The Bohai Sea is a semi-enclosed marginal sea in the North West Pacific. Meiofauna samples were collected from 22 stations in the Bohai Sea to document the spatial distribution, structure, and diversity of the meiofaunal community and investigate the major factors influencing the community features. A total of 20 higher taxa of meiofauna were identified. The dominant group was Nematoda, accounting for 90.8% of the total meiofaunal abundance on average, followed by Copepoda, Bivalvia, Polychaeta, Kinorhyncha, and Ostracoda. Meiofaunal abundance ranged from 121 ± 89 ind(10 cm2)-1 to 3042 ± 1054 ind(10 cm2)-1. Diversity indices also varied among different stations, with a Margalef's richness index(d) of 1.1–3.1, Shannon-Wiener diversity index(H′) of 0.7–1.8, and Pielou's evenness index(J′) of 0.4– 0.8. Meiofaunal abundance and diversity indices were significantly lower in the areas of Bohai Bay and adjacent to Laizhou Bay. The correlation analysis showed that meiofaunal abundance and diversity indices are closely linked to variations in sediment silt-clay content, medium grain size(MDΦ), and chlorophyll-a concentrations. The ecological quality status of most stations can be ranked from poor to moderate based on meiofaunal richness. According to the value of nematode to copepod ratio(Ne:Co ratio), most stations are uncontaminated, except seven stations are slightly or moderately contaminated. Both meiofaunal richness and Ne:Co ratio indicate the poor ecological quality of three stations adjacent to Laizhou Bay. The efficiency of the meiofauna communities as environmental indicators will be tested in a greater area in the future studies.
In this paper, we assessed the ecological and biodiversity status in the Bohai Sea through a quantitative survey on mac-rofaunal community at 25 stations in Laizhou Bay and adjacent waters in the autumn of 2006.We tested the robustness and effectiveness of taxonomic distinctness as an ecological indictor by analyzing its correlation with species richness and natural environmental variables and by analyzing other ecological indicators (Shannon-Wiener H' and W statistics from Abundance Biomass Comparison curve).Results so obtained indicated that the benthic environment of the study waters in general is not under major impact of anthropogenic disturbance, but some stations in Laizhou Bay and along the coast of the Shandong Peninsula and even in the central Bohai Sea might be moderately disturbed and showed signs of ecological degradation.The taxonomic distinctness measures △+ and Λ+ were independent of sampling effort and natural environment factors and were compliant to other ecological indicators.Further application of the taxonomic distinctness indicator to assess marine biodiversity and ecosystem health on a larger regional scale with historical data seems promising.
Meiofauna samples from intertidal sediments of Qingdao No.2 Bathing Beach, China, were collected for field study, and subjected to organic enrichment in a laboratory microcosm experiment for 21 d. There were three different treatments including non-organic addition as the control, low-organic enrichment (2 g DW green algae per 150 mL) and high-organic enrichment (10 g DW green algae per 150 mL). After 21 d, the meiofauna richness decreased in both organic enrichment treatments. Among the three treatments, total meiofauna abundance was significantly different, and the control groups had higher abundance than the other two treatment groups. However, the responses of the meiofauna abundance in the two organic enrichment treatments were non-significantly different. The relationship of meiofaunal abundance and nematode/copepod ratios to organic matter and oxygen level in the microcosm experiments were discussed.
WANG Jianing ZHOU Hong ZHANG Zhinan CONG Bingqing XU Shuhui
The whole metazoan community inhabiting Laizhou Bay and adjacent Bohai Sea waters were sampled in late autumn, 2006. Secondary production estimates for macrofauna and meiofauna were made separately. Total benthic secondary production was as high as 8.38 ±4.08 g ash-free dry weight （AFDW） m^-2 a^-1, which represented the autumn production level. In general, macrofaunal secondary production in Laizhou Bay was much lower than that in adjacent Bohai Sea areas. In contrast, meiofaunal secondary production in Laizhou Bay was higher than that in adjacent Bohai Sea areas. Macrofatma contributed 61% to benthic secondary production （5.09 ±3.26 g AFDW m^-2 a^-1）, lower than the value in previous studies in Bohai Sea. Sediment granulometric characteristics and bottom-water salinity could explain the substantial variability in the macrofauna biomass and production. Meiofaunal production was an important component of benthic production and exceeded macrofauna production under exceptional conditions, e.g. in Laizhou Bay, where macrofauna was restricted. Chlorophyll pigments （Chl-a） concentrations in sediment explained the general meiofaunal biomass and production distribution here.
