| This paper is based on the research about the macrobenthos community structure and function groups in the silt-arrester dams,east bay of Nanhui District,Shanghai.By collecting data of macrobenthos in the tidal flat aims to support the research about the influence and restoration projects of the reclamation area's ecology system.What's more,To have a survey about Environmental factors on zooplankton and macrobenthos about the restoration project in Jinsha Bay,which rely on the release of macrobenthic fauna to restore the ecology system,to support the restoration in east bay of Nanhui.1.The effect of the reclamation on macrobenthosThe research had compared the macrobenthos in the natural area with the reclamation area from April of 2015 to December of 2016.and collected data from both the silt arrester and the natural area.Each area has two sample points,S1 and S2 for the former,N1 and N2 for the latter.The research in 2015 had collected 33 genera and 37 species of macrobenthos in Nanhui east shoal,which includes 10 genera and 12 species of Mollusca,16 genera and 18 species of Arthropod,5 genera and 5 species of Annelida and others 2 genera,2 species.The number of species in the natural beach is 28>the number in the silt-arrester area which is 25.The dominant species in the natural area were Helice tientsinensis,Ilyoplax deschampsi,Neoeriocheir leptognathus,Potamocorbula amurensis,Stenothyra glabar,Assiminea latericea,Assiminea latericea and so on.While the dominant species in the silt-arrester area were Chironomid larvae,Assiminea sp.,Assiminea violacea,Ilyoplax deschampsi,Helice tientsinensis,Corbiculafluminea and so on.The research in 2015 showed that the annual abundance distribution:S2(129.67ind./m2)>S1(80.33ind./m2)>N1(52.33ind./m2)>N2(23.00ind./m2).The annual average species' spatial distribution showed that:S2(25.42g/m2)>N1(20.59g/m2)>N2(13.85g/m2)>S1(2.22g/m2).The research in 2016 showed that the annual abundance distribution:S2(189.00ind./m2)>S1(165.00ind./m2)>N1(125.00ind./m2)>N2(119.00ind./m2).The annual average species' spatial distribution showed that:N1(122.22g/m2)>N2(68.07g/m2)>S2(56.00g/m2)>S1(52.146g/m2).The annual average Shannon-Wiener diversity index of the macrobenthos were listed in the order:natural beach>silt-arrester area.The cluster and MDS analysis came to a conclusion that there was a significant difference in the structure of benthic community between the silt-arrester and the natural area.What's more,the ABC proved that macrobenthos' living condition had been seriously interfered in the silt-arrester areas,while there was no significant disturbance in natural areas.Comparing the historical data of macrobenthic fauna in 2004 and 2009,the habitat health assessment showed that the value of A+has a significant deviation from the theoretical average.At the same time,the value of ?+close to the lower limit of the confidence interval.Considering all those factors,indicated that the classification of macrobenthic fauna is relatively concentrated,and the habitat may be disturbed by the human factors and deviate from the average level of the Yangtze River estuary.2.The spatial and temporal distribution of the macrobenthos' functional group in both the outside and the inside of the reclamation in the east beach of NanhuiThere were five kinds of functional groups founded in the east beach of Nanhui includes 5 kinds of PI;6 kinds of Ph;one kind of C,O and D.The abundance list of the silt-arrester area is Ph>PI>O>C>D,from big to small.The biomass of PI is bigger than Ph.The abundance list of the natural beach is PI>Ph>O>C>D,from big to small.The two-factor analysis of variance showed that the Margalef richness index of O in the sampling point had a very significant difference(F=13.78,P<0.01).The Pielou evenness index of PI showed significant under the seasonal factor(F=6.35,P<0.05).The Pielou evenness index of Ph showed significant under the sampling point(F=0.31,P<0.05).The Pielou evenness index of O showed significant under the sampling point(F=6.36,P<0.05).The Shannon-Weiner index of omnivores showed significant under the sampling point(F-5.86,P<0.05).Others showed no significant difference under the factor of season or sample point(P>0.05).The above results indicated that the composition of macrobenthic fauna was related to the habitat heterogeneity of natural tidal flat and silt-arrester area.Different functional groups of macrobenthos change with seasonal and regional interactions.The complete reclamation will lead to a single species of benthic functional groups.3.Evaluation of ecological restoration by the macrobenthosDuring the investigations in the beach of Jinsha bay,10 kinds of macrobenthos which includes Annelida(2)?Mollusca(5)and Crustacea(3)were found.Among them,Potamocorbula laevis and Eachisina sp.appeared the highest frequency.The density of benthic fauna is between 373.33ind./m2 and 1237.33ind./m2.Seasonal density showed that May>November>August>July.The biomass of benthic fauna is between 92.11g/m2 and 1067.34g/m2.Seasonal biomass showed that November>May>August>July.The diversity of benthic fauna showed different in different months.The cluster analysis from the 10 sampling point and MDS sorting results were basically consistent.There were 18 species of zooplankton and 7 species of floating larvae,including Copepoda(9),Pelagic larvae(7),jelly fish(5)and 4 other species.The abundance and biomass of the Zooplankton varied in different seasons and samples.By using the CCA graph to analyze the relationship among environment factor,zooplankton and macrobenthos showed that zooplankton was affected by Wt,DO,SD,sal,pH and water color.The macrobenthos were affected by SD,Wt,DH,Sal and DO.And pH is a key factor affecting zooplankton and macrobenthos.By using the diversity index of zoooplankton to evaluated the water quality of Jinsha bay showed that the index of d was 2.31 in the purifying reclamation area and 2.33 in the natural area in November.While making contrast with the normal reclamation area,d was 0.77.The water pollution in the natural area and purifying reclamation area were lower,while reclamation area was serious.The index of H' was 2.91 in the purifying reclamation area and 2.30 in the natural area while 0.92 in the normal reclamation area in November.The water pollution was ?-medium in the natural area and purifying reclamation area while the reclamation area was serious.The water pollution in May was serious while turned to medium in July and August.The cluster and MDS analysis showed that the biomes structure of the purification area,reclamation area and natural area were different.In the reclamation area the temperature had a significant impact on the community structure of zooplankton and macrobenthic fauna.Through the release of macrobenthic fauna to restore the ecology system,the water quality in the purificating reclamation area and natural area is almost the same.While the pollution in the reclamation area is serious.Therefore,the method by releasing macrobenthos to restore the water quality in the reclamation area works. |
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