This tidal currents dominate the Bay with 2.78 m

This paper aims to identify the causes, impacts and management actions of eutrophication at Jiaozhou Bay. In order to understand this complex multidisciplinary issue, this paper will define and map the Eutrophication phenomenon, and later focus on the issue and the social and ecological aspects of it. Although eutrophication occurs naturally usually in closed systems such as lakes and ponds, however the last five decades, public concerns started rising due to the increased intensity and frequency of these events in aquatic systems. Anthropogenic (or Cultural) eutrophication was the new term used for a natural phenomenon, caused though due to pollution from human activities. Eutrophication phenomenon is the Jiaozhou Bay, has received lately great attention from scientists, decision makers and lay public.

 

1.    The City of Qingdao Geography, Economy and Ecology

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2.1 Geography

 

Qingdao is a coastal city in the southern Peninsula of Shandong with the estimated population for 2014 to be 9,046 million citizens with more than 70% of the population can be characterized as urban. Qingdao is the largest city of its province (Shandong Province) and is located on the east Coast of People’s Republic of China, looking out towards Yellow sea. Qingdao has 12,000 km2 of sea and 11,282 km2 of land and is located on Jiaozhou Bay. Jiaozhou Bay which is also called “the mother Bay of Qingdao”, is a shallow semi closed system of the western part of Yellow sea which is divided into two different sections, the inner and the outer bay (Figure 2.1.1) (Wang et al., 2017; Xu et al, 2016; Yuan et al., 2016; Liu et al., 2010).

 

Figure 2.1.1 The Jiaozhou Bay (Yuan et al., 2016)

The deepest point of Jiaozhou Bay is 64 m and it extends from East to West for 27,8 Km and from South to North. In terms of the hydrologic characteristics, flood tidal currents dominate the Bay with 2.78 m to be the mean tidal range. Freshwater inputs on Jiaozhou Bay, derive from at least 13 different seasonal or no rivers, streams or canals turned into the Bay for domestic or industrial waste water discharge. The largest river, which is seasonal, is Dagu River with an annual runoff of 7.235 × 108 m3, contributing with 89,9% of the total discharge into Jiaozhou Bay for the summer (Wang et al., 2017; Yuan et al., 2016).     

2.2 Economy

 

The Bay serves multiple purposes that contribute into the regional and national economy; shipping, transportation, fishing, recreation, tourism and aquaculture are some of them (Wang et al., 2017). The Qingdao Port, is among the world’s top 20 trading ports (Xu et al., 2016). For the period 1949 to 2004 the population increased by 3.2 million (from 4.1 to 7.3 million). For the same period, a 400 times increase of the GDP per capita has occurred. On the Table 2.2.1, are illustrated the changes in primary production at the area for the aforementioned period (Liu et al., 2010). Other characteristics of the region is laminaria culturing which started in the 1950s, whereas marine animal culture has started in the Bay in the 1990s (Wang et al, 2016).     

 

Table 2.2.1 Changes in local economy in terms of primary production (Liu et al., 2010)

Year

1949

2004

Cultivation area (reduced)

657 × 103 ha

423 × 103 ha

Crop production (increased)

723 × 103 tons yr?1 

2.32 × 106 tons yr?1

Chemical fertilizers (increased)

1.9 × 103 tons yr?1 

325 × 103 tons yr?1

 

2.3 Ecology

 

Jiaozhou Bay is characterized by a variety of habitats and ecosystems. It includes salt ponds, estuarines, intertidal flats, shallow sea water, riverine and lacustrine. The total area of wetlands is 348.25 km2, with the largest wetland in the area to be located at the Dagu River estuary covering a total of 67.80 km2. The plethora of habitats provides an excellent environment for a great wildlife diversity. These wetlands, offer a variety of ecosystem services such as water filtration, flood control, erosion control, pollution mitigation and they are very important habitats for migratory birds (Wang et al., 2017; Xu et al., 2016; Yuan et al., 2016). According to Qingdao Forestry Administration, in 2009 during an investigation of this wetland, the species shown on Table 2.3.1 were found in the area including 24 protected – national important species and 3 endangered (rare) plants (Yuan et al., 2016).  

 

Table 2.3.1 Wetland species in the area (Yuan et al., 2016)

Species

Number of species

Vascular plants

74

Amphibians

8

Reptiles

17

Birds

156

Plankton (phyto- and zoo- plankton)

229

Zoobenthos

81

Nekton

109

2.    Eutrophication in City of Qingdao

2.1  What is Eutrophication?

 

Eutrophication, which can either be anthropogenic or natural (Figure 3.1.1), is often defined as the state where excessive growth of aquatic algae and/or aquatic plants occur. The abundance in water body of Nutrients, sunlight, right temperature and carbon dioxide are some of the main factors of eutrophication (Tucker et al., 2014; Schindler, 2006; Bricker et al, 1999). Nitrogen and phosphorus are the main contributors in terms of nutrients deriving from waste water and urban, industrial and agricultural run off (Bricker et al, 1999). In 1960s, was there first time where eutrophication phenomenon has gaining attention from scientists and public authorities. However, the term “Eutrophication” is much older. Scientists started then, correlating human activities such as intensification of agriculture with algal blooms. So far, anthropogenic eutrophication events have occurred from Japan to the USA and Australia to Adriatic. Natural scientists and decision makers have been working towards reporting, understanding and resolving this rather complex natural and social issue (Schindler, 2006; Bricker et al, 1999).