Response of water-exchange capacity to human interventions in Jiaozhou Bay, China

“…Since the 1980s, the intertidal area of Jiaozhou Bay has been decreasing due to the influence of human activities, such as the reclamation of the sea and the development of saltern (Lei et al, 2013). The water exchange capacity of each region has gradually reduced, resulting in serious eutrophication of seawater (Yang et al, 2018;Yuan et al, 2020). At the beginning of the 21st century, with the implementation of a series of protection measures and the abandonment of salt pans and aquaculture ponds (Yang et al, 2018), the water area of Jiaozhou Bay gradually rebounded, while environmental pollution was also reduced (Lei et al, 2013;Gu et al, 2021a;Yang et al, 2021).…”

Section: Evaluation Of Different Biological Indicesmentioning

confidence: 99%

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

Xu³

et al. 2021

Front. Mar. Sci.

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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′.

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“…Residence time is one of the most frequently used timescales to reflect the water-exchange capacity of a bay. Eulerian definition of residence time is applied in this paper, which has been widely used in numerous shallow coastal areas such as the Archachon Bay (Plus et al, 2009), Bay of Biscay (Grifoll et al, 2013), Jervis Bay (Sun et al, 2018), and Jiaozhou Bay (Yuan et al, 2021). A Eulerian passive tracer with a concentration of 1 was released at each grid cell inside the JZB on 1st February (time t 0 ).…”

Section: Residence Time Calculationmentioning

confidence: 99%

“…The coastline changed a lot due to land reclamation over the last 150 years as discussed in section "Coastline and Tidal Prism Change of Jiaozhou Bay, " which leads to some differences in grid resolution, especially near the coastline change area. According to the sensitivity analysis of horizontal diffusion coefficient conducted by Yuan et al (2021), the horizontal diffusion coefficient D h in Equation 4 is set at a constant of 3 m 2 /s, in order to eliminate the effects of grid resolution on the residence time between different scenarios. Thus, the differences in the residence time were affected only by reclamation.…”

Section: Water-exchange Capacity Evolution Due To Reclamationmentioning

confidence: 99%

“…Zhao et al (2015) studied the sedimentary dynamic enviroment in the western JZB in the 1980s, 2000s, and early 2010s according to collected bottom sediments and numerical model results. Yuan et al (2021) caculated the basin, regional, and local residence time from 1935 to 2013 based on the Finite Volume Community Ocean Model, and found that residence time continued to increase from 1986 to 2000 in the northeast and north-bridge regions but decreased slightly from 2000.…”

Section: Introductionmentioning

confidence: 99%

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Response of Water Environment to Land Reclamation in Jiaozhou Bay, China Over the Last 150 Years

Zhou

et al. 2021

Front. Mar. Sci.

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Jiaozhou Bay (JZB), located at Qingdao City, north China, is a semi-enclosed shallow bay that has undergone large-scale land reclamation and is suffering from a deteriorated water environment. Long-term evolution of JZB with respect of coastline, tidal prism, tidal dynamics, water-exchange capacity, and pollutant transport from 1863 to 2020 was investigated in this paper, using remote sensing images, historical charts, and a numerical model. The JZB was predominated by natural evolution from 1863 to 1935, during which the coastline barely changed. Thereafter, human intervention became intense and more and more natural tidal flats were replaced by salt ponds, aquaculture area, and reclamation very quickly. As a result, tidal prism, area of tidal flats, and area of JZB decreased sharply by 0.290 km3, 182 km2, and 223 km2, respectively, from 1935 to 2020, corresponding to annual decreasing rates being of 123 times, 10 times, 12 times, respectively, as that of before 1935. A numerical model showed that the residual current in JZB tended to be weaker due to the change of coastline and bathymetry, which is not favoring the water-exchange and pollutant transport, especially in the northeast of JZB. The basin residence time increased from 15.5 days in 1935 to 17.6 days in 2020, because of weaker residual tidal current and smaller tidal prism. Local residence time increased significantly near the area with large land reclamation, especially in the northeast and west of JZB. Distribution of dissolved inorganic nitrogen (DIN), in each year, which is the dominant pollutant in JZB, indicated higher DIN concentration and weaker transport along with reclamation. The research on JZB evolution over the last 150 years can provide useful suggestions for the decision-makers of the local government to improve the marine ecosystem. The systematic method to investigate long-term water environment evolution of JZB can be used to study other semi-closed bays.

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Response of water-exchange capacity to human interventions in Jiaozhou Bay, China

Cited by 18 publications

References 45 publications

Capturing Secchi disk depth by using Sentinel-2 MSI imagery in Jiaozhou Bay, China from 2017 to 2021

Capturing Secchi disk depth by using Sentinel-2 MSI imagery in Jiaozhou Bay, China from 2017 to 2021

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

Response of Water Environment to Land Reclamation in Jiaozhou Bay, China Over the Last 150 Years

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