海南岛三亚湾浮游植物和细菌生物量时空分布特征及环境制约因素研究

Spatial-temporal variations of phytoplankton and bacterioplankton biomass and their environmental limiting factors in the Sanya Bay,Hainan Island,China

根据2005年1,4,7和10月4个季度代表月份在海南岛三亚湾进行的现场综合调查资料,分析了海区浮游植物和浮游细菌生物量的空间分布及季节变异特征,探讨了它们与温度,DIN,PO43-,DO,BOD5等生态环境因子的关系.结果表明,三亚湾海区2005年平均叶绿素a浓度为：（2.48±2.97）mg/m^3,浮游植物生物量（C）为：（124.2±148.3）mg/m^3,浮游植物生物量秋季最高,其他季节差异不大,除夏季外,浮游植物生物量（C）均表现为：表层大于底层;年平均浮游细菌丰度为（6.90±2.95）×108个/dm^3,细菌生物量（C）为（13.79±5.90）mg/m^3,细菌生物量夏季最高,往下依次为冬季、春季和秋季,且4个季节均为表层大于底层.4个季节表、底层浮游植物和细菌生物量的空间分布特征明显,均表现为从近岸的三亚河口往外海逐渐降低的趋势,三亚河的陆源输送和入海扩散是造成此分布特征的主要原因.无机营养盐中,DIN是调控浮游植物和细菌生物量的主导因子.位于热带的三亚湾,温度不成为影响二者季节差异的主要因子.浮游细菌生物量和浮游植物生物量的比值BB/PB为：0.06～0.15（平均为0.12）,三亚湾浮游植物生物量和浮游细菌生物量间的相关性非常显著（P〈0.01）,初级生产是影响水域浮游细菌分布的重要因素.

On the basis of the four cruises in the Sanya Bay, a typical tropical coral reef bay of China, located in the northern part of South China Sea in the south coast of Hainan Island, in January （winter）, April （spring）, July （summer） and October （autumn） 2005, the spatial-temporal distribution patterns of phytoplankton and bacteria biomass were studied. The relationships between their biomass and environmental factors, such as temperature, DIN, phosphorus, DO and BODs, were also analyzed. The results showed that the mean chlorophyll a was （2.48±2.97）mg/m^3 , and the mean phytoplankton biomass （PB, C） was （124.2±148. 3） mg/m^3 in the Sanya Bay in 2005, with highest value in autumn. The vertical distribution of PB was shown as the surface〉bottom, except in summer. The annual mean bacterioplankton abundance was （6. 90±2.95）×10^8 cells/dm^3, and the mean bacterioplankton biomass （BB ,C） was （13.79±5.90） mg/m^3 , with highest value appeared in summer, and winter, spring, autumn, in turn. The BB at the surface layer was higher than bottom layer in all four seasons. The distribution of PB and BB at the surface and bottom layers in almost demonstrated the same pattern, which showed that the highest biomass appeared in the estuary of the Sanya River, and their abundance gradually declined offshore. The distribution feature mainly resulted from the terrestrial input from the Sanya River and invasion by the offshore oceanic sea water. In the inorganic nutrients, DIN was the leading factor of regulating PB and BB. Temperature almost had no influence on them in the tropical Sanya Bay, with temperature higher than 22 ℃. The correlation was significant between BB and PB （P〈0.01）, the ratio of BB to PB ranged from 0. 06 to 0. 15 （average value was 0. 12）. Primary production was an important factor in controlling the distribution of bacterioplankton.