南沙群岛渚碧礁理化环境特征

PHYSICAL AND CHEMICAL ENVIRONMENTCHARACTERISTICS OF ZHUBI CORAL REEFIN SOUTHERN SOUTH CHINA SEA

根据中国科学院南沙综合科学考察队于1993年5月、1994年3月和1999年4月在南沙群岛渚碧礁的考察资料，对渚碧礁理化环境特征作初步分析。渚碧礁海区海水的温度（T）、盐度（S）较礁外海水高，由于礁坪的阻挡，波浪影响大为削弱，珊瑚礁区适宜众多生物种群居住。渚碧礁东北礁坪区溶解氧（DO）含量高，生态环境良好，生物极其丰富；但西南海区DO低，生态环境差。渚碧礁N的变化较大。由于渚碧礁■湖水浅和高温，沉积物间隙水中的营养盐易向上覆海水扩散，加速了营养盐在珊瑚礁生态系中的循环。海水T、DO、总二氧化碳（ΣCO2）等理化因子的日变幅在诸碧礁礁坪区较礁外开阔海域大很多，表明只要有充足的阳光，珊瑚礁生态环境就可以提供十分强烈的光合作用，这也可能是珊瑚礁海区高生产力的重要原因之一。

Based on the investigation data of the Nansha Islands，the southern South Chi- na Sea during the 3 cruises in May 1993，March 1994，and April 1999 respectively，thephysical and chemical environment characteristics of the Zhubi coral reef were studied．The results show that the seawater temperature and salinity inside the Zhubi reef arehigher than those outside the reef．As the bar of the reef flat weakens the wave，the ar- ea inside the coral reef is very suitable for living beings to reside．Compared with thesouthwestern of the Zhubi reef，the dissolved oxygen content（DO）is high in the north- eastern reef flat of the Zhubi reef，and there are abundant organisms owing to good eco- logical environment． The content of N in Zhubi reef shows large change．Due to shallowwater and high water temperature in the lagoon of the Zhubi reef，nutrients In the inter- stitial water of sediment are easy to diffuse to overlying water and join the cycle of the e-cosystem．The diurnal variations of T，DO and CO2 in the reef flat are all larger thanthose outside the reef，which means if there is enough light，photosynthesis will be in-tense in the ecological environment of coral reef，which may be one of the important rea-sons for high productivity of coral reef．