The water and sediment discharge regulation (WSDR) project, which has been performed since 2002 before flood season every year, has become one of the most effective measures to maintain the healthy state of Huanghe River. Macrobenthic community patterns, such as species composition, dominant species, spatial pattern of biomass and abundance were analyzed based on the investigation data of macrobenthos collected in mid-June (before WSDR) , early July (during WSDR) and mid-July (after WSDR) - In the investigated area, 119°05' - 119°27'E, 37°44. 5' -38°00'N, 13 sample stations were set up. A total number of 100 species were identified from the samples, in which 38 species are members of Polychaete, 41 of Mollusca, 15 of Crustacea, 3 of Echinodem and 3 of other groups. Polychaete and Mollusca were dominant both in biomass and abundance in the Huanghe estuary in summer. Dominant species, defined as with index of relative importance (IRI) value more than 500, were Polychaete or Mollusca in all 3 surveys. The distribution of biomass and abundance of macrobenthos had significant difference both in time scale and spatial scale. The diversity index such as Margalef richness index (D) , Shannon-Wiener diversity index (H'~ and Pielou' s evenness index (/') were used for studying the diversity of macrobenthic community. The D, H' and J' of community in survey before WSDR were close to that during WSDR. The D was lower in survey after WSDR than that in survey before WSDR and during WSDR. The H' and J' were higher in survey after WSDR than that in survey before WSDR and during WSDR. A higher proportion of Polychaetes and lower proportion of Echinoderms meant that the macrobenthic community might be under serious environmental pollution. The results of diversity classification showed that the Shannon-Wiener diversity index were poor in all 3 surveys. And the Margalef richness index was poor in survey before WSDR. The Margalef richness index was medium in surveys during and after WSDR. The biomass of Echinoderms declined substantially compared with the historical surveys.%根据2011年6月中旬(前调查)、7月上旬(中调查)和7月中旬(后调查)黄河口海域3航次大型底栖生物调查资料,对该海域大型底栖动物群落结构及多样性进行了研究.结果表明,3次调查共获得大型底栖动物100种,其中多毛类和软体动物种类数占79.0％,棘皮动物仅占3.0％.调查期间黄河口海域多毛类和软体动物在生物量和栖息密度上均占有优势地位,3次调查优势种均为中小型的软体动物和小型多毛类动物.3次调查大型底栖动物生物量和栖息密度的分布在时间和空间尺度上均出现较大变化.前调查和中调查,调查海域大型底栖动物的丰富度指数(D)、多样性指数(H')、均匀度指数(J')接近；而后调查与前调查、中调查相比,丰富度指数更低,而多样性指数和均匀度指数更高.群落中多毛类比例较高而棘皮动物比例较低,表明黄河口海域底栖生物群落处于较为严重的环境污染状态.多样性分级结果表明,3次调查多样性指数均为差级,后调查丰富度指数为差级,前调查、中调查丰富度指数虽为中等,但非常接近差级.与历史资料相比,棘皮动物生物量已经大幅下降.
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