北部湾北部浮游植物群落结构及其与营养盐的关系

The relationship between nutrients and phytoplankton community structure in northern Beibu Gulf

根据2011年4月和8月北部湾北部(北部湾20°N以北的海域)的调查数据,北部湾北部春夏两季共鉴定出浮游植物312种,隶属于4门78属,硅藻是主要优势类群。春季优势种为细弱海链藻(Thalassiosira subtilis)、丹麦细柱藻(Leptocylindrus danicus)、奇异棍形藻(Bacillaria paradoxa)和尖刺拟菱形藻(Pseudonitzschia pungens);夏季优势种仅为海链藻(Thalassiosira sp.)。浮游植物群落在春季可划分为2个子群落(spr1和spr2),在夏季可划分为3个子群落(sum1、sum2和sum3)。该海域N/P比值一直处于高的水平,绝大部分的水域表现为磷限制,这可能是硅藻大量生长所造成的。春季spr2群落优势种的柔弱角毛藻(Chaetoceros debilis)与除铵盐之外的营养盐具显著相关关系,奇异棍形藻与环境因子无相关关系。夏季sum3群落优势种的奇异棍形藻与磷酸盐具显著相关关系。分析表明,琼州海峡过道水为北部湾北部输送了磷酸盐,而硅酸盐则主要由陆地径流输入。

Phytoplankton community and nutrient concentration in the northern Beibu Gulf in April and August 2011 were investigated. In this research, 312 phytoplankton taxa were identified, which belonged to four phyla and 78 genera, with Bacillariophyta being the main group. The dominant species wereThalassiosira subtilis,Leptocylindrus danicus,Bacillaria paradoxa, andPseudonitzschia pungens in spring, andThalassiosira sp. in summer. Phytoplankton community in northern Beibu Gulf could be divided into two natural groups in spring (spr1 & spr2) and three in summer (sum1, sum2 & sum3). N/P ratio was in a relatively high level in the study area, and most of the waters were phosphorus limitated which resulted from diatom blossom.Chaetoceros debilis was the dominant species of group spr1 and had significant correlation with nutrient in spring, except for ammonium.Bacillaria paradoxa was the dominant species of group sum3 and had significant correlation with phosphate in summer, but, it was uncorrelated with any environmental factors as the dominant species of group spr2 in spring. Phosphate was transported to northern Beibu Gulf through the Qiongzhou Strait corridor water, and silicate was input by land runoff.