Ecological Monitoring And Assessment Based On Benthic Macrofauna In Xiamen Amphioxus Natural Reserve

Xiamen Amphioxus Natural Reserve was established in 1991 approved by the Xiamen municipal government,Xiamen Rare Marine Species National Nature Reserve was established in April 2000 officially approved by General Office of the State Council of the People’s Republic of China based on three natural reserves of amphioxus,egrets and Chinese white dolphins of a total area of 33088 ha.Since the establishment of Xiamen Amphioxus Natural Reserve,the amount of resource of amphioxus and the ecological environment of Xiamen Amphioxus Natural Reserve have been paid attention and monitored by the government and the scholars.Overall,the amount of resource of amphioxus in Huangcuo intertidal zone is poor,compared with the historical data,The amount of resources of amphioxus in Huangcuo subtidal zone decreased.Due to the differences of sampling stations,frequency and methods of the amphioxus and other benthic macrofauna,the ecological environment of the Amphioxus Natural Reserve can only be described qualitatively.This study conducted 6 voyages of sampling survey at Huangcuo and Nanxianshibaxian sea area of Xiamen Amphioxus Natural Reserve in summer of 2014(August in 2014),autumn(October in 2014),winter of 2015(January of 2015),spring(May of 2015),used different biotic index to evaluate the ecological environment of the Xiamen Amphioxus Natural Reserve(AMBI and M-AMBI index rarely used in the sandy sedimentary environment),Analyzed the relationship between environment factor and amphioxus population and benthic macrofauna community,compared the results of the two sampling methods of rake sampler and sediment sampler.The results can provide reference for the accurate management and protection of Xiamen Amphioxus Nature Reserve.The results are as follows:There were total 1458 ind.amphioxus in 6 voyages,in early,body length of amphioxus increased fast,later weight gain faster growth pattern.The seasonal variation of the density of the amphioxus in Huangcuo and Nanxianshibaxian sea area was autumn>summer>winter>spring.The seasonal variation of biomass was summer>autumn>winter>spring.The average density and biomass of amphioxus in the four seasons of Huangcuo sea area were higher than that of Nanxianshibaxian sea area.The average density and biomass of amphioxus were 34.30 ind./m2 and 1.81 g/m2,and the average density in Huangcuo sea area(35·87 ind./m2)was higher than that in Nanxianshibaxian sea area(32.74/m2),and the average biomass in Huangcuo sea area(1.94 g/m2)was higher than that in Nanxianshibaxian sea area(1.68 g/m2)too.(1)There were total 166 species of benthic macrofauna in 6 voyages,There were 67 species of polychaetes;followed by bivalves,42 species;followed by crustaceans,30 species;followed by gastropods,10 species;followed by echinoderms,5 species;followed by cnidarians,3 species;followed by the cephalochorda,2 species;other categories,including pycnogonids,nemertean,sipuncularia and fish,a total of 7 species.Total number of species,average density and average biomass of benthic macrofauna of four seasons of Huangcuo sea area were higher than that of Nanxianshibaxian sea area.(2)The ecological environment status of Xiamen Amphioxus Natural Reserve was assessed by using Shannon-Wiener species diversity index H’,Margalef species abundance index d,Pielous species evenness index J,Macrobenthic pollution index MPI,AMBI index and M-AMBI index.10 of the 12 evaluations of the macrobenthic pollution index MPI were severe distubance.The results showed that the evaluation results of diversity index H’,AMBI and M-AMBI were consistent,and their evaluation results showed that Xiamen Amphioxus Natural Reserve were in good condition from 2014 to 2016.(3)The density and biomass of amphioxus in Xiamen Amphioxus Natural Reserve were positively correlated with salinity.The average body length and body weight of amphioxus were not significantly correlated with salinity.The population parameter of amphioxus were not significantly correlated with temperature.The density,biomass,average body length and body weight of amphioxus were significantly positively correlated with gravel and sand content,and significantly negatively correlated with silt,clay content,average particle size and sorting coefficient.The evenness index J and the diversity index H’ of the benthic macrofauna were significantly negatively correlated with the salinity of the seawater.The species number,the evenness index J and the diversity index H’ of the benthic macrofauna were significantly negatively correlated with gravel and sand content,and significantly positively correlated with silt,clay content,average particle size and sorting coefficient.The species density,biomass,evenness index J,richness index d and diversity index H’of benthic macrofauna were all significantly positively correlated with the average particle size and sorting coefficient.It can be concluded that the higher content of silt and clay,the smaller density and biomass of amphioxus.(4)Five populations parameters of amphioxus of two sea area by different sampling methods in the summer of 2015 and the summer of 2016 were compared,the results showed that the individual number,density,biomass,average body length and average body weight of rake sampler were higher than the sediment sampler.Three community parameter of benthic macrofauna of two sea area by different sampling methods in the summer of 2015 and the summer of 2016 were compared,the results showed that the number of species,density and biomass of the benthic macrofauna of rake sampler were higher than the sediment sampler.One-Way ANOVA analysis showed that the number of species of benthic macrofauna obtained by the two sampling methods was significantly different,and the density and biomass of benthic macrofauna obtained by the two sampling methods were not significantly different.