and Portunus trituberculatus are 0.129t/km~2and 4.72t/km~2,respectively,which are 1.54 and 3.69 times the existing biomass.After reaching the ecological capacity,there is no significant difference in the overall characteristic parameters of the ecological system in the artificial reef area of Furong Island.The biomass of Sebastes schlegeli and Portunus trituberculatus increased to ecological capacity,and there was no significant impact on the stability and maturity of the ecosystem of the artificial reef area of Furong Island.The biomass of the stock enhancement of Sebastes schlegeli is 0.0882 t/km~2.Assuming that the weight of Sebastes schlegeli is70g/tail,the artificial reef area in the western sea area of Furong Island is 160,000 mu(about 106.67km~2).The number of breeding and releasing tails of Sebastes schlegeli was 134,400 tail.4.Analytic hierarchy process and comprehensive index method were used to evaluate the health level of Furong Island fish reef area,select three types of evaluation indicators:water environment factor,community structure factor and ecosystem structure function factor,and determine the weight value of the indicator through pairwise comparison of the evaluation indicators.Finally,the four-quarter ecosystem health index of the fish reef area and the control area was obtained.The results showed that the ecosystems in the fish reef area of Furong Island and the control area were in a relatively healthy state.The ecosystem health index of the fish reef area in the fourth quarter averaged 0.7075±0.046,and that of the non-fish reef area was 0.6785±0.048.The ecosystem health of fish reef areas is better than that of non-fish reef areas.The seasonal comparison of ecosystem health index is summer(EHI=0.743)>autumn(EHI=0.704)>spring(EHI=0.696)>winter(EHI=0.630).