广利港夏季硅藻多样性指数与氮、磷营养盐组成的关系

硅藻种类多,粒径分布范围广,其多样性在很大程度上决定着海洋环境的稳定性,而硅藻多样性指数(H′)的变化受温度、盐度和营养盐等多种因素的影响。为探明营养盐结构与硅藻多样性指数的关系,本研究于2016年夏季采集东营广利港海区38个站位的水样,分别使用锌镉还原比色法、奈乙二胺分光光度法、次溴酸盐氧化法和磷钼蓝分光光度法测定硝酸盐、亚硝酸盐、铵盐和活性磷酸盐的浓度,采用显微镜视野法计数和鉴定硅藻种群。结果显示,近岸河口区的N、P营养盐浓度最高,随着离岸距离增加营养盐浓度降低,但并没有呈现离岸越远浓度越低的现象。N/P在不同站位波动较大,且远大于Redfield比值(N/P=16),其中29个站位超过100。随着N/P的增加,H′呈下降趋势,H′与N/P之间呈中等程度的负相关关系,相关系数为R=-0.43(n=45,P0.01)。实验结果表明,广利港海域营养盐结构失衡有可能影响硅藻种群的均匀分布。

Relationship between the Diatom Diversity Index and Nitrogen and Phosphorus Compositions in the Summer of Guangli Port

There are many kinds of diatoms with wide particle size distribution.The diversity of diatoms largely determines the stability of the marine environment.Variations of diatom diversity index (H'') are affected by a variety of factors,including temperature,salinity and nutrient salts.In order to study the relationship between nutrient salt structure and diatom diversity index,water samples from 38 stations in the sea area of Guangli Port of Dongying City in the summer of 2016 were collected.The concentrations of nitrate,nitrite,ammonium and active phosphate were determined by the zinc-cadmium reduction colorimetric method,the ethylene diamine spectrophotometric method,the hypobromite oxidation method,and the phosphomolybdenum blue spectrophotometric method,respectively.The diatom populations were counted and identified by the microscope field method.The results showed that the concentration of N and P nutrient salts was the highest in the estuary area near the shore,and the concentration of nutrient salt decreased with the increase of offshore distance,but there was no phenomenon that the farther offshore,the lower the concentration.The N/P ratio fluctuated greatly from station to station and was much larger than the Redfield ratio (N/P=16),of which 29 stations exceeded 100.With the increase of N/P ratio,H'' showed a downward trend.There was a moderate negative correlation between H'' and N/P ratio,and the correlation coefficient was R=-0.43 (n=45,P<0.01).The experimental results show that the structural imbalance of nutrients in Guangli Port may affect the uniform distribution of diatom populations.