中文摘要：

管水母是海洋浮游动物中的重要类群，通常可作为海流或水团的指示种，其分布受温度、盐度和食物的影响。本文根据2011年4月在东印度洋海域（5＆#176;S～5＆#176;N，80＆#176;～98．5＆#176;E）26个站的调查资料，分析了管水母种类组成、丰度分布和群落结构特征。共鉴定管水母37种，以热带大洋广布种和赤道种为主，其中扭形爪室水母 Chelophyes contorta 、巴斯水母 Bassia bassensis 、双小水母 Nanomia bijuga 和短深杯水母Abylopsis eschscholtzi 是调查海域的优势种。依据调查站位设置及环境特征，将调查海域分东部断面、赤道断面和西部断面3个区域。各个调查站种数变化范围为2～14种，东部和西部断面的种类较丰富，而赤道断面近岸区种数低，离岸区种数增多。管水母的平均丰度为（1．04＆#177;0．58）个/m3，分布不均匀，东部断面和西部断面的丰度比赤道断面高，特别是赤道断面近岸区丰度在1．0个/m3以下。调查海区的管水母属于比较典型的热带大洋性生态类群。群落结构分析表明，东部和西部断面的群落结构相似度较高，二者与赤道断面的相似度均较低。调查海域管水母种类和丰度的分布受水文和生物环境因子的综合影响。双小水母 Nanomia bijuga 可作为东部断面和赤道断面近岸区沿岸水团的指示种，锥体浅室水母Lensia conoides 和褶玫瑰水母Rosacea plicata 可作为西部断面100 m 以下涌升水团的指示种。

英文摘要：

Siphonophores,the major constituent of the zooplankton community,are a widespread and abundant group of colonial gelatinous cnidarians that play important roles in the trophic web of the pelagic realm.It has been ob-served that some species of siphonophores could be used as indicators to certain types of waters and ocean current in a particular region.The distribution of siphonophores is influenced by hydrological and biological process,such as temperature,salinity and chlorophyll a concentration.This study aimed to examine the species composition,abun-dance distribution and community structure of siphonophore based on the data obtained from the tropical northeast Indian Ocean in April to May,2011.A total of 37 species of siphonophore were identified characterized by the eco-logical groups with tropical widespread and equator species.The dominant species were mainly represented by Che-lophyes contorta ,Bassia bassensis ,Nanomia bijuga and Abylopsis eschscholtzi .The study area could be divided in-to three transects：eastern,equator and western transects based on the sampling stations and environmental condi-tion.The range of species richness was from 2 to 14,with the high diversity at eastern and western transects,and the increasing trend from the nearshore to offshore at equator transect.An average of siphonophore abundance was （1.04＆#177;0.58）ind/m3 ,with an uneven distribution characterized by high values at eastern and western transects and low values at equator transect.The similarity percentage of community structure between the eastern and western transects was high than equator transect.The results suggested that the distribution of siphonophore was considered to be the result of physical and biological factors.Nanomia bijuga could be regarded as an indicator species for coastal waters at eastern transect,and Lensia conoides ＆amp; Rosacea plicata for uplifted cold waters in the western transect.