北部湾冬季潮间带小型底栖动物群落结构和自由生活海洋线虫多样性研究

Study on the Community Structure of Meiofauna and the Diversity of Free-Living Marine Nematodes in the Intertidal Zone of Beibu Gulf in Winter

2019年2月,采集了北部湾潮间带5个站位沉积物样品,对该区域小型底栖动物的丰度、生物量和生产量进行了分析,对自由生活线虫进行了分类研究。结果表明,北部湾潮间带5个站位共发现自由生活线虫、桡足类、多毛类等7个小型底栖动物类群,小型底栖动物的平均丰度为2352±936 ind·10 cm^(-2),平均生物量和生产量分别为2075.6±528.9μg dwt·10 cm^(-2)和21165.0±7478.0μg dwt·10 cm^(-2)·a^(-1)。小型底栖动物主要分布在沉积物0~2 cm的表层,平均丰度为1706 ind·10 cm^(-2),占总丰度的72.5%。5个站位自由生活线虫平均丰度为2195±843 ind·10 cm^(-2),占小型底栖动物平均丰度的93.3%。关于自由生活线虫的摄食类型,刮食者或硅藻捕食者(2A型)占比最多,其次为选择性沉积食性者(1A型)、非选择性沉积食性者(1B型)和捕食者或杂食者(2B型)。5个站位线虫群落中雌雄比例平均为1.2∶1,幼体占线虫群落个体总数的平均值为35.4%,成熟个体远多于幼体,说明取样时并非线虫主要的繁殖季节。5个站位共鉴定出自由生活海洋线虫120种,隶属于76个属,34科,8目,主要优势种为Terschellingia longicaudata de Man,1907、Ptycholaimellus ocellatus Huang&Wang,2011、Pseudochromadora rossica Mordukhovich,Fadeeva,Semenchenko&Zograf,2015等。物种丰富度指数为3.192~7.535,均匀度指数介于0.5206~0.8206之间,香农-威纳多样性指数为1.894~2.844,该海区自由生活线虫群落的多样性低于南海东北部(3.97~4.551)。

In February 2019,sediment samples were successfully collected from five stations in the intertidal zone of Beibu Gulf,and the abundance,biomass and production of meiofauna in the region were analyzed,and the taxonomic study of free-living nematodes was conducted.The results showed that a total of 7 meiofauna groups,including free-living nematodes,copepods,and polychaetes,were found at 5 stations in the Beibu Gulf intertidal zone.The mean abundance of meiofauna at the five stations in the intertidal zone of Beibu Gulf were 2352±936 ind·10 cm^(-2),and the mean biomass and production were 2075.6±528.9μg dwt·10 cm^(-2)and 21165.0±7478.0μg dwt·10 cm^(-2)·a^(-1),respectively.Meiofauna are mainly distributed in the surface layer of sediments 0~2 cm,with an average abundance of 1706 ind·10 cm^(-2),accounting for 72.5%of the total abundance.The mean abundance of free-living nematodes at the five stations was 2195±843 ind·10 cm^(-2),accounting for 93.3%of the mean abundance of meiofauna.Regarding the feeding types of free-living nematodes,scrapers or diatom predators(2A)accounted for the largest proportion,followed by selective sediment feeders(1A),non-selective sediment feeders(1B)and predators or omnivores(2B).The average larvae accounted for 35.4%of the total number of individuals in the nematode community.There were far more mature individuals than larvae,indicating that sampling was not the main breeding season for nematodes.A total of 120 species of free-living marine nematodes were identified in 5 stations,belonging to 76 genera,34 families,and 8 orders.The main dominant species are Terschellingia longicaudata de Man,1907,Ptycholaimellus ocellatus Huang&Wang,2011,Pseudochromadora rossica Mordukhovich,Fadeeva,Semenchenko&Zograf,2015,etc.Margalef’s species richness index ranges from 3.192 to 7.535.Pielou's evenness index ranges from 0.5206 to 0.8206,and the Shannon-Weiner diversity index ranges from 1.894 to 2.844.The diversity of free-living nematode communities in this sea area was lower than that in the northeastern South China Sea(3.97 to 4.551).