【作者】 张衡；

【导师】 陆健健；

【作者基本信息】 华东师范大学 ， 生态学， 2007， 博士

【摘要】 2004年9月～2007年9月笔者在长江河口(N30°30′～32°00′；E121°00′～122°30′)采用潮滩插网(主要采集潮间带鱼类)、深水张网、鳗苗网、大型浮游生物网、阿氏网等多种网具进行了104次湿地鱼类(—6m以浅水域)现场调查；首次较为全面地研究了长江河口湿地鱼类群落结构和主要生态特征。主要内容有：(1)归纳分析了长江河口湿地鱼类的物种组成及其主要生态特征；(2)运用如nMDS、等级聚类、ANOSIM、优势度曲线等生物统计学方法对获得的231份样本分析了潮间带和潮下带鱼类群落组成的时空变化及不同高程下潮间带鱼类的群落结构差异；(3)探讨了长江河口湿地鱼卵、仔稚鱼种类和丰度的空间分布和季节变化趋势，以及潮滩湿地作为鱼类产卵场和哺育场的重要性；(4)根据长江口历年鳗苗捕捞统计资料及现场调研数据，分析了鳗苗捕捞活动所产生的经济效益及对湿地鱼类的影响。主要研究结果如下：1．长江河口湿地鱼类群落区系特征(1)本研究发现长江河口湿地鱼类有123种，隶属18目、46科、98属，全部为硬骨鱼类。其中，海鲢(Elops saurus)和印度小公鱼(Sardinella sindensis)为本区域的新记录种，分别位于北支中段水域(2005年10月)和口门区(2006年9月)。长江河口南支水域共发现鱼类80种，北支有57种，口门区有70种。同时，研究结果认为长江河口湿地鱼类是河流淡水鱼类区系和海洋鱼类区系的过渡类型。(2)潮间带鱼类共记录有93种，隶属15目、33科，约占总调查种数的75％，充分说明潮间带湿地是河口地区鱼类重要的栖息生境。(3)本研究共记录到口门区潮下带鱼类42种，隶属21科。以偶然进入河口湿地的海洋鱼类最多，有17种；其次为河口定居种和季节性进入河口湿地的海洋鱼类，均为10种；而淡水类型和过河口性鱼类很少，均为1种。主要也由小型鱼类或较大个体鱼类的幼鱼为主。(4)长江河口湿地鱼类共有6种生态类型，主要为淡水鱼类(66种)、终生河口湿地鱼类(即河口定居种，35种)、季节性河口湿地一海洋鱼类(26种)、溯河洄游鱼类(6种)、降河洄游鱼类(3种)和临时性河口湿地一海洋鱼类(70种)；其中，8种鱼类兼具两种生态类群。前5种生态类群的鱼类种数约占总种数的三分之二。2、潮间带和潮下带湿地鱼类群落特征(1)长江河口潮间带湿地鱼类以小型鱼类或较大个体鱼类的幼鱼为主，约占总数的95％，成鱼较少出现在潮间带水域，体现了潮间带湿地对仔、稚、幼鱼的重要哺育作用。丰度—生物量曲线变化特征说明河口区潮间带鱼类群落主要以小型鱼类为主。由此可以证明，潮间带湿地是长江河口鱼类重要的育幼场。(2)聚类分析和非度量多维尺度分析相结合的方法证明潮间带鱼类组成显著分为两种群落类型，即口内淡水鱼类群落和口门咸、淡水鱼类群落。在季节变化上，春季鱼类的群落结构与夏、秋季差异较大，而夏季和秋季差异相对较小。在淡水区或咸淡水区，水温和鱼类丰度的相关系数较盐度稍高(淡水区：Spearmanr=0.023(水温)和0.022(盐度)；咸、淡水区：r=0.13(水温)和0.1(盐度))；而就整个河口鱼类群落来说，水温和鱼类丰度的相关系数较盐度低(r=0.03(水温)和0.46(盐度))。通过对河口低盐淡水区潮间带鱼类的昼夜、半月相和季节变化的研究发现，鱼类丰度的昼夜变化各个季节均有所差异，春季白天和夜晚潮水鱼类丰度无显著差异(t-test，P＞0.05)，而夏、秋、冬季存在显著差异(P＜0.05)。夏季夜晚潮水的鱼类丰度显著高于白天潮水(P＜0.05)，而秋、冬季则相反。从半月相的短时间尺度来看，春、夏和秋季各个潮序的鱼类丰度一般均大于冬季；小汛潮期，各个季节的平均种类数和平均丰度均小于其它汛潮期(t-test，P＞0.05)。从季节变化来看，鲫(Carassius auratus)、鳊(Parabramis pekinensis)、光泽黄颡鱼(Pelteobagrus nitidus)和斑尾刺虾虎鱼(Acanthogobius ommaturus)等几种鱼类都是季节性的出现在潮间带，且不同水深的鱼类丰度和体长分布存在一定的差异，这有助于降低种内、种间对食物资源的竞争，有利于幼鱼的肥育和生长。(3)口门区两站点的潮下带鱼类群落的种类组成和丰度差异不显著(ANOSIM，P=0.68)，而其时间结构存在一定的差异，主要是由于日本鳗鲡、棘头梅童、龙头鱼、刀鲚等17种河口或沿岸鱼类的季节性洄游特征所引起。3．鱼卵、仔稚鱼群落特征(1)本研究通过对南、北支水域的六次鱼卵、仔稚鱼调查共发现鱼卵、仔稚鱼36种(类)。在六次水平网调查中，河口淡水区站点均未采集到鱼卵，仅在河口咸淡水区(S9站点)采集到较多鱼卵；而仔稚鱼的分布规律不是十分明显。(2)长江河口湿地鱼卵、仔稚鱼群落结构复杂，近20年来数量丰度有所下降。目前，淡水区以麦穗鱼(Pseudorasbora parva)、银鱼科鱼类为优势种，咸、淡水区以风鲚(Coilia mystus)、小公鱼属、短尾大眼鲷(Priacanthus macrocanthus)等为优势种。1990年9月初和2006年9月下旬航次均采集到凤鲚的仔稚鱼，且前者的平均丰度约是后者的10倍；2005和2006年4月航次前颌间银鱼(Hemisalanx prognathus)的平均丰度为0.8个／网，低于1986年4～5月口门区的平均丰度14.5个／网。4．长江口鳗苗捕捞活动对河口湿地鱼类群落的影响鳗苗捕捞活动除了对鳗苗资源的严重破坏外，对兼捕渔获物资源也有较大的负面影响。本研究发现，鳗苗捕捞活动对刀鲚(Coilia ectenes)、凤鲚、棘头梅童(Collichthys lucidus)和红狼牙虾虎鱼(Odontamblyopus rubicundus)等种群负面影响较大。2006年仅3月份，整个河口刀鲚幼鱼就被捕捞45吨以上，凤鲚幼鱼或成鱼被捕捞31吨以上；2007年1～3月刀鲚和凤鲚分别被捕捞96.6吨和29.0吨。此是刀鲚等资源鱼类衰退的原因之一。更多还原

【Abstract】 This paper first comprehensively summarized the wetland fishes’ master list and their mainly ecological characters and filled up the blank of study on the estuary wetland fish in China, based on 104 surveys about wetland fishes (below -6m) from Sep., 2004 to Sep., 2007 and relatively historical data in the Yangtze estuary (N30°30’～32°00’; E121°00’～122°30’). The intertidal fishes were normally collected by tide stow net, while subtidal fishes collected by deep-water stow net, eel net, macro-plankton net, Agassiz trawl and so on. In total, there were 231 fish samples collected. The paper includes four parts, the first is summery on wetland environment, fish master list and its ecology characters; the second is study on the spatial and temporal changes of community structure of the intertidal and subtidal fishes used some biostatistics methods; the third is the research to species composition of fish eggs and larvae; the forth is the effect on wetland fishes from the traditional fishing eel activity. The main conclusions follow:1. Characters offish community and flora in the Yangtze estuary(1) Based on the different sample methods, we collected 123 fish species belongs to 1 glasse, 18 orders, 46 families and 98 genera in the Yangtze estuary. Among them, Elops saurus and Sardinella sindensis are 2 new recored fishes species which were found in the middle north branch (June, 2006) and esturine mouth (September, 2006). 80 fish species were found in the south brach, while 57 and 70 species in the north branch and esturine mouth, respectively. In conclusion, fish flora in the Yangtze estuary is transitional type between fresh river water and adjacent marine fish flora.(2) The intertidal fishes were collected 93 species belongs to 15 orders and 33 families, occupied about 75% by the total collected fishes. It indicated the intertidal flat was a kind of very important habitant for fishes in estuary area.(3) We also collected 42 subtidal fish species belongs to 21 families in the estuarine mouth. The number of fishes those occasionally entering estuary wetland is the highest (17 species), then those resident and seasonally entering estuary wetland followed (both 10 species), while the fresh water and diadromous fishes are the lowest (both 1 species). Similarly, small fishes or juvenile fishes of larger size are dominant in the subtidal water area in estuarine mouth. (4) From the fish ecological groups, there are 6 groups in the Yangtze estuary wetland, fresh water fish (66 species), resident species (35 species), seasonally entering estuary wetland species (26 species), anadromous species (6 species), catadromous species (3 species), and ocassionlly entering estuary wetland species (70 species). In them, 8 fish species have 2 kind of ecological groups. Two-thirds of fishes are highly depend on the estuary, because the fishes spend their largely or all life history in estuary wetland waters.2. Characters of intertidal and undertidal fish community(1) Small fishes or juvenile fishes of larger sizes are dominant in the intertidal flat and a little fishes spawn in this area, it means that only minority of adult or spawning fishes occur in the intertidal water areas. The k-dominance curves of individuals suggested the fish community had a certain extent disturbed by long over-fishing and other anthropic activities. This paper richly approve that intertidal flat is nursey field in the Yangtze estuary.(2) Two community types were obviously divided in the intertidal fishes by CLUSTER and nMDS analyze methods, namely fresh water and brackish water fish communities. In seasonal changes, fish community structure in spring largely differ that of summer or autumn, but that of summer is relatively less differ from autumn. Temperature and salinity are two main factors affected the spatial and temporal changes of intertidal fish community. Temperature mainly affects the temporal change, because the spearman r of tempertuare are 0.023 and 0.13 in freshwater and brackish water, respectively; which higher than 0.022 and 0.1 of sanlinity. Salinity mainly affects the spatial change of fish community structure, because the salt endurance of different ecological groups of fishes decides them live in different waters in the estuary.We also studied the diel, semi-lunar and seasonal changes of fish abundances in Chong-xi intertidal flat. The results showed that the abundance in night tides is significant higher than day tides (P<0.05), but contrary to autumn and winter (P<0.05). These differences mainly caused by different tidal height. In a semi-lunar cycle, the fish species and abundances in spring tides both higher than that in neap tides (Mest, P>0.05) . From the seasonal change, many fishes occur in the intertidal flat seasonally, such as Carassius auratus, Parabramis pekinensis, Pelteobagrus nitidus, Synechogobius ommaturus, while the abundances and body-size distribution in different water depth have some extent differences in favor of juvenile fishes’ growth and deceasing inter or intra food competition.(3) There was no significant difference of fish abundance between 2 sations in the subtidal fish community in the estuarine mouth (ANOSIM, P=0.68), but exite some extent difference in the temporal structure. The greater contribution on the fish community were 17 fish species, such as Anguilla japonica, Coilia ectenes, Harpodon nehereus and Collichthys lucidus, ans so on.3. Characters of ichthyoplankton community(1) Based on the data at 6 surveys in the South and North branch waters, it showed that the total number of species of eggs and larvae was 36. Eggs were not collected in fresh waters and only collected in S9 station at estuary mouth in 6 surveys. There is not clearly disciplinary in distribution of larvae.(2) The dominant species vary much in each survey, this reflect that the community structure of ichthyoplankton is complicated. The the abundance of larvae and juveniles has some extent declined in nearly 20 years. In fresh water, the dominant species are Pseudorasbora and Salangidae; while those are Coilia mystus, Anchoviella, Priacanthus macracanthus. We both collected the Coilia mystus larvae in early Sep., 1990 and latterly Sep., 2006, while the abundance of former was about 10 times than the latter. The average abundance of Hemisalanx prognathus was 0.8 ind./net, which was obviously lower than 14.5 ind./net in April-May, 1986.4. Effect on the fish community of eel fishing activity in the Yangtze estuary The traditional fishing eel activity one hand damage the population of Japaneseeel; on the other hand, heavily destroy the resources of other wetland fishes, such as Coilia ectenes, Coilia mystus, Odontamblyopus rubicundus, and Collichthys lucidus. The total catch of Coilia ectenes juveniles was above 45 and 96.6 tons in Mar., 2006 and from Jan. to Mar., 2007, respectively, which above 31 and 29 tons of Coilia mystus. Hence, the heavily decreasing population of Coilia ectenes and other fish resources were mainly affected by the fishing activity.更多还原