The Assessment Of Benthic Community Health And Habitat Suitability In The Huanghe (Yellow River) Estuary And Its Adjacent Areas

The macroinvertebrate communities have rapidly respond to various natural and human-induced stresses, thus take advantage of the relations between macrobenthos and environment disturbance to indicate the environmental quality status. Biotic indices, based on benthic community, have been an important tool in the health assessment of marine ecosystem. Benthic habitats are important environmental factor to macrobenthos communities composition and spatial distribution. The suitability of benthic habitats has an influence on benthic community health.This paper based on the dataset of the eighteen cruises in May and August from 2004 to 2013, using three biotic indices, the Shannon-Wiener Index (H1), the AMBI (AZTI’s Marine Biotic Index) and the M-AMBI (multivariate AMBI), to assess the benthic community health in the Huanghe (Yellow River) estuary and its adjacent areas. The applicability of benthic habitat quality of the three biotic indices in the study areas was compared, and the benthic habitat suitability was assessed. And compared with water environment and sediment environment elements of benthic habitat, the assessment of benthic habitat suitability was conducted.The results showed that a total of 203 macrobenthos were collected in the eighteen cruises, including Polychaetes, Mollusks, Crustaceans, Echinodermata, Nemertea, Echiura, platyhelminthes, cnidaria and Hemichordata, which belong to nine phyla. The macrobenthos were dominated by polychaetes, which accounted for 38.4% of the total species. Followed by mollusks and crustaceans, which respectively accounted for 28.6% and 24.1% of the total species. The total species abundance of six cruises with range from 1996 ind./m2 to 8672 ind./m2. The total species abundance of May in 2004,2009,2011,2013 and August in 2004,2010 were obvious higher than that of other cruises in the Huanghe estuary and its adjacent areas. And the ecological groups (EGs) of macrobenthos were dominated by EGI, EGⅡ and EGⅢ with respectively accounted for 31.5%,36.0% and 21.2%, which respectively represent species very sensitive to environmental disturbance, species indifferent to enrichment environmental disturbance and species tolerant to environmental disturbance.The H’mean values of the eighteen cruises ranged from 1.67 to 3.04. Only the cruise in August 2010 was in a ’High’ ecological quality status (EQS).77.8% of the cruises (fourteen cruises) were in’Good’EQS.16.7% of the cruises (other three cruises) were in’Moderate’EQS. In the survey, the sites close to the estuary with a ’Moderate’EQS, sites 3,6 and 9, suffered heavier disturbance than others with a ’Good’or’High’EQS. The AMBI mean values of the eighteen cruises ranged from 1.29 to 2.94. All the eighteen cruises were in’Good’EQS. In the eleven sites of spatial distribution, though all the sites were also in’Good’EQS, the EQS of sites 3, 6,9 and 10 were worse than others. The M-AMBI mean values ranged from 0.38 to 0.68.38.9% of the cruises (seven cruises) were in’Good’EQS. Only one cruise, August 2013, was in a’poor’EQS.55.6% of the cruises (other ten cruises) were in ’Moderate’EQS. In the eleven sites, the inshore sites,2,3,6,9 and 10, suffered heavier disturbance with a’Moderate’or’Poor’EQS. Others were in’Good’EQS. The result showed that the evaluation results of the three indices were significant different. The ecological quality status (EQS) levels using the AMBI were greater than the H’and M-AMBI. However, the AMBI could not indicate the differences of ecological quality levels between sites, but the M-AMBI could effectively distinguish degraded conditions from undegraded, and could sensitively response to the disturbance and pollution of the benthic habitat health.Through the principal component analysis (PCA) and the correlation analyses, the water depth, salinity (S), dissolved inorganic nitrogen (DIN) and sediment texture were selected to been main environmental factors, which influence and restrict benthic community health and habitat health status. According to the main restrictive factors, the assessment of benthic habitat suitability was made in the Huanghe estuary and its adjacent areas, the results indicated that the areas with shallow water, low salinity, relatively heavy pollution and strong hydrodynamism were not suitable for macrobenthos.