Secondary Productivity Of Macrobenthos In Changli Nature Reserve

The structural stability and energy flow of marine ecosystem have always been the focus of scholars at home and abroad.Especially under the background of‘Carbon neutralization and carbon peak’,marine organisms have become the focus of scholars’research.As an important part of the marine ecosystem,the secondary productivity of macrobenthos can reflect the storage and flow of energy,and plays an important role in the stability of the ecosystem and the normalization monitoring of water quality and habitat environment.However,there were few reports on the relevant research in marine protected areas.In view of this,a marine ecological environment survey was carried out in the sea area of Changli Gold Coast National Nature Reserve in the spring and summer of2019-2021 to explore the relationship between the secondary productivity of macrobenthos and environmental factors,as well as the relationship between the carbon content of molluscs and secondary productivity.At the same time,based on the normal monitoring of the sea area of the reserve by the research group,the interannual changes of the secondary productivity of macrobenthos in the region from 2016 to 2021 were discussed.The results show that:（1）A total of 80 species（genera）were identified in 2019,91 species（genera）in 2020.The dominant species were Spio martinensis,Xenophthalmus pinnotheroides White and Branchiostoma belcheri tsingtauense.From 2019 to 2020,the proportion of species composition annelids in the study area increased,the number of species fluctuated significantly,and the species biomass and habitat density showed a downward trend.The diversity index showed that the habitat quality of the region was average in 2020 and poor in 2019 and 2021.Macrobenthos replaced frequently as a whole,and the community structure fluctuates rapidly.（2）From 2016 to 2021,the secondary productivity of Macrobenthos in the study area varied from 1.23 to 3.68[g（afdw）/（m²·a）].Secondary productivity mainly contributed to the transformation of biological groups from annelids to other organisms.The spatial distribution characteristics were that the high value points of secondary productivity gradually move towards the direction of Luan he River estuary from 2016 to 2019,and the high value pointed gradually move towards the area close to the bank in 2020 and 2021.Referring to the P/B mean value of each year,the succession of macrobenthos was 1.13～1.45 years per generation,indicating that Macrobenthos in this area have the characteristics of small individuals and fast reproduction.It was estimated that the productivity of the whole reserve from 2016 to 2021 was 1424.75～4262.67 t.The secondary productivity of macrobenthos was affected by environmental factors such as chlorophyll,median particle size,COD_Mnand active phosphate.（3）From 2016 to 2021,the carbon content of molluscs in the study area was 166.58～1204.90 T,calculated according to the amount of CO₂absorbed by molluscs in the study area in 2017,4175.46～4417.97,the economic value of marine carbon sink was about736755.57～779546.21 yuan（based on the average price of carbon emission trading pilot cities）,which was equivalent to the annual carbon sink of 63.36～67.04 ha natural forest land.There was a very significant strong correlation between secondary productivity and carbon content of molluscs（<0.01）.