Ecological environment response of benthic foraminifera to heavy metals and human engineering: A case study from Jiaozhou Bay, China

The estuary and coastal zone are the key areas for socio-economic development, and they are also the important channels for pollutants transported to the sea. The construction of the Jiaozhou Bay Bridge changed the hydrodynamic condition of the bay, which made the self-purification capacity of the bay weakened and the pollution in the estuary and adjacent coastal zone become more serious. In this study, 55 surface sediment samples were collected from the three seriously polluted estuaries and the adjacent coastal zone of Jiaozhou Bay to comprehensively study how the benthic foraminifera response to heavy metal pollution and human engineering, and to assess the ecological risks of the bay. A total of 80 species,belonging to 42 genera, were identified in this study. The results showed that Cu, Pb, Cr, Hg, Zn, and As had low to median ecological risks in the study area which would definitely affect the ecological system.The construction of the Jiaozhou Bay Bridge has resulted in pollutants accumulated at the river mouth of Loushan River, which has adverse effects on the survival and growth of benthic foraminifera. The lowest population density and diversity as well as the highest FAI(Foraminiferal Abnormality Index) and FMI(Foraminiferal Monitoring Index) occurred at Loushan River Estuary which indicated that the ecological environment of the northeastern part of Jiaozhou Bay(Loushan River Estuary) had been seriously damaged. Licun River and Haipo River estuaries and the adjacent coastal zone were slightly polluted and had low ecological risk. As a consequence, it suggested that the supervision of industrial and domestic waste discharge and the protection of the ecological environment in northeast Jiaozhou Bay should be paid more attention.