Firm’s Geographical Agglomeration and Location Choice
The skeletal growth rate of Porites coral is an important indicator to reconstruct sea surface temperature (SST). This paper makes use of Porites lutea collected from Yongxing Island, Xisha Islands to construct a coral growth rate thermometer. Based on the thermometer, it reconstructed the SST time series of Xisha sea area since industrial revolution (1880-2007). The result shows that the mean SST was 27.27℃, ranging from 26.1 to 28.5℃ during the period from 1880 to 2007. From 1880 to 1892, SST declined with fluctuations to form a rapid cooling period and SST reached the lowest value of 26.1℃ in 1892. From 1893 to 1935, SST fluctuated all the time to form a platform of low SST. From 1936 to 1957, SST went up at first and then went down, which form a peak of wave. During the period from 1957 to 2003, SST increased rapidly in Xisha Waters. From 2003 to 2007, SST showed a decline trend in Xisha Waters. On the interdecadal time scale, quasi 60-years cycle of climate system might regulate SST change pattern in Xisha waters. At the interannual scale, the intensity of winter monsoon, volcanic activity and ENSO exerted influences on SST in Xisha waters together. In different period, the contribution of different drive factors was different, which lead to the complexity of SST change in Xisha Waters. After 1957 the global warming caused by human activities has become a major driving force of SST increase process in Xisha waters. The SST-fall period from 1880 to 1892 was driven by ENSO, volcanic activity and quasi 60-years cycle of climate system together. The lower winter monsoon velocity causing SST rise counteracted the SST decrease effect of volcanic activity and quasi 60-years cycle of climate system to form a platform of low SST from 1893 to 1935 finally. From 1936 to 1957, SST formed a peak of wave in Xisha Waters, which was driven by the natural variability of the climate system and lower winter monsoon velocity. During the period, the volcanic force resulted in the asymmetry of SST wave crest. During the period from 1957 to 2003, the human-induced greenhouse effects might become the main force to drive the SST increase rapidly in Xisha waters. The cooling process in Xisha waters from 2003 to 2007 might respond to the global warming trend slowdown, which was a result of the interactions between natural forcing and anthropogenic forcing. Anthropogenic forcing always drives SST increases in Xisha waters. Meanwhile, the natural variability of the climate system is in the turn period, the sunspot activity is relatively low, water vapor decreases in the stratosphere, the concentration of atmospheric aerosols increases in the troposphere and the Atlantic meridional overturning circulation accelerates, which drive the temperature reduction. It is obviously that the state is delicate. Once any factor of natural forcing weakens, the declined trend of SST in Xisha waters may be replaced by increase trend of SST again.
The coral reef ecosystem is an ecosystem with high biodiversity and high resource productivity. The ecosystems have important ecological effects, biogeographic functions and socioeconomic benefits. However, coral reef ecosystems are extremely fragile, and global climate change and increasing human activity have led to serious damage and degradation of coral reef ecosystems worldwide. The increase in nutrient concentration caused by anthropogenic activities is also considered as an important reason for the degradation of coral reef ecosystems in some areas. Therefore, it is extremely important to research the relationship between nutrient concentration and coral reef ecosystem decline and investigate nutrient distribution in coral reef area. In order to investigate the effects of surface seawater nutrient distribution on coral reef ecosystem in the coral reef sea area of Luhuitou, Sanya, this study arranged sampling section in the coral reef area and collected surface water samples, then investigated the concentration level of nitrite (NO2-N), nitrate (NO3-N), ammonium (NH4-N), soluble reactive phosphorus (SRP), silicate (SiO3), chlorophyll a (chl a), dissolved Oxygen (DO), etc. in the summers from 2014-2016. The results showed that the average concentrations of Dissolved inorganic nitrogen (DIN) of the three years were 2.941, 1.766, 23.428 μmol/L, those of SRP were 0.493, 0.419, 0.143 μmol/L, those of CHL were 2.304, 1.90, 1.251 mg/m3, and those of SiO3 were 10.275 (2015), 8.506 μmol/L (2016), respectively. The survey was made from 2014 to 2016, the overall concentration of nutrients in summer was higher. The general trend is that the summer nutrients in this area are higher than those in the past 20 years, it may be related to an increase in human activity. In all indicators, the increase trend of DIN is the most significant. N/P showed an upward trend and it means that nitrogen pollution is increasing. Possible causes are mainly from the pollutants emitted during the production process of terrestrial industry and agriculture. The higher nutrient input and the increase of N/P may cause the phosphorus limit of the nutrient, leading to the change of the community structure of the coral reef ecosystem. The change of the community structure will have a negative impact on the stability of the coral reef ecosystem. At the same time, as compared with other coral reefs in the world, the level of nutrient concentration in the reef area of Luhuitou in Sanya is similar to that in Daya Bay of Shenzhen, which is the same as that in Chinese coastal coral reefs. The level of nutrient concentration in the reef area of Luhuitou in Sanya is far higher than that in Zhubi reef area of the Nansha Islands in the South China Sea, and higher than that in other coral reef areas of the world, that means that the shore reef sea area is influenced by a serious land-based nutrients input. Higher levels of nutrients may cause local eutrophication, followed by red tides, have a greater threat to the normal development of coral reefs, and will cause serious degradation of the coral reef ecosystem. Therefore, the increase of nutrient, especially nitrogen, is probably one of the factors that would lead to the degradation of coral reef ecosystem in recent years in the reef area of Luhuitou.
Professor Liu Nanwei pays much attention to the study of Genglubu and the place names of the South China Sea Islands. He has made important contributions to the excavation, textual research and cultural inheritance of the Genglubu and the place names of the South China Sea Islands. This paper briefly reviews the main experiences of Professor Liu Nanwei’s research on the South China Sea Islands in the past 50 years. Professor Liu Nanwei's important contributions to the study on the place names of the South China Sea Islands include: 1) digging out the hand written copies of 10 editions of Genglubu; 2) introducing at the earliest and studying the Survey Report of Fishery and Aquatic resources in Adjacent Waters of the Xisha, Nansha＆ Zhongsha Islands; 3) making textual research on the origin, quantity and nomenclature of the folk place names of the South China Sea Islands.
