Studies On Meiofauna Ecology And Taxonomy Of Free-living Nematodes From Northeast Of The South China Sea

Meiobenthos were sampled in seven stations in the northeastern part of the South China Sea in August 2017.Three small benthic groups,i.e.,Nematode,Copepod and Polychaete,were selected in the seven stations.Results show that the average abundance and biomass of meiobenthos of small benthic animals were(224.3±52)ind·10cm^-2and(54.8±40.56)?g·10cm^-2.Among which,free-living nematodes were the dominant group with the abundance of 95.7%,followed by copepods(4.1%)and polychaetes(0.2%).The average individual dry mass of nematode was 0.15?g.The biomass of Nematode was(32.2±12.96)ind/10cm²,accounting for 58.7%.About 65.7%of the meiofauna,including dominant nematodes(64.8%),were found in the top 0?2cm sediment.In total,293 species were identified,belonging to 105 genera,26 families,and 4 orders,including 2new species and 5 new records.The major dominant genera were Acantholaimus Allgén1933?Halalaimus de Man 1888?Cervonema Wieser 1954?Daptonema Cobb 1920?Thalassomonhystera Jacobs 1987?Sabatieria Rouville 1903 and Molgolaimus Ditlevsen1921?.In feeding type,the deposit feeders(1A+1B)were the dominants(70.3%of species and 72%of individuals).The average ratio of males to females was 1?0.45,and the young individuals accounted for 32.5%of the total population of nematodes.Among the identified 293 species of free-living nematodes,published two new specie:Elzalia heterospiculata Jia&Huang 2019 and Wieseria bicepes Jia&Huang 2019,discovered and described eight new records:Cricohalalaimus vagabundus Bussau 1933;Trefusia attenuata Bussau 1993;Paramphimonhystrella barbula Leduc 2014;Amphimonhystera molloyensis Tchesunov&Mokievsky 2005;Amphimonhystrella bullacauda Tchesunov&Miljutina 2005;Letolaimus tertius Holovachov&Bostr?m2013;Metadasynemella macrophalla De Coninck 1942;Manganonema microcephalum Bussau 1933.