Long-Term Temporal and Spatial Distribution of Coliform Bacteria in Jiaozhou Bay Associated With Human Activities and Environmental Governance

Kaixuan Cui,Jia Liu,Chaofeng Wang,Jun Xuan,Chen Liang,Li Zhao,Haijian Du,Yuan Zhao,Xiaoxia Sun,Tian Xiao,Suheng Li,Si Chen,Yi Dong,Yicong Zhao

doi:10.3389/fmars.2021.641137

Abstract

Coliform bacteria (CB) can be used as an indicator of seawater quality. Long-term monitoring of seawater quality based on CB abundance is lacking in Jiaozhou Bay. In this study, CB abundance in surface seawater of 12 different stations in Jiaozhou Bay was investigated by culturing method. The results showed that: (1) the abundance of CB showed a decreasing tendency during the investigation. During 2004–2007, 2008–2013, and 2014–2017, the average CB abundance decreased significantly, forming a “three stages phenomenon”; (2) the average CB abundance in the first half of the year was lower than that in the second half; (3) the CB abundance in Jiaozhou Bay was spatially heterogeneous. The maximum average CB abundance was observed in the estuary area, and followed by the bay mouth area, the outer bay area, and the inner bay area. The highest abundance may be associated with sewage discharge related to human activities; (4) the abundance of CB was most positively correlated with the concentration of ammonium salt and nitrate, while most negatively correlated with salinity; (5) the years 2007 (2008) and 2013 (2014) were time points of the “three stages phenomenon.” These time points coincide with environmental governance actions, indicating that the actions have played a prominent role in improving seawater quality. Long-term survey of CB can not only serve as an indicator of seawater quality, but also provide a basis for the development of environmental governance strategies and pollution control.

Highlights

Coliform bacteria (CB) are a group of bacteria found in many environments, but are primarily associated with human and animal intestines and wastes
The analyses focused on the data of the whole Jiaozhou Bay were performed to determine whether there was a significant difference in CB abundances considering the factors: (1) different stages of the study, 12 sampling stations, and their interactions; (2) different periods in the annual study, 12 sampling stations, and their interactions; and (3) the 14 years of the investigation, different areas of the sampling stations, and their interactions, respectively
In order to analyze the correlations between CB abundance and environmental factors, and to identify the most important factors affecting the variation of CB abundance in Jiaozhou Bay, the Spearman’s rho correlation analysis and principal component analysis (PCA) among the CB, environmental parameters and heterotrophic bacteria (HB) were calculated using the Psych and Factoextra package in R, respectively

Summary

INTRODUCTION

Coliform bacteria (CB) are a group of bacteria found in many environments, but are primarily associated with human and animal intestines and wastes. Over 8 years (from 1987 to 1994), Schiff and Kinney (2001) used total coliforms as an indicator of bacterial contamination of stormwater discharging into Mission Bay (an enclosed water body) in California, United States. Because of the interactions between natural changes and human activities, Jiaozhou Bay is an ideal study area for ecological investigations (Feng et al, 2018). As Jiaozhou Bay is semi-enclosed, it has been significantly affected by human activities, so long-term research in this area could help explain the environmental response mechanisms. In this regard, the biological communities in Jiaozhou Bay have been investigated at various time scales. As CB are environmental indicator bacteria, in this study we investigated whether their abundance is declining over time and whether it is affected by environmental conditions

MATERIALS AND METHODS

RESULTS

DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT