两种孔径网具对大洋微(小)型浮游植物调查结果的影响——以西南印度洋海域第34次大洋春季航次为例

IMPACT OF PLANKTON NETS WITH DIFFERENT MESHSIZES ON OCEAN PHYTOPLANKTON SURVEY:TAKE THE 34TH SPRING CRUISE IN THE SOUTHWEST INDIA OCEAN AS AN EXAMPLE

浮游植物拖网是海洋浮游植物调查的重要工具,不同网具可以导致不同的调查结果。为研究两种孔径网具对大洋浮游植物调查的影响,于2015年4~5月在西南印度洋分别用筛绢孔径为20和77μm的两种浮游生物网在多个站位进行浮游植物采样。对采集的样品进行浮游植物鉴定,分析比较了两者浮游植物的物种数、细胞丰度、物种丰富度、多样性指数、均匀度指数和优势种。结果表明,在相同采样站位,筛绢孔径为20μm网采样品鉴定得到的平均物种数、平均细胞丰度和平均物种丰富度分别是筛绢孔径为77μm网采样品的2.7、17和2倍,呈显著差异。但两种网采样品的平均多样性指数和平均均匀度指数都无显著差异。此外,筛绢孔径为20μm网采样品中有9种优势种,而筛绢孔径为77μm网采样品中有11种优势种,其中共同的优势种有6种。以上结果说明在寡.营养海域使用20μm孔径的网具可以获得更为全面的浮游植物信息。

Phytoplankton trawl net is a effect tool in the survey of marine phytoplankton.Different results could be obtained by using different nets.To investigate the impact of different mesh sizes of plankton trawl nets on ocean phytoplankton survey,phytoplankton samples were collected by trawl nets in two different mesh sizes of 20μm and 77μm in the Southwest Indian Ocean from April to May,2015.The phytoplankton was identified in taxonomy and the species number,cell abundance,species richness,diversity index,evenness index,and dominant species of the samples collected with the nets of two mesh sizes were compared.Results show that the mean number of species,mean cell abundance,and mean species richness of the 20-μm-mesh samples were significantly greater than those of the 77-μm-mesh samples for about 2.7 times,17 times,and 2 times,respectively.However,no significant difference was shown in mean diversity index and evenness index between the two mesh-size samples.In addition,the number of dominant species was 9 and 11 for 20-μm-mesh and 77-μm-mesh samples,respectively,among them 6 were common.Therefore,using 20-μm-mesh trawl net is recommended for phytoplankton survey in oligotrophic waters as more phytoplankton information can be obtained.