威海海域微型浮游植物多样性指数与营养盐结构的关系

微型浮游植物(粒径2-20μm,这里把范围扩至2-50μm)多样性在很大程度上决定着海洋环境的稳定性。其多样性指数(H')的变化受多种因素影响。利用计算相关性指数的方法研究了H'与多种环境因子之间的关系,结果表明,在5-27℃温度范围内,H'与水中营养盐结构尤其是NO-3-N/NH+4-N比值相关性显著。2006-2007年对威海沿岸6个海湾进行了4次调查,调查中发现,当水温16℃(16-27℃)时,H'与NO-3-N/NH+4-N值呈显著负相关:2006年7月相关性指数R=-0.526(n=14);2007年10月相关性指数R=-0.575(n=19)。当水温12℃(5-12℃)时,H'与NO-3-N/NH+4-N值呈高度正相关:2006年12月相关性指数R=0.665(n=15);2007年4月相关性指数R=0.415(n=25)。这种规律显示出微型浮游植物在不同的温度条件下对海域中氮源的种类要求可能是有选择的。当水温12℃时(冬季、春季),多数浮游植物优先吸收NO-3-N;而当水温16℃时(夏季、秋季),多数浮游植物优先吸收NH+4-N。

Relationship between structure of nutrient and diversity index of nanophytoplankton in Weihai coastal seawater

Diversity index （Shannon-Weaver index） of nanophytoplankton （H＇） is influenced by many factors.Based on four surveys during 2006-2007,this study focused on the relationship between the structure of nutrients and H＇ in six bays along Weihai coast,China.It was found that H＇ was closely related to nitrate/ammonia ratio （NO3^--N/NH4^＋-N） at temperatures of 5-27℃,showing significant correlations.At 16-27℃,significant and negative correlation was found between H＇ and NO3^--N/NH4^＋-N,with correlation coefficient of-0.526 （n =14） and-0.575 （n =19） in July 2006 and October 2007,respectively.However,when the water temperature was in the range of 5-12℃,there was a highly positive correlation between H＇ and NO3^--N/NH4^＋-N with correlation coefficient of 0.665 （n =15） and 0.415 （n =25） in December 2006 and April 2007,respectively.The results indicated that the nitrogen source preferred by nanophytoplankton was probably different at different temperature.Nanophytoplankton preferentially absorbed NO3^--N at temperatures below 12℃ in winter and spring,while they preferentially utilized NH4^＋-N at temperatures above 16℃ in summer and autumn.