Meiofauna Communities In Intertidal Zone Of Shenzhen Bay,Yundang Lagoon And Haimen Island

Ecological investigation has been conducted and meiofauna was collected from the intertidal zone of Shenzhen Bay in summer and autumn of 2015,and in intertidal zone of Yundang Lagoon and Haimen Island in summer and autumn of 2016.The group composition,abundance and distribution of meiofauna as well as the community structure and diversity of free-living nematodes were studied.Following are the main research achievements:(1)A total of 8 meiofaunal groups were identified,including free-living Nematoda,Copepoda,Polychaeta,Oligochaeta,Insecta,Bivalvia,Osracoda,Halacaroidea,Gastropoda and other unidentified taxa.Among them,free-living Nematoda was the most abundant taxa in all the three intertiidal zones.(2)The average abundance of meiofauna was 1290.99±326.09 ind.-10 cm-2 in intertidal zone of Shenzhen Bay,free-living Nematoda was occupying 98.73%of the total abundance.A total of 26 free-living nematode genera were identified in intertidal zone in Shenzhen Bay,belonging to 3 orders and 15 families.In summer,the percentage of feeding types of free-living nematodes was 2B>1B>1A>2A.In autumn,the percentage of feeding types of free-living nematodes was 1B>2B>1A>2A.The percentage of individuals greater than 5%in summer and autumn of 2015 was parodontophora,Terschellingia,Daptonema and Steineria,but the proportions were different in summer and autumn.Pearson correlation analysis showed that there was a significant positive correlation between free-living nematode abundance and sediment temperature in autumn.(3)The average abundance of meiofauna was 720.42±370.47 ind.-10 cm-2 in intertidal zone of Yundang Lagoon,free-living Nematoda was occupying 95.88%of the total abundance.A total of 30 genera belonging to 3 orders and 15 families of free-living nematodes were identified in intertidal zone of Yundang Lagoon.In summer,the percentage of feeding types of free-living nematodes was 2B>2A>1B>2A.The dominances greater than 5%in summer were Viscosia,Pomponema,Chromadorina,Terschellingia,Daptonema and Oncholaimus.In autumn,the percentage of feeding types of free-living nematodes was 1B>2B>1A>2A,and the percentage of individuals greater than 5%were Polysigma,Terschellingia,Paradesmodora and Pomponema.The Pearson correlation analysis showed that the genus number and richness index of free-living nematodes were significantly positively correlated with the sediment salinity,and the diversity index and dominance index were significantly positively correlated with the sediment salinity.(4)The distribution pattern of the abundance of meiofauna in summer is Kandelia obovata habitat>beach habitat.In autumn,there were Spartina alterniflora habitat>Kandelia obovata habitat>beach habitat.Pearson correlation analysis showed that the abundance of meiofauna and the abundance of free-living nematodes in beach habitat of Haimen Island were significantly positively correlated with the sediment temperature in summer.The abundance of meiofauna and the abundance of free-living nematodes in K.obovata habitat were significantly positively correlated with silt content.(5)A total of 58 genera,belonging to 23 families and 3 orders of free-living nematodes were identified in intertidal zone of Haimen Island.The dominant genus and feeding type of free-living nematodes differed in different habitats and different seasons,but 2A was the least abundant feeding type in all habitats and seasons.The free-living nematodes which percentage of individuals greater than 5%in the three habitats in summer and autumn were Terschellingia and Daptonema.Pearson correlation analysis showed that there was a significant negative correlation between free-living nematode genera and the sediment temperature in Kandelia obovata habitat in summer,and there was a significant negative correlation between the number of genus and the sediment salinity in beach habitat in autumn.(6)The ratio of free-living nematode to copepod showed that the mangrove area in three intertidal zones all suffering different degree pollution.The pollution degree was Shenzhen Bay>Yundang Lagoon>Haimen Island.The results of the maturity index(MI)showed that the environmental condition of the Shenzhen Bay was poor,the Yundang Lagoon was excellent,the beach habitat of Haimen Island was good,the Kandelia obovata habitat and Spartina alterniflora habitat was in moderate state.Comparing to the results of N/C ratio,the assessing results of MI were diferent in the Yundang Lagoon and the intertidal zone of Haimen Island.(7)Two suspicious new species of the genus Parodontophora were measured,photographed,plotted and described in detail in intertidal zone of Haimen Island.They were Parodontophora haimenensis sp.nov and Parodontophora communis sp.nov.respectively.