Assessing benthic habitat quality using biotic indices in the Laizhou Bay, China

Abstract

As an important part of the Bohai economic rim, the Laizhou Bay has been stressed by serious eco-environmental problems in recent years. In this study, the Shannon-Wiener index (H'), AZTI’s marine biotic index (AMBI) and the multivariate AMBI (M-AMBI) were used to assess the ecological quality status (EQS) of the Laizhou Bay according to macrobenthos data collected annually in August 2011-2014. The results showed that the overall benthic habitat quality in the Laizhou Bay was assessed as “Good”. However, 25% of the samples were classified as “Moderate”, “Bad” or “Poor” status under degraded conditions. Ecological group III (EGIII) species which had a certain tolerance to environmental disturbances had a higher proportion in each station, and most of them had appeared the pollution indicator species Capitella capitata. This indicated that the benthic habitat in the Laizhou Bay had been disturbed and polluted to some extent. The comparison of the three indices evaluation result and the RDA analysis showed that the H' and M-AMBI were more suitable when the relative abundance of the single species was high and the macrobenthic community was significantly imbalanced; when the relative abundance of opportunistic species (EGIV and EGV) was high, the AMBI and M-AMBI could reflected the EQS objectively; in an undisturbed and polluted environment, all the three indices could indicate the benthic habitats quality. In summary, the better correlation between the three indices and environmental factors showed that they were well responsive to the tendency of the benthic habitats quality in the Laizhou Bay.