| Based on the survey results of macrobenthos,kangaroos and sediments along Yanpu Bay in May 2018(spring)and October 2018(autumn),this paper investigates the characteristics of macrobenthos community,Kandelia candel growth and sediment quality and conducted a preliminary study on the mechanism of the impact between macrobenthos,Kandelia candel and sediments.A total of 21 species of macrobenthos were investigated in spring,among which the number of gastropods was the largest;20 species were investigated in autumn,among which the number of bivalves was the largest.There were two dominant species in spring and three dominant species in autumn.Cerithidea largillierti and Metaplax longipes are common dominant species in two seasons.The density and biomass of macrobenthos in spring were generally greater than in autumn.In general,the Shannon-Wiener diversity index(H')and evenness index(J')of species diversity in autumn were highter than those in spring,and the richness index(D)in spring was highter than autumn.Species diversity and ABC curve results showed that the macrobenthos communities in spring and autumn were moderately disturbed.According to the niche breadth values of the major species of macrobenthos,they were divided into broad-niche species(B_i>2.0),mid-niche species(1.1<B_i?2.0),and narrow-niche species(0<Bi?1.1);the niche overlap values of large benthic animals in spring and autumn were significant(>0.6)have only one species pair.The results of community structure analysis showed that the similarity between macrobenthos communities in spring was higher than that in autumn,and that Cerithidea largillierti,Lunatica gilva,and Metaplax longipes were not only the typical characteristic species of community structure similarity,but also the main divergent species of community structure difference.The range of Kandelia candel height in spring was 16.40~94.78cm,the average plant height was 46.63cm;the base diameter range was 0.40~4.00cm,the average base diameter was 1.56cm;the order of the total biomass was quadrat C>quadrat B>quadrat D>quadrat E>quadrat A.The range of Kandelia candel plant height in autumn was 22.50~87.00cm,the average plant height was 51.20cm;the base diameter range was 0.70~5.40cm,the average base diameter was 2.56cm;the order of the total biomass size was quadrat C>quadrat D>quadrat B>quadrat A>quadrat E.In spring and autumn,the sediment quality was good,only the content of copper exceeded the first class standard,which conforms to the second class standard,and the content of other environmental factors conforms to the first class standard.The results showed that the order of pollution degree of heavy metals in spring was Cr<Cd<Hg<Pb<Zn<As<Cu,and that in autumn was Cr<Cd<Pb<Zn<Hg<As<Cu.In spring and autumn,the order of potential ecological damage coefficient of heavy metals was Hg>Cd>As>Pb>Cu>Cr>Zn.Studies on the relationship between macrobenthos and sediments showed that organic carbon,Cd,Pb,and Zn were the main factors affecting the distribution of macrobenthos in spring;Cd,Pb,Zn,Cr,and Cu were the main factors affecting the distribution of macrobenthos in autumn.The research on the relationship between macrobenthos and the growth of Kandelia candel showed that the density growth rate of macrobenthos in quadrat D was the largest,and the growth rate of the height and total biomass of cannabis was also the largest,but its biomass had decreased.The growth rate was lower and the biomass was reduced the most in quadrat A,but the growth rate of cane plant height and total biomass was second only to the quadrant D.The research on the relationship between Kandelia candel and sediment showed that the changes in the content of heavy metals were more complicated,while the plant height and biomass of Kandelia candel increased overall. |
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