Data_Sheet_1_Assessment of Benthic Ecological Quality Status Using Multi-Biotic Indices Based on Macrofaunal Assemblages in a Semi-Enclosed Bay.docx

Semi-enclosed bays have physical and chemical characteristics influenced by both land and sea systems and the quality of the benthic environment is always of great concern. Macrofauna are considered good indicators for evaluating the benthic ecological quality status owing to their biological characteristics. In this study, six biotic indices, namely the Shannon–Wiener diversity index (H′), Abundance-Biomass Comparison (ABC) curve, AZTI’s Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI), BOPA index, and BENTIX index, were used to evaluate the adaptability of different biological indices in the bioassessment of the benthic environment in a semi-enclosed bay. In the annual environmental assessment of the study area, the average values of the six indices (H′, ABC curve, AMBI, M-AMBI, BOPA, and BENTIX) were 4.494, 0.182, 2.433, 0.791, 0.033, and 3.813, respectively; accordingly, H′, M-AMBI, and BOPA met the high standards whereas the other indices met the good standards, indicating that the whole study bay was slightly disturbed and had good ecological quality. From the perspective of spatial variation, the benthic environment in the middle of the bay was better than that in the north; the environmental problems in the northeast were particularly noteworthy. In terms of temporal patterns, the benthic environment in winter and summer was significantly better than that in spring and autumn, with obvious seasonal differences. The present results indicate that the H′ and ABC curve based on benthic abundance and biomass should be avoided for environmental assessment in mariculture areas. AMBI and M-AMBI should be used with caution when the percentage of unassigned species is high, in which case H′ is the appropriate choice. When there are few unassigned species, M-AMBI is more conducive for accurate evaluation of the benthic environment than AMBI and H′.

半封闭海湾的理化特征同时受陆海系统共同调控，其底栖环境质量始终是学界关注的重点。大型底栖动物因其独特的生物学特性，被广泛视为评估底栖生态质量状况的优良指示生物。本研究选取6种生物评价指数，即香农-威纳多样性指数（Shannon–Wiener diversity index，H′）、丰度-生物量比较（ABC）曲线、AZTI海洋生物指数（AZTI’s Marine Biotic Index，AMBI）、多变量AMBI指数（multivariate-AMBI，M-AMBI）、BOPA指数以及BENTIX指数，用以评估不同生物指数在某半封闭海湾底栖环境生物评价中的适用性。在研究区域的年度环境评估中，6种指数的平均值分别为4.494、0.182、2.433、0.791、0.033与3.813；其中香农-威纳多样性指数、M-AMBI指数以及BOPA指数符合高质量标准，其余指数则达到良好质量标准，表明整个研究海湾受人为扰动程度较轻，整体生态质量优良。从空间变异特征来看，海湾中部的底栖环境优于北部区域，东北部的环境问题尤为突出，值得重点关注。从时间格局分析，冬季与夏季的底栖环境显著优于春季与秋季，存在明显的季节差异。本研究结果显示，基于底栖丰度与生物量的香农-威纳多样性指数和ABC曲线，不适用于海水养殖区的环境评估。当未分类物种占比较高时，需谨慎使用AMBI与M-AMBI指数，此时香农-威纳多样性指数为更合适的选择。而当未分类物种较少时，M-AMBI指数相较于AMBI与香农-威纳多样性指数，更有助于精准评估底栖环境质量。