| Jiadong Wang(Marine Biology)Directed by Profs.Yanli Lei and Kuidong XuMeiofaunal group composition,abundance,biomass and environmental parameters were investigated based on samples collected from 48 stations in the Yellow Sea(from 31°N to 39°N,120°E to 125°E) in June 2007.Mean abundance of meiofauna in the 48 sampling stations was 2194±1598 inds./10cm~2,with 3408±1578 inds./10cm~2 in the 17 sampling stations in the north Yellow Sea and 1529±1121 inds./10cm~2 in the other 31 sampling stations in the south Yellow Sea.Mean meiofaunal biomass of the 48 sampling stations was 1839±1289μ.g dwt/10cm~2,with 2760±1340μg dwt/10cm~2 in the north Yellow Sea stations and 1335±902μ.g dwt/10cm~2 in the south Yellow Sea stations.Among the 18 main meiofaunal groups sorted,free-living nematodes were the most abundant and contributed 88%to the total meiofaunal abundance,the percentage of nematodes of total meiofaunal abundance in the north Yellow Sea(87.7%) and the south Yellow Sea(88.3%) were similar. Nematodes contributed to 42%of the total biomass in the Yellow Sea,followed by polychaetes(22%),copepods(13%) and nauplii(12%).The investigation on the vertical distribution of meiofauna suggested that about 79%of the total meiofauna occurred in 0-2 cm depth in the Yellow Sea,17%in 2-5 cm depth,while only 4%in 5-8 cm depth.Statistical analyses showed that the abundance and biomass of total meiofauna were(markedly) significantly positively correlated to the concentrations of chlorophyll a and organic matter in the sediments and median diameter of sediments but significantly negatively correlated to the water depth,the biomass of total meiofauna was significantly negatively correlated to(silt and clay)%of the sediments.Meiofaunal group composition,abundance,biomass and environmental parameters obtained from 10 sampling stations in the Yellow Sea,East China Sea and South China Sea(from 17°N to 20°N,109°E to 112°E) were investigated from September to October in 2007.Mean abundance of meiofauna in the three sea areas was 2132±946 inds./10cm~2,1954±2047 inds./10cm~2 and 156±56 inds./10cm~2, respectively.Mean meiofaunal biomass in the three sea areas was 2193±1148μg dwt/10cm2,1865±1555μg dwt/10cm~2 and 212±22(μg dwt/10cm~2,respectively. Among the 14 main meiofaunal groups sorted,free-living nematodes were the most abundant and contributed 85%,89%and 85%,respectively,to the total meiofaunal abundance in the three sea areas.However,the biomass contribututed by dominant meiofaunal groups were different among the three sea areas.Nematodes contributed to 33%of the total biomass in the Yellow Sea,followed by polychaetes.In the East China Sea nematodes and polychaetes have the similar contributions(37%),while in the South China Sea polychaetes contributed to 56%of the total biomass.The investigation on the vertical distribution of meiofauna suggested that about 90%,46% and 63%,respectively,of the total meiofauna occurred in 0-2cm depth in the three sea areas.Statistical analyses showed that the abundances of total meiofauna and dominant groups were significantly positively correlated to the concentrations of chlorophyll a and phaeophytin a in the sediments and benthic water temperature but negatively correlated to the water depth.Our results were different from the study carried out in the 908-Cruise,where the abundances of total meiofauna and nematodes were only positively correlated to organic matter,indicating the sampling stations in 908-Cruise were more impacted by human activities than those of the present cruise.Meanwhile,a microcosm experiment was conducted to determine the effects of copper and lead(and mixture) heavy metals on meiofaunal groups,which were investigated on the day 1,3,7,14 and 21 after the heavy metals were incubated.The results showed that there was not obvious change on the abundance of nematodes in the treatments of high dose of Cu and the mixture of Cu and Pb treatments except on the 21st day.We suggest that at high dose levels the metals acted as preservatives such that nematodes died but were not decomposed.At the same sampling time,the abundance of nematodes in all treatments was higher than(or equal to) that in the control treatments,the abundance of nematodes in higher dose metals treatments was higher than that in lower dose treatments.Furthermore,the abundance of nematodes in low dose of mixture of Cu and Pb treatments was higher than that in low dose of Cu and low dose of Pb treatments.This is possibly due to the tolerance of some nematodes to metal pollution.
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