The Study Of Meiofauna Ecology And Nematode Community Structure In The Intertidal Zone Of Qingdao Bay

Meiofauna was investigated in the intertidal zone of Qingdao Bay. Meiobenthoswere sampled with the two cross-section of the Qingdao Bay intertidal zonebimonthly from December2010to October2011. The sedimentary environment ofdifferent months, the abundance and biomass of meiobenthos, and the relationshipbetween meiobenthos and environment were quantitatively studied during the periodsof investigation. Furthermore, the species composition and biodiversity of free-livingmarine nematodes, the dominant taxa, were analysed by identified. The purpose of thestudy is to provide the basic data for further study of the intertidal benthic ecology,based on the detailed survey data of the meiobenthos of intertidal zone in Qingdaobay.The results showed that, the changing trend of the bottom temperature in yearswas August＞October＞June＞April＞December＞February. The changes of salinitywere basically similar with the annual changes of bottom temperature, yet there wasno obvious change of pH anniversary. The sediment type of Qingdao bay was mudand sand. Silt content was the highest, with the average content of60.51%, followedby clay content （24.58%）, sand content was the lowest （14.91%）. The MDΦ of thesediment was in the range of2.85^-0.06; QDφ was in the range of1.62⁰.39, SKφwas in the range of0.25^-0.38. The sand content decreased, and the silt and claycontent increased from high tide to low tide. The average content of organic carbon（TOC） in sediments was0.52%, the highest in October （0.73%）, the lowest in April（0.42%）, and from April, the organic carbon content showed a trend of increase. Theorganic carbon was mainly concentrated in the depth of5⁸cm （0.55%⁰.69%）, andon the surface （0²cm）. There was less （0.24⁰.53%） organic carbon. The organiccarbon content was no significant difference with annual change, and was significant difference at different tide zone.The average content of chlorophyll a in the sediment was5.10mg/kg. The highvalue appeared in April （5.90mg/kg）, and the lowest value appeared in June （4.78mg/kg）. The chlorophyll a content was no significant difference with annual change,and was significant difference at different tide zone, also. Besides, the content ofchlorophyll a was positively correlated with MDΦ, and negatively correlated with pH.A total of five groups of meiofauna were identified in the intertidal zone ofQingdao Bay. They were Nematoda, Copepod, Ostracoda, Bivalvia and otherunidentified meiofauna. The free-living marine nomatode was the most dominantgroup, whose abundance was up to2493.8ind.·10cm^-2, accounting for97.9%of thetotal abundance of meiofauna; with Copepod being the second, whose abundance onlywas42.3ind.·10cm^-2, according for1.7%of the total abundance. Besides, the groupcomposition was no significant difference in years, and was significant difference atdifferent tide zone. The average abundance of meiofauna was2546.4ind.·10cm^-2intotal, and respectively2545.6ind.·10cm^-2and2547.2ind.·10cm^-2on A and Bsections. The mean biomass of meiofauna was1265.3μg.dwt·10cm^-2, and the meanproduction of meiofauna was11387.5μg.dwt·10cm^-2.a^-1.The top0²cm had the most meiofauna compared to other layers in Qingdao bay.The percent of meiofauna distributed in the5⁸cm,2⁵cm and0²cm were9.02%,19.09%and71.88%respectively. Most of meiofauna concentrated in the top0²cm,and decreased with the depth down. Both the Nematode and Copepods were the samewith meiofauna. In addition, meiofauna had no a seasonal vertical migration withdepth in the sediments in Qingdao Bay.The combination of TOC and QDφ could explained the distribution pattern ofmeiofauna in Qingdao Bay by the analysis of BIOENV, and the coefficient was0.629.A total of30species of nematodes were identified on the A section, and thedominant species were Oncholaimus sp.1，Metadesmolaimus sp.1，Daptonema sp.2，Daptonema sp.3，Neochromadora sp.2and Oncholaimus sp.2. Besides, there weredifferent species composition of nematode in different tide zone and different depth. The average values of Shannon-Wiener index（H’）, evenness index（J’） and richnessindex（d）were2.833、0.698and2.832respectively. In addition, the highest values ofthese indexes appeared in the low tidal region, and the lowest values appeared in thehigh tidal region, which showed that the organic matter pollution improved from highto low tidal region.