Study On The Community Structure Of Meiobenthos And Classification Of Free-living Nematodes In The Intertidal Zone Of The Northern South China Sea

Undisturbed sediment samples were collected from the northern intertidal zone of the South China Sea in January and February 2019 and October 2020,respectively.Quantitative sampling of meiofauna was successfully conducted at 12 of these stations,and the abundance,biomass and production of meiofauna and their community diversity were analyzed in this area.Taxonomic studies of free-living nematodes were conducted,and a list of marine nematode species in the northern intertidal zone of the South China Sea was established.Studies have shown that the average abundance of meiofauna at 12 stations in the northern intertidal zone of the South China Sea is 1666±729 ind·10cm^-2,and the average biomass and production are 1395.4±514.5?gdwt·10cm^-2and 12558.7±4630.1?g·10cm^-2·a^-1,respectively.A total of 7 common meiofauna were selected from 12 stations,including free-living nematodes,polychaetes,copepods,etc..Among them,free-living nematodes are the most dominant group in the community,accounting for 93.9%of the total abundance of meiofauna,followed by polychaetes(2.4%),copepods(2.3%),turbellaria(0.9%),etc..In terms of biomass,free-living nematodes accounted for 44.8%of the total meiofaunal biomass.A total of 194 species(or taxa)of free-living marine nematodes belonging to 98 genera,35 families and 8 orders were identified in the sediment samples from 12 stations.The dominant species in the 12 stations were Terschellingia longicaudata de Man,1907?Microlaimus honestus De Man,1922?Steineria sinica Huang&Wu,2011 etc..Regarding feeding type,deposit feeders(1A+1B)were the most abundant both in terms of number of species(57.2%)and number of individuals(51.0%)were the most dominant.The meanfemale to male ratio in the marine nematode community was 1.9:1 and the mean juvenile percentage of the total number of individuals in the community was 31.7%.Six new species of marine nematodes were found and described in this study:Leptolaimus holovachovi Qiao,Jia&Huang,2020,Daptonema brevicaudatus Qiao&Huang,2020,Metadesmolaimus nanhaiensis sp.nov.,Perspiria longicaudatus sp.nov.,Ethmolaimus multispiralis sp.nov.?Dorylaimus zhangi sp.nov..Eight new records:Paraethmolaimus appendixocaudatus Jensen,1994,Theristus calx Wieser&Hopper,1967,Theristus metaflevensis Gerlach,1955.Pseudochromadora rossica Mordukhovich,Fadeeva,Semenchenko&Zograf,2015,Metalinhomoeus biformis Juario,1974,Spirinia parasitifera(Bastian,1865)Gerlach,1963,Leptolaimus gerlachi Murphy,1966,Leptolaimus luridus Timm,1963.