黑龙江中游底层鱼类群落结构及多样性

2010—2011年采用定置网具和底层挂网对黑龙江中游底层鱼类进行调查。结果表明:采捕底层鱼类7目12科33属47种,其中外来移植鱼类1种,为湖拟鲤,列入《中国濒危动物红皮书.鱼类》的鱼类为施氏鲟、鳇、日本七鳃鳗和雷氏七鳃鳗4种;鲤形目种类最多,为31种,占调查物种总数的65.96%;黑龙江中游底层鱼类平均密度为139.00ind.m-3,平均生物量为344.58g.m-3;鱼类生态类型以河湖性和杂食性种类为主,群落优势种为兴凯鱊、光泽黄颡鱼、麦穗鱼、纵带鮠和银鲴等鱼类,优势种类中除鲇外,其他种类平均体重均小于30g;黑龙江底层鱼类群落的物种丰富度(D)、多样性指数(H’)和均匀度(J’)各断面均偏低,并存在一定程度的差异;黑龙江中游水质优良,大部分时期处于Ⅱ类水质以上水平,各断面鱼类种群多样性与营养盐及透明度等环境特征相关关系不明显,仅发现HW’与铵态氮和总氮呈显著正相关。     

气候变化对中国近海8种中上层鱼类潜在生境分布的影响

随着底层和近底层渔业资源的衰退,海洋中上层鱼类在我国海洋捕捞业中逐渐占据重要的地位。预测气候变化情景下中上层经济鱼类的潜在生境分布及其变化规律,可为应对气候变化的鱼类栖息地保护和渔业生态系统管理提供重要科学依据。采用物种分布模型模拟并预测现状及2050年两种气候变化情景下8种中上层经济鱼类在中国近海的潜在分布,通过分布区的收缩-扩张情形和质心迁移距离定量分析气候变化对鱼类空间分布格局的影响。结果表明：(1)模型预测结果良好,各组模型的AUC值均高于0.85,影响目标鱼类潜在分布的主要驱动因子为海水表层温度和溶解氧;(2)8种中上层经济鱼类中,羽鳃鲐(Rastrelliger kanagurta)、鳓鱼(Ilisha elongata)等种类生境分布偏南,气候变化情景下分布北界可扩展至长江口,而鳀鱼(Engraulis japonicus)、青鳞小沙丁鱼(Sardinella zunasi)等种类主要分布在我国北方海域,气候变化情景下生境南缘边界退缩明显;(3)整体来看RCP8.5情景下的空间分布变化率大于RCP2.6情景,其中蓝圆鲹(Decapterus maruadsi)、青鳞小沙丁...     

长江江豚重要栖息地清节洲水域鱼类群落结构

长江清节洲水域是长江江豚的重要栖息地之一,为了解该水域鱼类群落结构特征,于2017年4月、7月、10月和2018年2月对该水域鱼类群落进行了季节性调查。调查共采集鱼类38种,隶属于5目8科29属,其中鲤科鱼类占优势,占总种类数的68.4%。相对重要性指数结果显示鱼类群落优势种为贝氏?（Hemiculter bleekeri）、似鳊（Pseudobrama simony）、银鲴（Xenocypris argentea）和刀鲚（Coilia nasus）。按生活习性划分,定居性鱼类占绝对优势,占总种数的78.9%;在空间上,中上、中下和底层鱼类分布较为均衡,占总种数的比例依次为36.8%,28.9%和34.2%;从食性上划分,杂食性和肉食性鱼类较多,分别占总种数的44.7%和39.5%。Shannon-Weiner指数、Simpson指数、Margalef指数和Pielou均匀度指数依次分别为0.820~1.711,0.601~0.981,1.640~3.423和0.249~0.592。单因素方差分析表明,除春夏季与秋冬季的Margalef指数存在显著性差异（P<0.05）,各指数在时间和空间均无显著性差异（P>0.05）。与历史资料相比,该区域鱼类群落呈现物种多样性降低和群落结构小型化的趋势。因此,建议加强该水域鱼类资源的监测和保护,以维护长江生态系统的稳定与江豚栖息地的适合度。     

连江鱼类群落多样性及其与环境因子的关系

目前连江梯级开发至12级,为了解梯级开发后连江鱼类群落状况,于2009年3月和2010年4月对连江上、中、下游7个代表江段的鱼类群落结构以及环境因子分别进行了调查,共采集鱼类98种,分属于9目20科75属。海南墨头鱼Garra pingi hainanensis、南方长须鳅鮀Gobiobtia longibarba meridionalis为连江新纪录种。银鮈Squalidus argentatus、黄颡鱼Pelteobagrus fulvidraco、小鳈Sarcocheilichthys parvus、马口鱼Opsariichthys bidens、餐Hemiculter lecuisculus等小型鱼类在鱼类群落结构中占优势地位。对鱼类群落进行聚类分析(CLUSTER)和非度量多维标度排序(NMDS)分析结果表明连江鱼类被划分为3个类群,即下游河口类群、中下游类群及中上游类群;S2、S3两个站位鱼类物种多样性(H’)、丰富度(D’)和均匀度(J’)均高于其他站位。通过对连江各站位鱼类群落与环境因子的典型对应分析发现:河宽、温度、海拔、pH值和水坝之间的距离5个因子与鱼类群落相关性较强(P<0.05)。与历史资料对比后发现,连江鱼类种类、分布、生态类型都发生了巨大变化。     

长山列岛邻近海域鱼类群落种类组成和多样性时空变化

为了解黄、渤海生态系统交错带长山列岛邻近水域鱼类群落种类组成和多样性,根据2016年10月,2017年1月、5月及8月进行的鱼类资源底拖网调查数据,应用相对重要性指数、物种多样性指数、k优势度曲线等方法,研究了长山列岛邻近海域鱼类群落种类组成、物种多样性时空变化及其与环境因子的关系。结果表明: 该海域共计捕获鱼类77种,以温水性、底层、洄游性鱼类为主,优势种组成季节变化明显,春季、冬季主要优势种为黄鮟鱇,夏季以日本鲭、鳀等中上层鱼类为主。全年共计出现洄游性鱼类46种,季节间物种迁移指数均在100以上,其中秋季物种迁移指数最大。鱼类群落物种丰富度指数在春季最高、Shannon多样性指数和均匀度指数在秋季最高。夏季物种丰富度指数与表层水温呈显著负相关;冬季物种丰富度指数与水深、底层水温呈极显著正相关,Shannon多样性指数与底层水温呈极显著正相关。长山列岛邻近海域作为黄、渤海两大生态系统的交错带,鱼类群落表现出高物种多样性、洄游种多以及明显的时空异质性。     

基于随机森林模型预测气候变化对黄颡鱼适生区的影响

作为对温度等相关环境条件要求较高的温水性鱼类, 全球气候变化引起栖息水域环境的改变可能会对黄颡鱼(Pelteobagrus fulvidraco)自然资源的分布产生影响。研究基于黄颡鱼物种分布信息、WorldClim气候数据(BCC-CSM1-1、CCSM4和MRI-CGCM3气候变化模型以及RCP2.6和RCP8.5温室气体排放情景)与集成学习算法随机森林(Random forest)对黄颡鱼当前、2050s和2070s潜在栖息地进行预测。所研究结果表明: (1)预测模型的Area Under the Curve (AUC)高达0.971, 指示模型的泛化能力较好, 结果可靠性较高; (2)结点纯度(Node purity)评判表明平均温度日较差和最暖季度降水量是预测黄颡鱼潜在分布的最重要环境因子; (3)在未来气候变化条件下, 黄颡鱼的栖息地中心逐渐脱离我国的东部和中部等地并北移, 且其高适生区面积逐渐减少。就黄颡鱼潜在栖息地以及影响其分布的主要生态条件进行相关研究, 对于黄颡鱼种质资源保护区的划分、渔业管理和潜在的生物入侵防控具有现实意义, 并可为东亚地区其他淡水鱼类应对气候变化的响应提供参考依据。     

葛洲坝下游江段中华鲟产卵场食卵鱼类资源量估算

为定量评估食卵鱼类对中华鲟资源的危害,1997－2001年间,对中华鲟产卵场所在的葛洲坝水利枢纽坝址至下游庙嘴之间长约5km的江段,进行了渔业捕捞样本抽样和解剖检测,运用体长股分析方法并结合淦获物中不同种类的相对数量比例估算出食卵鱼类资源量,研究结果表明,吞食中华鲟卵的主要有圆口铜鱼,铜鱼,瓦氏黄颡鱼等11种鱼类,其年度资源量为197487－744487尾,多年平均444822尾。     

泉州湾海域鱼类多样性及营养级变化

利用2008年5月和10月在泉州湾进行的拖网渔业资源调查资料, 探讨了该海域鱼类群落结构和物种多样性特征。结果表明, 两次拖网调查共鉴定鱼类54种, 隶属于2纲13目32科。其中中上层鱼类12种, 近底层鱼类19种, 底层鱼类23种; 暖水性鱼类40种, 暖温性鱼类14种, 未发现冷温性和冷水性种类; 杂食性鱼类4种, 低级肉食性鱼类37种, 中级肉食性鱼类8种, 高级肉食性鱼类5种。白姑鱼(Argyrosomus argentatus)和叫姑鱼(Johnius belengerii)是5月份最主要的优势种, 凤鲚(Coilia mystus)和龙头鱼(Harpodon nehereus)是10月份最主要的优势种。与1985年的调查资料相比, 泉州湾鱼类组成和优势种发生了很大的变化, 多样性指数由3.05下降到2.32, 均匀度指数由0.76下降到0.58, 营养级指数由2.79下降到2.54。泉州湾鱼类多样性下降的主要原因可能是过度捕捞、水域污染和栖息地丧失等。     

长江口中华鲟自然保护区底层鱼类的群落结构特征

根据2004年8月、11月和2005年2月(Ⅰ年度)、2005年8月、11月和2006年2月、5月(Ⅱ年度)、2007年8月、11月和2008年2月和5月(Ⅲ年度)对长江口中华鲟自然保护区15个站位点的底拖网调查数据,对该水域的底层鱼类群落结构特征及时间和空间变化规律进行了分析。结果表明,调查中捕获底层鱼类42种,隶属于13目24科39属。底层鱼类的种类组成和群落结构进行聚类分析,15个站位聚合成两大类群,类群A位于南支北港和北港北沙近东滩水域,共出现20种底层鱼类,主要以淡水性和河口性鱼类为主;类群B位于北支和北港北沙近外海水域,共出现鱼类39种,主要以河口性和海洋性鱼类为主。ANOSIM和SIMPER分析表明底层鱼类群落结构不同季节间差异显著,造成这种趋势的主要原因可能是与棘头梅童鱼(Collichthys lucidus)和凤鲚(Coilia mystus)的繁殖和索饵洄游有关。     

三峡水库光泽黄颡鱼年龄、生长与死亡特征研究

光泽黄颡鱼(Pelteobagrus nitidus Sauvage et Dabry)是三峡水库蓄水后的优势中小型底层鱼类之一,为解析其种群特征,基于2015—2016年在三峡水库采集的鱼类样本(n=2477),对其年龄与生长等进行了研究.光泽黄颡鱼的平均体长为(87.1±0.5)mm,不表现雌雄异形.库尾种群的平均...     

安庆西江长江江豚迁地保护基地河岸带植物群落结构特征

安庆西江是长江下游唯一的长江江豚(Neophocaena asiaeorientalis)迁地保护区。为了解安庆西江河岸带植物群落结构, 进而评价西江长江江豚栖息地的生境情况, 于2017年夏季对西江河岸带10个断面的植被进行了系统调查。研究结果表明, 西江河岸带植被中共有维管植物166种, 隶属于50科131属, 其中藻类植物1科1属1种, 蕨类植物1科1属2种, 种子植物48科129属163种, 以蝶形花科、菊科、禾本科为优势科, 科、属的分布类型较为丰富。对植物群落结构分析的结果显示, Shannon-Wiener指数变幅为0.213—0.899, 均值为0.629±0.399; Simpson指数变幅为0.135—0.465, 均值为0.315±0.204, 物种丰富度变化范围在3—14, 多样性指数与丰富度指数变化一致。西江河岸带植被分布还呈现出显著的空间特征, 两岸受人类活动影响较大的区域, 河岸带植被多样性指数较低; 自然区域的植物覆盖面积大, 群落多样性指数和丰富度则较高。总体而言, 西江河岸带植被物种丰富, 覆盖率高, 既可以改善水质, 又可以为小型定居性鱼类提供良好的产卵场和索饵场, 对于维持长江江豚迁地种群的栖息和繁衍生境具有重要意义。     

长江江豚细菌性疾病的诊治

人工饲养或易地保护长江江豚(Neophocaena asiaeorientalis asiaeorientalis), 其水体中常含有病原菌且易引起江豚发病, 探讨长江江豚的细菌性疾病诊疗方法十分必要。文章利用细菌的分离培养与鉴定, 结合血液检测结果, 对安庆西江围网内一头患病江豚进行了病原确诊, 结果发现患病江豚的致病原为金黄色葡萄球菌(Staphylococcus aureus)和魔氏摩根菌(Morganella morganii)。依据致病菌的药敏试验结果, 综合患病江豚的整体状况制定了治疗方案并对其进行系统治疗, 结果预后良好。研究的成功开展为江豚、海豚等鲸类动物细菌性疾病的诊断与防治提供了良好借鉴。     

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

Information on the habitat use of the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critical for its conservation. The diel biosonar behavior of the porpoise in the port areas of the Yangtze River was examined along with simultaneous observations of fish density and boat traffic. Biosonar pulses from the porpoises were detected for 1233 min (5.77%) over a 21,380 min duration of effective observations. In total, 190 (5.63%) buzzes (an indication of prey capture attempts) were recorded among the 3372 identified click trains. Of the 168 echolocation encounters (bouts of click trains less than eight min apart), 150 (89.3%) involved single animals, indicating that solitary porpoises were frequently present and feeding in the port areas. Significant diel patterns were evident involving the biosonar behavior of the porpoises (including click trains and buzzes), fish density and boat traffic. The frequencies of the click trains and buzzes were significantly lower during the day than in the evening and at night, which suggests that porpoises in this region are primarily engaged in crepuscular and nocturnal foraging. The lack of a significant diel pattern in the echolocation encounters indicates the importance of the port in porpoise conservation. A forced feeding schedule may be associated with the lack of a significant correlation between porpoise acoustics and boat traffic. Overall, prey availability appears to be the primary factor that attracts porpoises. Additionally, porpoises tend to migrate or remain downstream in the morning and migrate or remain upstream in the evening, most likely to follow their prey. The findings of this study can be used to improve the conservation of the Yangtze finless porpoise.     

固化河岸对长江江豚栖息活动的影响

长江江豚主要栖居在近岸浅水水域,喜好泥沙质类型的河岸。但在长江干流,有很多自然河岸被固化,河岸固化给长江江豚分布和栖息活动造的影响仍不甚清楚。2016年3月—2017年1月,对长江干流2个自然河段江豚的数量和分布做了12次考察,并收集了这2个河段岸型的相关数据,来分析固化河岸对江豚栖息活动的影响。12次考察累计发现江豚215头次,平均每次考察观察到江豚(17.92±7.09)头次。研究区域的固化河岸约占岸线总长的59%,分析发现,仅约13.9%的江豚分布在固化河岸水域,86.1%的江豚均分布在自然河岸水域。江豚在单位河岸长度的分布数量与该段固化河岸长度所占的比例呈显著负相关(r=-0.639,P0.01)。在自然河岸,分布在近岸50 m水域的江豚占31.8%,而在固化河岸,仅观察到2头江豚活动在近岸50 m水域内。由此可见,固化河岸对江豚的近岸分布有明显影响。调查还发现,安庆城区建设带约10 km江段12次考察均未发现江豚分布,城区建设带可能对江豚栖息已造成严重影响。长江干流的固化河岸所占比例非常高,研究结果提示这可能导致长江干流江豚栖息地的丧失和破碎化加剧,在制定长江江豚保护措施必需慎重考虑此因素的影响,并据此提出相应的栖息地保护和恢复方案。     

Seasonal changes in the local distribution of Yangtze finless porpoises related to fish presence

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is an endangered freshwater porpoise subspecies unique to the Yangtze River basin. Seasonal variations in local distribution of the animal, as well as fish presence, sand dredging, ship navigation, and bridges were examined as potential factors affecting the occurrence of the animals. Passive acoustic surveys were performed regularly from May 2007 to August 2010, near the conjunction of the Yangtze River and Poyang Lake. The distribution of the porpoises was seasonally site‐specific. In May and August, the animals were detected more often at river junctions than in the lake, but vice versa from November to February. The rate of the porpoise detection was significantly higher in areas of fish presence than in areas of absence. The number of porpoises detected did not differ significantly between the sand dredging operation and the prohibition period (in 2008), although the number of vessels obviously declined in 2008. Ship traffic and bridges also did not appear to affect the presence of porpoises. These results showed the relative importance of the various environmental factors, which is important for conservation of not only Yangtze finless porpoise but also endangered isolated cetaceans.     

Distribution and breeding biology of offshore pelagic cyprinids and catfish in Lake Malawi/Niassa

Synopsis Lake Malawi/Niassa is a permanently stratified lake, consisting of an oxygenated layer of 230 m depth that overlies an anoxic zone that extends to the lake bottom at a maximum depth of over 700 m. Some fish are found throughout the oxygenated zone of the offshore waters, and lead a pelagic existence, although many of the species form part of the demersal community in shallower waters where the lake-bed is oxygenated. This paper reports on the distribution of cyprinids and catfish at six offshore locations, sampled with a mid-water trawl and gillnets, along the north-south axis of the lake. These two groups formed, respectively, 5% and 13% of the offshore fish biomass in the trawl catches. The offshore cyprinids comprised the small lake-spawningEngraulicypris sardella, the only species to have pelagic larvae, and the larger river-spawningOpsaridium microcephalum andO. microlepis. These cyprinids occurred mainly in the upper 100 m of the water column. The biomass of both larvae and adults ofE. sardella showed considerable fluctuations over the two years of study. The spawning site ofE. sardella remains a mystery, but is no longer believed to be in the offshore pelagic zone. The most abundant catfish was the mochokidSynodontis njassae, that exhibited diurnal movements from just above the oxic-anoxic boundary layer during the day to the surface layers at night. The clariid catfish of the genusBathyclarias were caught infrequently offshore, but owing to their large size, they could form a significant part of the biomass. Their abundance was difficult to quantify, as it was believed that the majority are active in the near-surface layers and were under-sampled by the trawl and gillnets. Information on some aspects of the breeding biology is included in the paper, although our knowledge in this area is very incomplete.     

不同流态中长江江豚的栖息活动比较

长江江豚(Neophocaena asiaeorientalis)呈斑块状分布在长江干流,对栖息地有明确的选择性.流态是栖息地水文环境的核心内容.为研究长江江豚对不同流态的选择性,本文根据1993-2021年对长江下游15次样线考察记录到的412次,合计1 117头江豚个体的栖息活动进行了统计分析.结果表明:全年长江江...     

Community structure of deep-sea demersal fish in the North Aegean Sea (northeastern Mediterranean)

The spatial structure and seasonal changes of the demersal fish assemblages on the continental shelf (100–200 m) and upper slope (200–500 m) in the North Aegean Sea (Northern Aegean and Thracian Seas, northeastern Mediterranean, Greece) were analysed. Seasonal experimental trawl surveys, carried out from summer 1990 to autumn 1993, provided a total of 151 demersal fish species. Analysis of 259 bottom trawls showed the existence of four groups associated with the continental shelf and the upper slope; each group was dominated by a small number of species. The bathymetric distribution of the species, established using measures of the centre of gravity and habitat width, revealed that most of the species had a wide distributional range within the study area, although a few were restricted to the greatest depths. Density, biomass, species richness and diversity decreased significantly with depth, and were also indicative of distinctive characteristics between these fish assemblages. Mean fish weight exhibited two different trends: a bigger-deeper phenomenon at the continental shelf and a smaller-deeper phenomenon at the upper slope. The variability in assemblage structure was determined mainly by depth and, to a lesser extent, by season and geographical location. For some species, results suggest a pattern of gradual species replacement along the depth gradient coupled with ontogenetic habitat shifts.     

长江东流河道整治对长江江豚种群数量的影响

长江江豚是生活在长江中下游的濒危水生哺乳动物,通常活动在江心洲和浅水缓滩附近。航道整治改变了鱼类栖息活动的水文环境,也给豚类生存带来负面影响。本文根据长江东流河道整治施工前和施工后各3 次野外考察资料,分析了3 种流态中江豚的数量与群结构。结果表明,该工程实施前江豚主要栖息活动在边滩的分离区,其次在洲头的分流区。工程实施后,整治江段的江豚种群数量年下降率达8. 9% 。江豚在分流区活动已消失,在分离区集群规模较小,且在流态之间移动增大。本文研究结果也提示长江江豚就地保护难度越来越大,从长江干流中把长江江豚迁入故道中是一件刻不容缓的工作。     

长江安庆段航道整治对长江江豚数量和分布的时空影响

栖息地丧失和破碎化是威胁长江江豚(Neophocaena asiaeorientalis)种群长期发展的主要因素之一。航道整治工程是导致江豚栖息地丧失和破碎化的一个主要原因,研究工程施工和运行对江豚数量和分布的影响可为江豚栖息地管护提供有益信息。通过对湖口-吉阳矶水域江豚数量和分布的持续调查,分析了安庆段航道整治工程施工和运行对江豚的影响。12次目视调查共在研究水域发现江豚258群次613头次,工程施工前、施工期和初步运行期单次考察分别平均观察到江豚(67.0±24.3)头次、(35.6±22.2)头次和(50.0±2.8)头次。在主要施工区共发现江豚79群次185头次,施工前、施工期和初步运行期单次考察分别平均观察到江豚(18.60±12.03)头次、(10.4±7.3)头次和(20.0±4.2)头次。工程不同时期主要施工区江豚的数量及占比在统计学上没有显著差异。主要施工区S2和S3工程段施工期江豚平均分布密度((0.18±0.17)头/km、(0.04±0.08)头/km)较施工前((0.62±0.16)头/km、(0.40±0.29)头/km)显著下降,S5和S6工程段施工期平均...