The Spatio-temporal Distributional Characteristics Of Meiobenthos And The Comparison With Five Years Ago In The Central Part Of Northern Yellow Sea

In this paper, we make use of the sediment samples collected in the central partof Northern Yellow Sea in June2011(summer cruise), November2011(autumncruise) and May2012(spring cruise), combined with various environmental factors,to carry out a statistical analysis and study on the group composition, abundance andbiomass of the meiofauna in the central part of northern Yellow Sea. By comparisonwith the previous908special survey data, we made a preliminary exploration on thelustrum change of meiofauna in the central part of Northern Yellow Sea.The results showed that, the sediments of the central part of Northern Yellow Seaconsist of clayey silt (YT), silty sand (TS) and sandy silt (ST), which have littleseasonal variations and a significant correlation among the characteristic parameters.The average organic carbon contents of the three cruises were (1.29±0.35)%in spring,(0.92±0.57)%in summer,(1.06±0.58)%in autumn, respectively, and has a highlysignificant negative correlation with the bottom temperature and the particle mediandiameter (MD). Average chrolophyll a contents of sediments for spring, summer andautumn were（0.77±0.34）g/kg（,0.27±0.14）g/kg（,0.62±0.19）g/kg, respectively。In all, we identified16meiofaunal groups, including Nematoda, Copepoda,Turbellaria, Cumacea, Hydrozoa, Halacaroidea, Polychaeta, Isopoda, Priapulida,Bivalvia, Amphipoda, Kinorhyncha, Gastrotricha and others. The group compositionvaried obviously with the seasons and the number of taxa is the most in summer,followed by spring, while inautumn is the least. Nematoda was the most dominanttaxon accounting for83.91%±8.69%of the total meiofauna and its dominance risingfrom spring to autumn; followed by copepods, accounting for4.23%±1.12%.The horizontal distribution of meiofauna took on a mosaic mode and presentedapparent seasonal characteristics. In coastal stations, the abundance and biomass of meiofauna were relatively high. In the vertical distribution, numerical percentages ofthe meiofauna distributed in the surface0-2cm, subsurface2-5cm and deep5-8cmsediments are73.20%±13.88%,17.88%±7.99%and8.92%±5.95%, respectively.Correlation analysis with environmental factors showed that water depth and Chl-awere the main factors influencing the sptiao-temporal pattern of meiofauna; In springand summer, the Northern Yellow Sea Cold Water Mass (NYSCWM) may have someimpacts on the distribution of meiofauna abundance and biomass，and NYSCWMrelated bottom water temperature and benthic primary production may becomedriving factors on the seasonality of meiofaunal horizontal distribution in the studyarea.There was no remarkable lustrum change in the general pattern of meiofaunaldistribution in the central part of Northern Yellow Sea albeit there were somedifferences in the number of meiofaunal taxa, abundance and biomass. In spring2012,the abundance and biomass of meiofauna were siginicantly lower as compared to thatof the908specieal survey five years ago.