Geoscience Reference
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coastal water of the East China Sea fl ows southwestward through Taiwan Strait into
the nSCS (Fang et al., 1998; Xue et al., 2004). On the contrary, during the summer
southwest monsoon, the Guangdong Coastal Current fl ows eastward along the south-
ern coast of mainland China, which eventually fl ows into the East China Sea through
Taiwan Strait. The southwesterly winds also induce Ekman transport toward offshore
and coastal upwelling. The deep water upwells and mixes with the upper water to form
the SCS intermediate water, which fl ows out of the nSCS into the northwestern Pacifi c
Ocean through Luzon Strait (Gong et al., 1992).
In the nSCS, the thermocline occurs all the year round, and the interannual change
in its strength is pronounced (Shi et al., 2001; Yuan and Deng, 1997a, b). Previous
studies have examined on variations in seawater temperature and salinity distributions
(Yang and Liu, 1998; Yuan and Deng, 1998), DO distribution (Lin and Han, 1998),
pollution status along the coast of the nSCS (Li and Chen, 1998) and the fi sheries en-
vironment in the nSCS (Jia et al., 2005). Furthermore, it has been found that due to the
combined effects of monsoons, topography, shape of the coastal line and the inertial
effects, mesoscale eddies (Chen et al., 2005; Li et al., 2003; Xu et al., 2001; Zeng et al.,
1989). Recent studies revealed that the effects of coupling between physical-chemi-
cal-biological oceanographic processes on phytoplankton biomass and production are
important for understanding the infl uence on the long-term environmental changes
and the ecosystem dynamics of the SCS (Liu et al., 2002, 2007; Ning et al., 2004).
However, the long-term changes in environmental conditions and the responses
of the ecosystem in this region have not been well documented yet. The objective of
this study was to analyze the 29 year time series of multidisciplinary observational
data obtained during 1976-2004, aiming at understanding how the environment has
changed and how the ecosystem and biological resources have responded to the envi-
ronmental changes in the nSCS.
It must be pointed out that the data set we adopted in present analysis is large and
from various sources (using data in this study were systemic maintained for the physi-
cal-chemical parameters, but for contemporaneous biological data were collected
from various sources, and we have collected data from the same period of investiga-
tion as best as one can. Inevitably, there are some mismatches between the scales of
physical and chemical parameters refl ecting the processes of environmental change
and the spatial and temporal dimensions of biological investigations, due to the less
frequency for the latter). Although the quality of data might vary throughout the long
period of observation, these data were valuable for the long-term changes in envi-
ronmental conditions and the responses of the ecosystem in this region. Using these
data, we can still fi nd some disciplines about the response of the ecosystem to the en-
vironmental change in the SCS. Regional response to global climate change is clearly
a complicated issue, which is far from well understood. This study made an attempt
to tackle this important issue. And in order to improve our understanding, additional
long-term study is mandatory.
MATERIALS AND METHODS
In this study, data were obtained from winter and summer monitoring along transect
N (Figure 1, an observation transect, including six stations, crossing the nSCS, from
