Assessing the benthic habitat quality in the Huanghe(Yellow River) Estuary and its adjacent areas using AMBI and M-AMBI

The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe （Yellow River） Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality （BHQ） of the Huanghe Estuary and its adjacent areas is conducted, using AZTI＇s Marine Biotic Index （AMBI） and multivariate AMBI （M-AMBI） based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were ＂high＂ or ＂good＂, because the ecological group I （EGI） and the ecological group II （EGII） were dominant macrobenthic ecological groups in the research area. Owing to a low species＇ richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced （undisturbed or slightly disturbed） sta- tions. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are ＂high＂, and 61% of the stations are slightly disturbed and those of the BHQ are ＂good＂, and the rest are meanly disturbed and those of the BHQ are ＂moderate＂.

Assessing benthic ecological status in coastal area near Changjiang River estuary using AMBI and M-AMBI

The Changjiang(Yangtze)River estuary has been subject to a variety of anthropogenic pressures in recent decades.To assess the ecological health of the coastal benthic ecosystem adjacent to the estuary,three surveys were conducted in 2005,2009,and 2010.The AZTI's Marine Biotic Index(AMBI)and multivariate-AMBI(M-AMBI)were used to analyse the benthic ecological status of this coast.The AMBI indicate that the ecological status of the coast adjacent to the Changjiang River estuary was only slightly degraded in all 3 years.In contrast,the M-AMBI indicated that the ecological status was seriously degraded,a result that is most likely due to pollution and eutrophication induced by human activities.The assessment of the coast's ecological status by the AMBI was not in agreement with that of the M-AMBI at some stations because of lower biodiversity values at those sites.The analysis of the two indices integrated with abiotic parameters showed that the M-AMBI could be used as a suitable bio-indicator index to assess the benthic ecological status of the coast adjacent to the Changjiang River estuary.The reference conditions proposed for the coast of the Changjiang River estuary should be further evaluated in future studies.Designation of local species could also provide an important reference for Chinese waters.To improve the reliability of AMBI and M-AMBI,further research into the ecology of local species is required to understand their arrangement in ecological groups.

Quantifying relations between altered hydrology and fish community responses for streams in Minnesota

Background:Altered hydrology is a stressor on aquatic life,but quantitative relations between specific aspects of streamflow alteration and biological responses have not been developed on a statewide scale in Minnesota.Best sub-sets regression analysis was used to develop linear regression models that quantify relations among five categories of hydrologic metrics(i.e.,duration,frequency,magnitude,rate-of-change,and timing)computed from streamgage records and six categories of biological metrics(i.e.,composition,habitat,life history,reproductive,tolerance,trophic)computed from fish-community samples,as well as fish-based indices of biotic integrity(FIBI)scores and FIBI scores normalized to an impairment threshold of the corresponding stream class(FIBI_BCG4).Relations between hydrology and fish community responses were examined using three hydrologic datasets that represented periods of record,long-term changes,and short-term changes to flow regimes in streams of Minnesota.Results:Regression models demonstrated significant relations between hydrologic explanatory metrics and fish-based biological response metrics,and the five regression models with the strongest linear relations explained over 70%of the variability in the biological metric using three hydrologic metrics as explanatory variables.Tolerance-based biological metrics demonstrated the strongest linear relations to hydrologic metrics.The most commonly used hydrologic metrics were related to bankfull flows and aspects of flow variability.Conclusions:Final regression models represent paired streamgage records and biological samples throughout the State of Minnesota and encompass differences in stream orders,hydrologic landscape units,and watershed sizes.Presented methods can support evaluations of stream fish communities and facilitate targeted efforts to improve the health of fish communities.Methods also can be applied to locations outside of Minnesota with continuous streamgage data and fish-community samples.