高邮湖鱼类群落结构特征

为了解高邮湖鱼类群落结构特征,采用三层刺网和单目地笼网鱼类采样工具,于2019-2020年在该湖泊设置的5个点位进行4次调查,鉴定了渔获物种类,分析了鱼类生态类型和群落结构特征指数。结果显示:高邮湖鱼类24种,隶属20属7科6目。淡水性、肉食性和中上层鱼类为优势生态型。鲫(Carassius auratus)、大银鱼(Protosalanx hyalocranius)、鳙(Hypophthalmichthys nobilis)、黄颡鱼(Pelteobagrus fulvidraco)、刀鲚(Coilia nasus)和鲢(H.molitrix)为高邮湖优势种。平均Shannon-Wiener多样性指数为1.45,Pielou均匀度指数为0.61,Simpson优势度指数为0.6,Margalef种类丰富度指数为1.91。与历史资料相比,鱼类群落多样性和丰富度指数有所提高,但群落结构受干扰程度较高。Cluster聚类和nMDS平面图显示,高邮湖不同空间的鱼类多样性差异较小;而与其北部入湖口河流水域相比,鱼类群落结构差异显著。过水性高邮湖的鱼类多样性高于河道,但总体上鱼类物种多样性处于较低水平。     

洪湖自然保护区浮游生物空间分布及与水质关系

研究围垸养殖对洪湖自然保护区水质的影响,从浮游生物视角评价水质现状及发展规律,以期为洪湖自然保护区科学管理及水生态修复提供基础数据。2019年6月在洪湖自然保护区不同方位水面布设10个采样点,开展水质及浮游动植物现状调查和分析,计算生物多样性,并与环境因子做CCA分析。调查共检出浮游植物6门57属74种,以蓝藻门的微囊藻、硅藻门的颗粒直链藻、绿藻门的单角盘星藻为主要优势种;浮游动物61种,以萼花臂尾轮虫和广布中剑水蚤为主要优势种。浮游植物Shannon-Wiener生物多样性指数均值为2.26,浮游动物均值为2.12,水质为中度污染状态,但有重度污染的趋势。CCA分析表明,浮游植物分布与SD呈正相关,与WT、COD;等呈负相关;部分轮虫及大部分原生动物与SD、As呈正相关,与WT、Chl-a等呈负相关。洪湖自然保护区水体处于中富营养型状态。围垸养殖会导致洪湖水体有机物沉积、水质恶化,并对浮游生物种类组成和数量产生重要影响。     

Length-based Beverton and Holt spawning stock biomass per-recruit-models, with application to the Lates stappersii (Boulenger) stock in Lake Tanganyika

Two kinds of length-based Beverton and Holt spawning stock biomass per-recruit ( SSB/R )-models are presented. The first allows the computation of the absolute value of SSB/R . The second estimates the index of SSB/R , also called 'relative SSB/R '. Both models are extensions of the original age-based Beverton and Holt SSB/R -models. The SSB/R and its index can be assessed with reference to variations in the exploitation characteristics. These models were applied to the Lates stappersii (Boulenger) stock in Lake Tanganyika using fishing mortality as the independent variable. They produce an absolute value of SSB/R of 12.95 g, representing 22.4% of that of the 'virgin' stock for the 1993–1994 equilibrium-fishing regime. This level is indicative of an unsafe state of the stock in question. Moreover, the SSB for L. stappersii seems to be fragile under increased fishing pressure as, for example, doubling or tripling the current fishing regime would reduce the current SSB/R by 57.3 and 77.4%, respectively. In general, the use of length-based Beverton and Holt SSB/R -models is handicapped by underlying hypotheses and sub-models which are restrictive.     

镜泊湖细鳞斜颌鲴的年龄与生长

本文报道了镜泊湖细鳞斜颌鲴的年龄生长特点。以鳞片上的年轮作为年龄鉴定依据。渔获物中1~+龄和2~+龄个体占52％以上,体长以14～26厘米为主。体长与鳞长之间呈直线相关L=0.1116+47.8754R。体重与体长呈指数函数相关 W=0.014L~(3.0?7?)。3~+ 龄以前生长较快,生长指标高,体长和体重的相对增长率大,以后转入成鱼生长阶段,其生长规律适合 von Bertalaffy 方程:L_t=38.5[1-e~(-0.328(t+0.446)];W_t=893.6[1-e~(-0.328(t+0.446)]~3。体重生长曲线的拐点位于 2.93龄的 W_t=0.32W_∞处,为成熟拐点。建议捕捞 3龄以上个体,并作为养殖对象加以发展。     

青肯泡浮游生物及鱼产潜力

青肯泡浮游生物共计1 1 3个种属,其中浮游植物63个种属,浮游动物5 0个种属,浮游植物数量2 37 .2 8×1 0 4 ind /L ,生物量2 5 0 0mg/L ,浮游动物数量5 5 0 5 .4ind /L ,生物量6 .692mg/L ,全库总鱼产潜力5 2 7760kg ,总放养量2 80 4 80 0尾。     

后官湖浮游生物群落结构特征及其环境驱动因子

为了了解后官湖国家湿地公园水生态环境现状,于2020年1月至12月对后官湖的水质、浮游植物和浮游动物进行了监测。结果表明后官湖西部湖区的总磷、高锰酸盐指数最高,是后官湖的主要污染来源。综合营养状态指数TLI(Σ)评价表明后官湖属于中营养状态,Shannon-Weaver指数和Pielou指数结果显示后官湖总体上为轻度污染到中度污染状态。调查期间共检出7门54属浮游植物,其中1月和4月主要以绿藻门和隐藻门占优势,5月至12月则以蓝藻门占优势。5月、9月-10月桡足类在浮游动物群落中占优势,其他月份则是轮虫类占优势。相比于2017年-2019年,2020年后官湖的营养状态水平和浮游植物丰度出现了明显的下降,而大型浮游动物在群落中的比例则明显上升。Spearman相关分析和冗余分析表明影响后官湖浮游植物群落的主要环境驱动因子为水温、透明度和浮游动物丰度。后官湖环境管理的不断加强和新冠疫情导致的流域内人类活动的减弱可能是后官湖2020年水生态环境质量明显提升的原因。     

淀山湖鱼类群落结构多样性的年际变化

淀山湖是上海市内陆水域最大的淡水湖泊,主要的淡水渔业水域和水产品来源地,也是重要的水生生物保护基地。为了评估增殖放流和生态环境变化对淀山湖鱼类群落结构变化的影响,本研究以2010-2012年淀山湖的渔业调查资料为基础,对该湖泊的鱼类优势种组成和多样性指数进行年际变化分析,并应用丰度生物量曲线方法对该湖的鱼类群落状况进行分析。结果表明:2010-2012年淀山湖鱼种类数基本稳定,基本鱼种组成变化不显著,优势鱼种组成趋势渐以小型鱼类为主;群落结构多样性指数年间差异不显著(P0.05);ABC曲线显示2010-2012这三年淀山湖群落的数量优势度曲线均高于生物量的优势度曲线,鱼类群落结构仍处于严重干扰状态。因此,建议改善增殖放流鱼种和加强渔业管理,以维持淀山湖鱼类群落的稳定。     

山东省东平湖轮虫种类组成研究

在东平湖设６个采样点，分别于枯、丰及平水期采样调查，共获轮虫５２种，隶属３亚目１０科２６属，其中４７种为东平湖轮虫记录，整个轮虫群落中，优势种１５种，普通种２４种，偶见种１３种，平均密度６８８个／Ｌ，调查结果表明，东平湖受到不同程度污染，属富营养型湖泊。     

Australia‘s Lake Eacham rainbow fish: lessons and outlook

Recent DNA comparisons confirm that the endangeredLake Eacham rainbow fish (Melanotaenia eachamensis Allen andCross, 1982) is a separate species, distinct from othermelanotaeniids in the area. Although the large populationformerly in Lake Eacham has not been re-established, other smallnatural populations of M. eachamensis have been identified fromLake Euramoo and Dirran Creek.Commencing with 23 captive individuals (3 14 6 I), representing three original stocks, Project Eachamensis (initiated by the Australia New Guinea Fishes Association in July 1987) has stimulated and actively encouraged the establishment of new captive populations. Approximately 15 captive breeding populations are now reported in eastern Australia -- numbers of individuals are estimated to exceed 1000; additional Bowman and Tappin populations are being maintained in North America and Europe.A recent review of this conservation programme (involving individual aquarists, hobbyist organizations and scientists as well as the aquarium industry and government) has now recommended: an alteration to the conservati on status category from endangered to vulnerable; maintenance of existing captive populations; formulation of a comprehensive recovery plan with the long-term objective of re-establishing and increasing natural populations; and encouraging public education on the risks of translocation.