中国水产科学  2022, Vol. 29 Issue (09): 1326-1336  DOI: 10.12264/JFSC2021-0330
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引用本文 

李雷, 马波, 金星, 金洪宇, 吴松, 陈中祥, 程磊, 王念民, 郝其睿. 西藏雅鲁藏布江大峡谷墨脱江段鱼类群落结构及多样性的空间分布特征[J]. 中国水产科学, 2022, 29(9): 1326-1336. DOI: 10.12264/JFSC2021-0330.
LI Lei, MA Bo, JIN Xing, JIN Hongyu, WU Song, CHEN Zhongxiang, CHENG Lei, WANG Nianmin, HAO Qirui. Structural and diversity characteristics of fish communities in the Motuo reach of the Yarlung Zangbo Grand Canyon[J]. Journal of Fishery Sciences of China, 2022, 29(9): 1326-1336. DOI: 10.12264/JFSC2021-0330.

基金项目

农业农村部农业财政专项“西藏重点水域渔业资源与环境调查”.

作者简介

李雷(1985-),男,博士,副研究员,从事渔业资源及鱼类生态学研究. E-mail:lilei12100821@163.com

通信作者

通信作者:马波,研究员,从事渔业资源及分类学研究,E-mail:hsymabo@163.com;
金星,研究员,从事渔业资源研究,E-mail:jinxing-hlj@163.com

文章历史

收稿日期:2021-07-14
修改日期:2021-11-24
西藏雅鲁藏布江大峡谷墨脱江段鱼类群落结构及多样性的空间分布特征
李雷1,马波1,2,金星1,金洪宇1,吴松1,陈中祥1,程磊1,王念民1,郝其睿1,     
1. 中国水产科学研究院黑龙江水产研究所,农业农村部黑龙江流域渔业资源环境科学观测实验站,黑龙江 哈尔滨 150070
2. 中国水产科学研究院营口增殖实验站,辽宁 营口 115004
摘要:本研究首次对西藏雅鲁藏布江大峡谷墨脱江段鱼类群落结构及多样性的空间分布特征进行分析。根据2015年春季(4月),2017年春季(3—4月)和秋季(11月)在雅鲁藏布江大峡谷墨脱江段及其附属湖泊布裙湖进行的渔业资源调查数据,对墨脱江段鱼类群落结构特征及多样性的空间变化进行了分析。结果表明,春、秋季墨脱江段及布裙湖共捕获鱼类18种,隶属于2目4科13属,其中外来鱼类2种,分别为鲤(Cyprinus carpio)和麦穗鱼(Pseudorasbora parva)。通过形态和分子生物学鉴定发现新物种3种,分别属于裂腹鱼属(Schizothorax)、墨头属(Garra)和鰋属(Exostoma),暂时命名为裂腹鱼属待定名种(Schizothorax sp.)、墨头鱼属待定名种(Garra sp.)和鰋属待定名种(Exostoma sp.)。春季墨脱江段干流和支流的鱼类种类组成存在显著差异,干流主要由大中型鱼类组成,支流主要为小型鱼类。优势种组成也存在差异,仅弧唇裂腹鱼(Schizothorax curvilabiatus)为干流和支流的共有优势种。相对资源量最高的鱼类为弧唇裂腹鱼(S. curvilabiatus),在干流中平均每小时电捕获鱼类重量为9844.7 g;平均每组网捕获鱼类重量446.0 g,支流平均每小时电捕获鱼类重量为486.4 g。物种多样性指数(Hʹ)变化范围为0.95~1.77,丰富度指数()变化范围为0.58~1.13,均匀度指数()变化范围为0.37~0.77,其中干流物种的多样性指数、丰富度指数和均匀度指数均低于支流,表明春季墨脱江段干流鱼类物种多样性明显低于支流。
关键词雅鲁藏布江大峡谷    墨脱江段    布裙湖    优势种    鱼类群落结构    多样性    空间分布    
Structural and diversity characteristics of fish communities in the Motuo reach of the Yarlung Zangbo Grand Canyon
LI Lei1,MA Bo,1,2,JIN Xing,1,JIN Hongyu1,WU Song1,CHEN Zhongxiang1,CHENG Lei1,WANG Nianmin1,HAO Qirui1    
1. Heilongjiang Fisheries Research Institute, Chinese Academy of Fishery Sciences; Scientific Observing and Experimental Station of Fishes Resources and Environment in the Heilongjiang River Basin, Ministry of Agriculture and Rural Affairs, Harbin 150070, China
2. Yingkou Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yingkou 115004, China
Abstract:It is vital to study the spatial distribution characteristics and formation mechanism of biodiversity to enable its conservation. However, how spatial changes affect fish community structure is controversial. The Yarlung Zangbo River is the highest river in the world and nurtures the most distinctive plateau ecosystem and fish resources worldwide. The Yarlung Zangbo River Grand Canyon is located in the lower reaches of the Yarlung Zangbo River and is the deepest canyon in the world. Due to the complex topography and inconvenient transportation in the Yarlung Zangbo Grand Canyon, research on fish community structure and diversity is also unknown in the Motuo reach. This investigation presents the first analysis of the spatial variation in structure and diversity of fish communities in the Motuo reach of the Yarlung Zangbo Grand Canyon. Based on fishery resource survey data in the Motuo reach and Buqun Lake in spring (April) of 2015, and spring (March to April) and autumn (November) of 2017. Spatial variation in the structure and diversity of fish communities in the Motuo reach was determined. The results indicated that 18 fish species were caught, which belonged to 2 orders, 4 families, and 13 genera. There were 2 non-native fish species, including Cyprinus carpio and Pseudorasbora parva. The composition of species has changed compared with historical data. On one hand, there were some differences in the results caused by different classification and identification methods. Historically, morphological identification was primarily used, but molecular genetic methods were used in this study. On the other hand, the fishing methods and intensity were different. Electric capture was used for the first time in this survey. We found three new fish species by morphological and molecular genetics. These new species belonged to Schizothorax, Garra, and Exostoma, and were tentatively named Schizothorax sp., Garra sp., and Exostoma sp., respectively. There was significant spatial variation in species composition between the main stream and its tributaries; the main stream was primarily composed of large-and medium-sized fish, whereas the tributaries consisted primarily of small fish. The predominant species in the fish communities were also different between the main stream and its tributaries; however, Schizothorax curvilabiatus was the dominant species in all water bodies. First, the main factors affecting the composition of the river fish community were the spatial changes in the physical and chemical environment. Second, the variability of environmental factors led to the spatial heterogeneity of fish community structure. Third, the spatial differences in fish composition were also related to their living habits and ecological needs. S. curvilabiatus had the highest relative biomass and abundance. The mean relative resource was 9844.7 g/h by electric fishing, 446 g per gill net in the main stream, and 486.4 g/h by electric fishing in tributaries. The range of Shannon-Wiener diversity index H′ varied from 0.95 to 1.77, and the range of the Margalef species richness index was from 0.58 to 1.13, with the Pielou evenness index being from 0.37 to 0.77. There was a difference between the main stream and its tributaries according to each diversity index, and all diversity indexes in the main stream were lower than the corresponding indexes in tributaries. The unsuitability of the abiotic environment and the low availability of ecological niches and habitat may be the reasons for the low diversity in this reach and may also have contributed to the difference in the degree to which natural disasters threaten tributaries and main streams and the abundance of the organisms in the feed. This survey aims to provide background information to reveal the evolution of fish resources in the lower reaches of the Yarlung Zangbo River under human disturbance after hydropower development and provide a scientific basis for the protection of fish species diversity and fishery resource management in the Yarlung Zangbo Grand Canyon National Nature Reserve.
Key wordsthe Yarlung Zangbo Grand Canyon    Motuo reach    the Buqun Lake    dominant species    fish community structure    diversity    spatial distribution    

雅鲁藏布江是西藏自治区第一大河,也是世界上海拔最高的河流,其独特的自然环境和气候特征孕育了最具特色的高原生态系统和独特的鱼类资源[1-3]。雅鲁藏布江大峡谷为世界第一深峡谷,位于林芝派镇至巴昔卡段的雅鲁藏布江下游段,大峡谷的主体部分位于西藏自治区林芝市墨脱县境内,平均海拔约1200 m,年均气温达18.4 ℃,年均降雨量达2350 mm以上,气候湿润、气温较高且降水充沛,属于热带雨林-常绿阔叶林地区[4]。雅鲁藏布江大峡谷墨脱段海拔落差较大、水流湍急,地质构造复杂,极易受到地震、泥石流滑坡等自然灾害的威胁,该地区的生态环境较为脆弱[5]。墨脱江段的鱼类多数分布范围较为狭窄,生存环境特殊,种群一旦遭到破坏很难得到恢复,如平鳍裸吻鱼(Psilorhynchus homaloptera)、墨脱华鲮(Sinilabeo dero)、墨脱裂腹鱼(Schizothorax molesworthi)、平唇鮡(Parachiloglanis hodgart)、墨脱四须鲃(Barbodes hexagonolepis)等[2,5-6]

空间分布格局是物种与局域生境长期进化形成的一种适应性特征,集中反映了环境对物种空间资源利用的影响[7-8]。研究生物多样性的空间分布特征及形成机制对于保护生物多样性至关重要[9-10]。近年来,针对种群、群落、生态系统等不同尺度保护对象的空间分布格局与环境因子之间相互关系的分析,已经成为生物多样性保护的前提与基础[11-12]。然而,空间变化如何影响鱼类的群落结构仍然存在争议[13]。关于雅鲁藏布江大峡谷墨脱江段鱼类的研究主要集中在分类学、种类组成和个体生物学等方面[2,6,14-18]。由于雅鲁藏布江峡谷较深、地形地貌较为复杂、交通极不便利,对于墨脱江段鱼类群落结构及多样性的研究尚存空白。本研究通过2015年春季(4月)、2017年春季(3—4月)和2017年秋季(11月)在雅鲁藏布江大峡谷墨脱江段进行电捕和网捕结合的调查,对雅鲁藏布江大峡谷墨脱江段干流和支流鱼类群落结构及多样性进行了初步研究,以期为揭示雅鲁藏布江下游鱼类资源在人类扰动下的演变状况提供背景资料,为雅鲁藏布大峡谷国家自然保护区鱼类物种多样性的保护及渔业资源管理提供科学依据。

1 材料与方法 1.1 数据来源

通过主动捕捞方式采集渔获物,聘请专业渔民于2015年春季(4月)、2017年春季(3—4月)和秋季(11月)对雅鲁藏布江大峡谷墨脱江段西莫河大桥至背崩乡干流及其多个支流(包括西莫河、西工河和3条无名支流)(29°16ʹN~29°21ʹN; 95°14ʹE~ 95°20ʹE)及其附属湖泊布裙湖开展渔业资源调查(图1)。2015年春季和2017年秋季仅进行了鱼类种类组成调查,鱼类优势种、多样性、相对资源量以2017年春季数据为基础来分析。捕捞方式包括橡皮艇电捕和三层刺网网捕,其中捕捞获得了当地政府的合法捕捞手续,刺网为定制的三层刺网,网眼大小为1.0 cm、2.0 cm、3.0 cm、4.5 cm,网长10.0 m,高1.2 m, 4种网各1张合在一起称为1组,不同的采样区域按组数进行下网。雅鲁藏布江墨脱江段多个支流及布裙湖选择肩背式电捕。所有鱼类参考《西藏鱼类及其资源》和《青藏高原鱼类》现场进行鉴定,无法鉴定的种类带回实验室利用分子遗传学方法进行确定。

图1  雅鲁藏布江大峡谷墨脱江段鱼类资源采样江段分布图 Fig. 1  The sampling area of fish resources investigation in the Motuo reach of the Yarlung Zangbo Grand Canyon
1.2 计算公式 1.2.1 群落多样性指数

用Shannon-Wiener多样性指数()、Margalef种类丰富度指数()和Pielou均匀度指数()来分析雅鲁藏布江大峡谷墨脱江段鱼类物种多样性[19]。由于不同物种种间及种内个体差异较大,Wilhm[20]提出用生物量表示的多样性更接近种类间的能量分布,因此本研究根据鱼类物种生物量计算物种多样性。

Shannon-Wiener多样性指数:

$H' = - \sum\limits_{i = 1}^s {{P_i}} \ln {P_i}$

Margalef物种丰富度指数:

$D' = (S - 1)/\ln W$

Pielou均匀度指数:

$J' = H'/\ln S$

式中,S为鱼类种类数,W为总渔获物重量,Pi为第i种鱼占总渔获物重量的比例。

1.2.2 相对重要性指数

利用Pinkas等[21]提出的相对重要性指数IRI (index of relative important)对鱼类群落优势种结构的组成进行评价。

IRI=(N+WF×104

式中,N为某一种类的尾数占总渔获物尾数的比例(%), W为某一种类的重量占总重量的比例(%), F为某一种类出现的站位数量占总调查站位数量的比例(%)。由于雅鲁藏布江大峡谷地形较为复杂,很多江段人类较难涉及,为利于数据分析,本研究将干流作为一个站位,所有支流作为一个站位。

依据相对重要性指数IRI数值大小来确定物种在群落中的重要性,本研究将IRI>1000的种类定为优势种,100<IRI<1000的种类为重要种[22]

1.2.3 种类组成相似性指数

本研究选择Jaccard相似性指数来表示各年份或区域之间鱼类物种相似性[23]

物种相似性指数:

${J_s} = \frac{c}{{a + b - c}} \times 100\% $

式中,ab分别为相邻两个采样区域的物种数,c为其共有的物种数。

1.2.4 鱼类相对资源量

本研究利用相对生物密度指数和相对生物量指数来表示鱼类相对资源量,其中相对生物密度指数为每小时捕捞的渔获物尾数,单位为尾/h;相对生物量指数为每小时捕捞的渔获物重量,单位为g/h。

2 结果与分析 2.1 种类组成

2015年春季(4月)、2017年春季(3—4月)和秋季(11月)于雅鲁藏布江大峡谷墨脱江段及其附属湖泊布裙湖捕获鱼类18种,隶属于2目4科13属(表1),其中墨脱江段捕获土著鱼类15种,隶属于2目4科11属;外来鱼类2种,隶属于1目1科2属,为鲤(Cyprinus carpio)和麦穗鱼(Pseudorasbora parva);布裙湖仅捕获鱼类1种,为全唇裂腹鱼(Schizothorax integrilabiatus)。墨脱江段土著鱼类仅由鲤形目和鲇形目鱼类组成,其中鲤形目种类最多,3科6属9种,占土著鱼类种类总数的60.0%;其次为鲇形目,1科5属6种,占40.0%。通过形态学和分子生物学鉴定发现新物种3种,分别为裂腹鱼属、墨头属和鰋属,暂时命名为裂腹鱼属待定名种(Schizothorax sp.)、墨头鱼属待定名种(Garra sp.)和鰋属待定名种(Exostoma sp.)[6]

雅鲁藏布江大峡谷墨脱江段干流和支流土著鱼类种类组成不同,两个区域物种相似性指数为25%,其中干流捕获鱼类8种,隶属于2目3科6属,鲤科最多,6种,占干流土著鱼类种类总数的75.0%;鮡科1种,为黄斑褶鮡(Pseudecheneis sulcatus);裸吻鱼科1种,为平鳍裸吻鱼(P. homaloptera)。支流共捕获鱼类12种,隶属于2目4科9属,鮡科鱼类最多,6种,占种类总数的50.0%;其次为鲤科,4种,占种类总数的33.3%;鳅科和裸吻鱼科各1种,分别为浅棕条鳅(Nemacheilus subfuscus)和平鳍裸吻鱼(P. homaloptera)。其中弧唇裂腹鱼(S. curvilabiatus)、墨脱裂腹鱼(S. molesworthi)、墨头鱼待定种(Garra sp)、平鳍裸吻鱼(P. homaloptera)和黄斑褶鮡(P. sulcatus)在干支流中均有出现;墨脱华鲮(S. dero)仅在干流中出现。

本研究把最大个体体长小于20 cm的鱼类称为小型鱼类,墨脱江段鱼类组成以小型鱼类为主,种类数11种,占到土著鱼类种类总数的73.3%(表1);大型鱼类4种,分别为墨脱四须鲃(Barbodes hexagonolepis)、墨脱华鲮(S. dero)、裂腹鱼属待定名种(Schizothorax sp.)和弧唇裂腹鱼(S. curvilabiatus),其中墨脱四须鲃(B. hexagonolepis)最大体长达到59.5 cm,全长71 cm,体重5.5 kg。布裙湖的全唇裂腹鱼(S. integrilabiatus)为大型鱼类。

表1  2017年雅鲁藏布江下游墨脱江段渔获鱼类名录 Tab. 1  List of fish species in the catches in the Motuo Reach of the Yarlung Zangbo Grand Canyon in 2017
2.2 优势种及重要种组成

2017年春季,雅鲁藏布江大峡谷墨脱江段干流和支流优势种类组成存在空间差异。墨脱江段共采集到土著鱼类15种,其中优势种4种,弧唇裂腹鱼(S. curvilabiatus)为绝对优势种,然后依次为黄斑褶鮡(P. sulcatus)、墨脱四须鲃(B. hexagonolepis)和墨头鱼属待定种(Garra sp.),占2017年春季鱼类总数的26.57%;重要种5种,占种类数的33.33%。墨脱江段干流采集到土著鱼类8种,优势种4种和全流域的优势种组成相同;重要种2种,为墨脱华鲮(S. dero)和裂腹鱼属待定名种(Schizothorax sp.)。支流采集到土著鱼类12种,优势种5种,与干流优势种类组成存在较大差异,分别为弧唇裂腹鱼(S. curvilabiatus)、墨脱裂腹鱼(S. molesworthi)、西藏墨头鱼(G. kempi)、平鳍裸吻鱼(P. homaloptera)和藏鰋(E. labiatum),其中仅弧唇裂腹鱼(S. curvilabiatus)与干流优势种类存在重叠;重要种5种与干流的重要种类完全不同,分别为墨头鱼属待定名种(Garra sp.)、黄斑褶鮡(P. sulcatus)、浅棕条鳅(N. subfuscus)、平唇鮡(P. hodgarti)和鰋属待定名种(Exostoma sp.)(表2)。

表2  2017年春季雅鲁藏布江大峡谷墨脱江段鱼类群落重要种类的空间变化 Tab. 2  Spacial variation of important species of fish community in the Motuo reach of the Yarlung Zangbo Grand Canyon in spring of 2017
2.3 物种多样性的空间变化

2017年春季,雅鲁藏布江大峡谷墨脱江段干流和支流的鱼类物种多样性存在空间差异,墨脱江段干流物种的多样性指数、丰富度指数和均匀度指数均低于支流的物种多样性指数。墨脱江段鱼类物种多样性指数()变化范围为0.95~1.77,丰富度指数()变化范围为0.58~1.13,均匀度指数()变化范围为0.37~0.77 (图2)。

2.4 鱼类相对资源量

除了在干流中网捕渔获物的相对生物密度指数最高的鱼类为黄斑褶鮡外,2017年春季雅鲁藏布江大峡谷墨脱江段干流和支流中相对生物密度和相对生物量指数最高的鱼类均为弧唇裂腹鱼。在干流船式电捕中墨脱四须鲃和墨头鱼属待定名种的相对生物密度指数相似,仅次于弧唇裂腹鱼,然而墨脱四须鲃相对生物量指数远大于墨头鱼属待定名种。支流中墨脱裂腹鱼的相对资源量较高(表3)。

图2  2017年春季雅鲁藏布江大峡谷墨脱江段鱼类物种多样性的空间变化 Fig. 2  Spatial variation of biodiversity indices of fish species in the Motuo reach of the Yarlung Zangbo Grand Canyon in spring of 2017
表3  雅鲁藏布江大峡谷墨脱段鱼类的平均相对资源量指数的空间变化 Tab. 3  Spacial variation in mean index of relative abundance (IRI) of fishery species in Motuo reach of the Yarlung Zangbo Grand Canyon
3 讨论 3.1 鱼类群落结构的空间变化

据20世纪90年代的调查数据,雅鲁藏布江大峡谷墨脱江段具有土著鱼类13种,隶属于4科11属,布裙湖鱼类1种,为全唇裂腹鱼[1-2]。本次调查雅鲁藏布江大峡谷墨脱江段捕获土著鱼类15种,隶属于4科11属,与历史调查结果相比数量有所增加,然而墨脱阿波鳅(Aborichthys kempi)和细体纹胸鮡(Glyptothorax gracilis)等2种鱼类在本次调查中未能采集到,布裙湖的种类与历史数据进行对比没有发生变化。导致数量增加且种类组成发生变化的原因,一方面,鮡科鱼类“同物异名”和“同名异物”的现象较为常见[6,24-26],分类鉴定方法的不同导致结果存在一定的差异,本研究采用分子遗传手段,比仅从外观形态学进行分类鉴定更为准确;另一方面,捕捞方式和强度不同,历史上墨脱江段鱼类捕获主要为网捕,本次首次选择了船式电捕对墨脱江段鱼类资源开展调查,调查更为全面,如裂腹鱼属待定名种(Schizothorax sp.)在本次船式电捕的渔获物中被发现;第三,本次调查范围小于历史上的调查,本次调查范围为墨脱西莫河大桥至背崩乡,由于特殊原因背崩乡以下没有采样,据历史调查数据显示墨脱阿波鳅(Aborichthys kempi)分布于背崩乡以南的里戛地区[2]。雅鲁藏布江大峡谷墨脱江段海拔较低、气候湿润,鱼类种类组成与高海拔的雅鲁藏布江中上游存在显著差异,仅黄斑褶鮡重叠,其中雅鲁藏布江中上游鱼类为典型的青藏高原种类,雅鲁藏布江下游除了青藏高原种类外还有中国-印度鱼类区系的物种,也进一步表明雅鲁藏布江下游鱼类具有明显的高海拔向低海拔的过渡区特征[2-3,27-28]。在雅鲁藏布江下游支流首次发现了鲤和麦穗鱼等外来鱼类,由于这些外来鱼类发现频次低,尾数少,初步评估没有对土著鱼类造成影响,然而由于墨脱段为原始水域,外来鱼类入侵成功,会对土著鱼类资源造成严重破坏,建议要加强对外来鱼类的管理。

本研究结果显示雅鲁藏布江大峡谷墨脱江段鱼类群落组成在相同季节存在着显著的空间差异,干流和支流两个区域物种相似性指数较低,为25%。首先,影响河流鱼类群落组成的主要因素为物理化学环境的空间变化[29-30]。如避难场所的可用性[31]、底质[32]、水深[33]、流速[34]、水温[35]等因素都已被证明会影响河流的鱼类群落组成。现场调查表明,墨脱干流生境和支流生境存在显著不同,干流透明度较低,水较深,底质多为较大的卵石;支流透明较高,水较浅,底质多为较小的卵石。其次,环境因素的多变性导致了鱼类群落结构在空间上表现出较大的空间异质性[36]。墨脱段极易受到地震、泥石流滑坡等自然灾害的威胁,环境因素多变[5]也可能导致了墨脱干流和支流的鱼类群落结构存在空间差异。第三,鱼类组成空间的差异也与其自身的生活习性相关[37]。Yan等[38]对中国青衣江局部生境和河流空间对鱼类聚集影响的研究结果显示,鱼类的群落组成受生境环境和河流空间位置影响较大。如鮡科鱼类多为底层小型鱼类,喜栖息于山涧溪流的急流水中[39]

相关研究表明水深对鱼类的空间分布具有重要的影响[40],水体具有一定的深度,更适合大型鱼类生活[41],该结果在本研究中也得到体现,水体较深的雅鲁藏布江下游干流鱼类组成以大中型鱼类为主。雅鲁藏布江大峡谷墨脱江段干流鱼类种类组成主要为大中型鱼类,如弧唇裂腹鱼、墨脱四须鲃、墨脱华鲮、裂腹鱼属待定名种和墨脱裂腹鱼等5种鲤科鱼类,占干流捕捞渔获物种类总数的62.5%,支流中除了弧唇裂腹鱼、墨脱裂腹鱼和墨头鱼属待定名种为大中型鱼类外,其余种类均为小型鱼类,占支流发现渔获物种类总数的72.7%。其中黄斑褶鮡和平鳍裸吻鱼在干流中主要为产卵的成鱼,这可能与黄斑褶鮡和平鳍裸吻鱼具有洄游习性有关,这有待于进一步研究。

3.2 物种多样性的空间分布特征

通过对雅鲁藏布江大峡谷墨脱江段干流春季鱼类物种多样性分析结果,墨脱江段干流物种多样性指数(H′)、丰富度指数(D′)和均匀度指数(J′)均比支流低,表明墨脱江段干流春季鱼类物种多样性明显低于支流。墨脱江段干流鱼类物种多样性低的主要原因可能有:(1)干流生存环境恶劣,可利用的生态位和生境较小。鱼类物种多样性的差异与其生存环境特征具有紧密的关系[42],生存环境越适合,可利用的生态位和生境越大,物种多样性越高[36,43-44]。雅鲁藏布江大峡谷墨脱江段水流湍急,地质构造复杂,地震、泥石流滑坡等自然灾害发生较为频繁[5],导致墨脱江段干流鱼类栖息地受自然灾害干扰程度大于支流,干流鱼类物种多样性较低。如,鮡科鱼类与水环境具有较紧密的关系,对水文特征的变化极为敏感[39]。本研究调查结果显示,扁头鮡平唇鮡、藏鰋等鮡科鱼类仅栖息于支流。(2)干流饵料生物丰度低于支流。生物多样性与饵料生物的丰富程度呈正相关[45],饵料生物丰度较低,导致鱼类繁衍和生长受到限制[46]。墨脱江段干流水流速度较大、透明度较低、水较深,致使饵料生物不充足;另外,现场调查结果显示墨脱支流的饵料生物平均丰度高于干流,使得干流鱼类物种多样性低于支流。(3)干流种类数量及分布均匀度较低。物种多样性与种的数量及分布的均匀度密切相关,物种越丰富,分布越均匀,物种多样性越高[47-48]。在雅鲁藏布江干流中发现鱼类的数量低于支流中鱼类的数量,其中干流中发现8种,支流中发现12种,且支流物种的均匀度指数高于干流。相关研究表明,物种多样性能够反应群落结构稳定性[49],也表明干流的鱼类群落稳定性相对较低。

参考文献
[1]
Wu Y F, Wu C Z. The Fishes of the Qinghai Xizang Plateau[M]. Chengdou: Sichuan Publishing House of Science Technology, China, 1992: 133-562. [武云飞,吴翠珍. 青藏高原鱼类[M]. 成都:四川科学技术出版社,1992: 133-562.].》Google Scholar
[2]
Bureau of Aquatic Products of Tibet Autonomous Region. Fishes and Fish Resources in Tibet, China[M]. Beijing: China Agriculture Press, 1995: 1-143. [西藏自治区水产局. 西藏鱼类及其资源[M]. 北京:中国农业出版社,1995: 1-143.].》Google Scholar
[3]
Ji F, Ma B, Wang B Q. The Fisheries resources and environment research report of the middle reaches of the Yarlung Zangbo River[M]. Beijing: China Agriculture Press, 2019: 1-68. [纪锋,马波,王炳谦. 雅鲁藏布江中游渔业资源与环境科考报告[M]. 北京:中国农业出版社,2019: 1-68.].》Google Scholar
[4]
Yang N, Zhou X W. Medog plant[M]. Beijing: China Forestry Publishing House, 2015. [杨宁,周学武. 墨脱植物[M]. 北京:中国林业出版社,2015.].》Google Scholar
[5]
Huang F S, Song Z S, Jiang S Q, et al. Biodiversity and environment frangibility in southeast Tibet, China[J]. Southwest China Journal of Agricultural Sciences, 2006, 19(1): 35-39. [黄复生,宋志顺,姜胜巧,等. 西藏东南部生物多样性和生态环境脆弱性分析[J]. 西南农业学报,2006, 19(1): 35-39.].》Google Scholar
[6]
Jin X, Ma B. Fishes and resources in the lower reaches of the Yarlung Zangbo River of the Xizang Plateau[M]. Beijing: China Agriculture Press, 2020. [金星,马波. 西藏雅鲁藏布江下游鱼类及资源[M]. 北京:中国农业出版社,2020.].》Google Scholar
[7]
Wang Z S, Chen M H, Lv C, et al. Species diversity and spatio-temporal distribution patterns of icefishes (Salangidae) in Poyang Lake[J]. Acta Ecologica Sinica, 2006, 26(5): 1337-1344. [王忠锁,陈明华,吕偲,等. 鄱阳湖银鱼多样性及其时空格局[J]. 生态学报,2006, 26(5): 1337-1344.].》Google Scholar
[8]
Liu X X, Wang J, Zhang Y L, et al. Comparison between two GAMs in quantifying the spatial distribution of Hexagrammos otakii in Haizhou Bay, China[J]. Fisheries Research, 2019, 218: 209-217..》Google Scholar
[9]
Abrams P A. Monotonic or unimodal diversity-productivity gradients: What does competition theory predict?[J]. Ecology, 1995, 76(7): 2019-2027..》Google Scholar
[10]
Chapin III F S, Zavaleta E S, Eviner V T, et al. Consequences of changing biodiversity[J]. Nature, 2000, 405(6783): 234-242..》Google Scholar
[11]
Zhang L L, Jiang R J, Xu Y P, et al. Related affecting factors in community structure characteristics of the crustacean assemblages in Yueqing Bay[J]. Journal of Fisheries of China, 2020, 44(3): 447-460. [张琳琳,蒋日进,徐义平,等. 乐清湾甲壳类群落结构特征及其影响因素[J]. 水产学报,2020, 44(3): 447-460.].》Google Scholar
[12]
Shuai F M, Li X H, Liu Q F, et al. Spatial patterns of fish diversity and distribution in the Pearl River[J]. Acta Ecologica Sinica, 2017, 37(9): 3182-3192. [帅方敏,李新辉,刘乾甫,等. 珠江水系鱼类群落多样性空间分布格局[J]. 生态学报,2017, 37(9): 3182-3192.].》Google Scholar
[13]
Smith T A, Kraft C E. Stream fish assemblages in relation to landscape position and local habitat variables[J]. Transactions of the American Fisheries Society, 2005, 134(2): 430-440..》Google Scholar
[14]
Li L, Ma B, Wang J L, et al. Length-weight relationships of four fish species from the MoTuo reach of the Yarlung Zangbo River, southwest China[J]. Journal of Applied Ichthyology, 2016, 32(6): 1313-1314..》Google Scholar
[15]
Gong J H, Wang J L, Li L, et al. Preliminary study on age and growth of Schizothorax integrilabiatus in the Buqun Lake, Tibet[J]. Freshwater Fisheries, 2017, 47(6): 26-31. [龚君华,王继隆,李雷,等. 西藏布裙湖全唇裂腹鱼年龄与生长的初步研究[J]. 淡水渔业,2017, 47(6): 26-31.].》Google Scholar
[16]
Ma Q Z, Ma B, Li L, et al. Analysis of genetic diversity of Pseudecheneis sulcata populations from the Yarlung Zangbo River in Tibet based on mitochondrial DNA cytochrome b gene and control region sequence[J]. Chinese Journal of Zoology, 2019, 54(5): 701-710. [马清芝,马波,李雷,等. 基于线粒体DNA细胞色素b基因和控制区序列分析西藏雅鲁藏布江黄斑褶鮡种群遗传多样性[J]. 动物学杂志,2019, 54(5): 701-710.].》Google Scholar
[17]
Jin H Y, Li L, Jin X, et al. Fecundity of Pseudecheneis sulcatus in downstream of Yarlung Zangbo River in Xizang[J]. Fisheries Science, 2020, 39(5): 744-751. [金洪宇,李雷,金星,等. 西藏雅鲁藏布江下游黄斑褶鮡的个体繁殖力研究[J]. 水产科学,2020, 39(5): 744-751.].》Google Scholar
[18]
Jin H Y, Li L, Jin X, et al. Age and growth of Pseudecheneis sulcatus in lower reach of Yarlung Zangbo River of Medog County reach[J]. Freshwater Fisheries, 2020, 50(2): 10-17. [金洪宇,李雷,金星,等. 雅鲁藏布江下游墨脱江段黄斑褶鮡的年龄结构与生长特征[J]. 淡水渔业,2020, 50(2): 10-17.].》Google Scholar
[19]
Qiao Y L, Chen Z Z, Lin Z J. Changes of community structure of fishery species during spring and autumn in Beibu Gulf[J]. Journal of Fishery Sciences of China, 2008, 15(5): 816-821. [乔延龙,陈作志,林昭进. 北部湾春、秋季渔业生物群落结构的变化[J]. 中国水产科学,2008, 15(5): 816-821.].》Google Scholar
[20]
Wilhm J L. Use of biomass units in Shannon’s formula[J]. Ecology, 1968, 49(1): 153-156..》Google Scholar
[21]
Pinkas L, Oliphant M S, Iverson I L K. Food habits of albacore, bluefin tuna, and bonito in California waters[J]. Calif Dep Fish Game Fish Bull, 1971, 152: 1-105..》Google Scholar
[22]
Liu Y S, Tang S K, Li D M, et al. Characteristics of the fish community structure in Jiangsu reach of the Huaihe River[J]. Journal of Fishery Sciences of China, 2020, 27(2): 224-235. [刘燕山,唐晟凯,李大命,等. 淮河江苏段鱼类群落结构特征[J]. 中国水产科学,2020, 27(2): 224-235.].》Google Scholar
[23]
Jaccard P. The distribution of the flora in the alpine zone.1[J]. New Phytologist, 1912, 11(2): 37-50..》Google Scholar
[24]
Zhou W, Li X, Yang Y. Progress of studies on the phylogeny and geographic distribution pattern of catfish glyptosternoid (Sisoridae) in China[J]. Zoological Research, 2005, 26(6): 673-679. [周伟,李旭,杨颖. 中国鮡科鰋鮡群系统发育与地理分布格局研究进展[J]. 动物学研究,2005, 26(6): 673-679.].》Google Scholar
[25]
Kong D P. Studies on the phylogeny and zoogeography of glyptosternoid fishes[D]. Beijing: Institute of Zoology, Chinese Academy of Sciences, 2006: 1-116. [孔德平. 鰋鮡鱼类(Glyptosternoid fishes)的系统进化和动物地理学研究[D]. 北京:中国科学院昆明动物研究所,2006: 1-116.].》Google Scholar
[26]
Jiang W S. Studies on the classification, phylogeny and biogeography of Sparidae and Sparidae[D]. Beijing: University of Chinese Academy of Sciences, 2012: 1-184. [蒋万胜. 鮡科及纹胸鮡属鱼类分类、系统进化与生物地理学研究[D]. 北京:中国科学院大学,2012: 1-184.].》Google Scholar
[27]
Yang H Y, Huang D M. A preliminary investigation on fish fauna and resources of the upper and middle Yalu Tsangpo River[J]. Journal of Huazhong Normal University (Natural Sciences), 2011, 45(4): 629-633. [杨汉运,黄道明. 雅鲁藏布江中上游鱼类区系和资源状况初步调查[J]. 华中师范大学学报(自然科学版), 2011, 45(4): 629-633.].》Google Scholar
[28]
Li L, Ma B, Jin X, et al. Quantitative assessment of the priority conservation of Schizothoracinae fishes in the middle Yarlung Zangbo River, Tibet[J]. Journal of Fishery Sciences of China, 2019, 26(5): 914-924. [李雷,马波,金星,等. 西藏雅鲁藏布江中游裂腹鱼类优先保护等级定量评价[J]. 中国水产科学,2019, 26(5): 914-924.].》Google Scholar
[29]
Grossman G D, Ratajczak R E Jr, Crawford M, et al. Assemblage organization in stream fishes: Effects of environmental variation and interspecific interactions[J]. Ecological Monographs, 1998, 68(3): 395-420..》Google Scholar
[30]
Dauwalter D C, Splinter D K, Fisher W L, et al. Biogeography, ecoregions, and geomorphology affect fish species composition in streams of eastern Oklahoma, USA[J]. Environmental Biology of Fishes, 2008, 82(3): 237-249..》Google Scholar
[31]
Abes S S, Agostinho A A. Spatial patterns in fish distributions and structure of the ichthyocenosis in the A’gua Nanci stream, upper Parana’River basin, Brazil[J]. Hydrobiologia, 2001, 445: 217-227..》Google Scholar
[32]
Aadland L P. Stream habitat types: Their fish assemblages and relationship to flow[J]. North American Journal of Fisheries Management, 1993, 13(4): 790-806..》Google Scholar
[33]
Harvey B C, Stewart A J. Fish size and habitat depth relationships in headwater streams[J]. Oecologia, 1991, 87(3): 336-342..》Google Scholar
[34]
Magoulick D D. Effects of predation risk on habitat selection by water column fish, benthic fish and crayfish in stream pools[J]. Hydrobiologia, 2004, 527(1): 209-221..》Google Scholar
[35]
Wang L Z, Lyons J, Rasmussen P, et al. Watershed, reach, and riparian influences on stream fish assemblages in the Northern Lakes and Forest Ecoregion, USA[J]. Canadian Journal of Fisheries and Aquatic Sciences, 2003, 60(5): 491-505..》Google Scholar
[36]
Selleslagh J, Amara R. Environmental factors structuring fish composition and assemblages in a small macrotidal estuary (eastern English Channel)[J]. Estuarine, Coastal and Shelf Science, 2008, 79(3): 507-517..》Google Scholar
[37]
Yin M C. Fish Ecology[M]. Beijing: China Agriculture Press, 1995. [殷名称. 鱼类生态学[M]. 北京:中国农业出版社,1995.].》Google Scholar
[38]
Yan Y Z, Xiang X Y, Chu L, et al. Influences of local habitat and stream spatial position on fish assemblages in a dammed watershed, the Qingyi Stream, China[J]. Ecology of Freshwater Fish, 2011, 20(2): 199-208..》Google Scholar
[39]
Zhou W, Li M H. The study on relationship between biodiversity and habitat of catfish family Sisoridae (Siluriformes) in China[J]. Journal of Yunnan Agricultural University, 2006, 21(6): 811-815, 830. [周伟,李明会. 鮡科鱼类多样性与栖境的关系[J]. 云南农业大学学报,2006, 21(6): 811-815, 830.].》Google Scholar
[40]
Li S F, Cheng J H, Yan L P. Spatial structures of fish communities on the continental shelf of the East China Sea[J]. Acta Ecologica Sinica, 2007, 27(11): 4377-4386. [李圣法,程家骅,严利平. 东海大陆架鱼类群落的空间结构[J]. 生态学报,2007, 27(11): 4377-4386.].》Google Scholar
[41]
Englund G, Krupa J J. Habitat use by crayfish in stream pools: Influence of predators, depth and body size[J]. Freshwater Biology, 2000, 43(1): 75-83..》Google Scholar
[42]
Yuan M, Tang Y, Xu S N, et al. Community structure of fishery resources from the Nansha waters of Pearl River Estuary in autumn[J]. South China Fisheries Science, 2017, 13(2): 18-25. [袁梦,汤勇,徐姗楠,等. 珠江口南沙海域秋季渔业资源群落结构特征[J]. 南方水产科学,2017, 13(2): 18-25.].》Google Scholar
[43]
Zhang M Y, Liu K, Duan J R, et al. Study on catch composition and diversity seasonal change of set net in Changshu section of the Yangtze River[J]. Chinese Agricultural Science Bulletin, 2011, 27(26): 92-96. [张敏莹,刘凯,段金荣,等. 长江常熟段定置张网渔获物组成及多样性季节变化分析[J]. 中国农学通报,2011, 27(26): 92-96.].》Google Scholar
[44]
Wang Y Q, Wang J, Xue Y, et al. Width and overlap of spatial and temporal ecological niches for main fish species in the Yellow River Estuary[J]. Journal of Fishery Sciences of China, 2019, 26(5): 938-948. [王雨群,王晶,薛莹,等. 黄河口水域主要鱼种的时空生态位宽度和重叠[J]. 中国水产科学,2019, 26(5): 938-948.].》Google Scholar
[45]
Yan W C, Song W H, Yu C G, et al. Studies on fish diversity and community structure in spring and autumn in Oujiang Estuary[J]. Transactions of Oceanology and Limnology, 2018(6): 132-141. [颜文超,宋伟华,俞存根,等. 瓯江口海域春秋季鱼类多样性及群落结构研究[J]. 海洋湖沼通报,2018(6): 132-141.].》Google Scholar
[46]
Liu R Y. Ecology and Living Resources of Jiaozhou Bay[M]. Beijing: Science Press, 1992. [刘瑞玉. 胶州湾生态学和生物资源[M]. 北京:科学出版社,1992.].》Google Scholar
[47]
Pielou E C. The measurement of diversity in different types of biological collections[J]. Journal of Theoretical Biology, 1966, 13: 131-144..》Google Scholar
[48]
Wang S B. A question on the traditional biodiversity index[J]. Journal of Fudan University, 2003, 42(6): 867-868, 874. [王寿兵. 对传统生物多样性指数的质疑[J]. 复旦学报(自然科学版), 2003, 42(6): 867-868, 874.].》Google Scholar
[49]
Shen H B, Li R J, Lü B B, et al. Characteristics of fish community structure in the Weihe River of Shaanxi section[J]. Acta Hydrobiologica Sinica, 2019, 43(6): 1311-1320. [沈红保,李瑞娇,吕彬彬,等. 渭河陕西段鱼类群落结构组成及变化研究[J]. 水生生物学报,2019, 43(6): 1311-1320.].》Google Scholar