冰封期乌梁素海浮游植物生态位和种间联结性分析

为了解乌梁素海冰封期浮游植物群落结构和生态位特征，于2018年和2019年冬季（1月）进行浮游植物采样调查。根据乌梁素海污染源分布、水文及环境特征，在湖泊入水口（N1~N6）、湖泊中部（N7~N14）和湖泊出水口（N15、N16）选取了16个典型样点，进行浮游植物和水样采集；运用改进的Levins公式和Petraitis指数测定浮游植物优势种的生态位宽度和生态位重叠度。结果表明，2018年和2019年冰封期共鉴定出浮游植物优势种2门6种和6门8种，伪鱼腥藻是2018年的绝对优势种，2019年的绝对优势种为蓝隐藻和旋转囊裸藻。2018年冰封期优势种生态位宽度为0.0711~0.5971，宽度最大的为球衣藻，其次是绿柄球藻和衣藻；2019年冰封期优势种生态位宽度为0.1265~0.5455，宽度最大的为绿柄球藻，其次是具尾逗隐藻和蓝隐藻。2018 年和2019年乌梁素海冰封期各优势种的生态位重叠值分别为0.0078~0.7967 和0.0448~0.9248，整体上重叠值小；2018年冰封期浮游植物优势种绿藻门的衣藻与球衣藻的重叠值最高，2019年隐藻门的具尾逗隐藻与蓝隐藻的重叠值最高。生态位重叠度和生态响应速率显示，2018年乌梁素海冰封期浮游植物群落整体上呈发展趋势，而2019年呈衰退趋势。方差比率法分析显示，优势种整体呈正关联；卡方检验发现，各优势种间的联结性均不显著，大多数藻类种间为负关联，少数为正关联。     

西藏巴松错（湖）夏季浮游植物群落的水平和垂直分布

为揭示西藏巴松错浮游植物群落结构的水平和垂直分布特征及其与环境间的关系，于2020年7月对巴松错出入河流及其湖体15个采样点和湖中心B15采样点11个分层的浮游植物进行了调查，同时测定了水体相关理化指标。调查共采集水样275个，分析了浮游植物物种组成、细胞丰度、生物量和物种多样性等群落结构特征，并探讨浮游植物对水平和垂直环境梯度变化的响应。结果表明：（1）巴松错夏季共鉴定浮游植物167种，隶属于5门8纲20目29科66属，物种组成为硅藻-绿藻-蓝藻型；（2）在水平方向上，平均细胞丰度为1.8453×104 cells/L，平均生物量为0.0117 mg/L；在垂直方向上，平均细胞丰度为1.0055×104 cells/L，平均生物量为0.0061 mg/L；（3）巴松错夏季浮游植物群落结构水平分布较为均匀，群落复杂程度相对较高，较垂直分布更稳定；（4）RDA分析结果表明，EC是影响巴松错夏季浮游植物水平群落变异的主要环境因子，TUR是影响垂直变异的主要环境因子。本研究结果为进一步研究高寒湖泊生态系统提供了基础资料。     

西藏色林错-普若岗日国家公园潜在建设区夏季浮游植物群落生态特征

为了探究色林错-普若岗日国家公园潜在建设区夏季浮游植物群落及优势种生态特征,于2015年和2016年8月对浮游植物群落进行了调查分析,并运用生态位宽度、生态位重叠及生态响应速率等方法测定优势种的生态位量度。结果表明：（1）色林错-普若岗日国家公园潜在建设区共鉴定出浮游植物127种,隶属于3门5纲11目18科35属,其中优势种5种,隶属2门5属,优势种丰度和优势度在不同区域均有差异;（2）泉生菱形藻（Nitzschia fonticola）生态位宽度最大,嗜盐舟形藻（Navicula halophila）生态位宽度最小;（3）浮游植物优势种生态位重叠程度不高,种间竞争弱,群落结构较为稳定;（4）浮游植物优势种呈发展或衰退趋势是不同浮游植物优势种间竞争的必然结果。本研究结果为色-普国家公园潜在建设区浮游植物多样性积累基础数据,为探讨生态位分化理论下的种间关系、资源利用及生态适应机制提供参考。     

内蒙古乌梁素海浮游植物优势种的生态位分析

为了摸清内蒙古乌梁素海浮游植物群落结构和物种间关系以及对环境资源的利用程度,2011年7月和2012年2月分别对乌梁素海浮游植物群落结构进行调查,在利用生态位理论的基础上,采用改进的Levins公式和Petraitis指数分析了内蒙古乌梁素海夏季和冬季优势种的生态位宽度和生态位重叠程度变化。结果显示,夏季湖中小空星藻(Coelastrum microporum)、栅藻(Scenedesmus mey)、小席藻(Phormidium tenu)和颤藻(Oscillatoria vauch)的生态位较宽,均大于3.6,而冬季的针杆藻(Synedra ehrenberg)和尾裸藻(Euglena caudata)的生态位较宽,均大于5.0。不同季节的生态位宽度显示,小空星藻、栅藻、小席藻和颤藻适合夏季生长环境,能充分利用湖泊周边环境资源;而针杆藻和尾裸藻在冬季更具有竞争能力。同物种在不同季节中的生态位重叠指数差异较大。生态响应速率分析结果表明,在夏季,除舟形藻(Navicula bory)的生长空间属衰退型外,其它优势种均处于发展状态,小席藻的发展空间最大,其次为螺旋藻(Spirulina princeps);在冬季,针杆藻、单鞭金藻(Monochrysis skuja)、卵形隐藻(Cryptomonas ovata)处于衰退状态,其它优势种均处于发展状态,小席藻的发展空间仍最大。浮游植物优势种典范对应排序结果表明,小席藻和螺旋藻受温度影响最大;硅藻门的舟形藻与水体中环境因子的相关性较低,针杆藻受水体p H值影响最大,大部分浮游植物种类的适盐性较低,丰度随盐度增加而减少。     

赤水河春季浮游植物群落结构变化及其优势种生态位分析

基于2011-2016年春季对赤水河4个断面浮游植物的调查,分析其群落结构变化及优势种生态位,揭示浮游植物群落变化规律、优势种的生态位分化及其环境适应性,可为赤水河浮游植物群落结构特征研究提供基础资料。结果显示,6年间在赤水河共采集到浮游植物7门、68属、233种（变种）,主要为硅藻,占比超过60%;浮游植物细胞密度在（17.28～136.68）×104个/L,各段面浮游植物密度年际间变化无显著差异,群落组成时间异质性较空间异质性明显,时空方差分解显示,时间变异可解释总变异的24.5%,空间变异仅解释总变异的2.0%;浮游植物多样性指数显示,2014年和2016年赤水河处于轻污或无污染状态,2011-2013年和2015年受到中度人为影响。2011-2016年春季赤水河共出现优势种31种（变种）,主要为广生态位和中生态位种,生态位重叠指数在同一门类物种中最高,在不同门类物种中最小。研究表明,赤水河春季浮游植物对水生态环境的适应能力强,对水环境变化有较好的适应性。     

金沙江下游浮游植物群落生态特征及与环境因子关系

为探究金沙江下游干流江段浮游植物群落特征及物种与生境之间的关系，于2019年6月和10月对金沙江下游攀枝花至水富段因梯级电站蓄水产生的三类不同水体（自然河流型、过渡型、类湖泊型）开展浮游植物与水环境调查，结果显示：2次调查共鉴定出浮游植物7门53属74种，主要以硅藻（47.30%）、绿藻（33.78%）和隐藻（6.76%）为主；浮游植物密度变化范围为13.9×104~105×104个/L，其中6月平均密度（54.92×104个/L）高于10月（27.22×104个/L），自然河流型水体平均密度低于其它两种类型水体。硅藻在自然河流型水体为绝对优势种，在过渡型水体和类湖泊型水体中其优势度降低，而蓝藻和绿藻优势度增加，但三种水体中以小环藻（Cyclotella sp.）平均优势度最大。各优势种6月生态位宽度Bi和生态位重叠ΔSOij分别为0.13~0.77和1.04~38.46，10月分别为0.10~0.80和3.55~39.48，和10月份相比，6月各优势种生态位宽度Bi较高，而优势种间生态位重叠ΔSOij数值较低，表明6月各优势种种间竞争态势相对均衡，群落状态相对稳定。Shannon-Wiener指数（H''）、Marglef指数（D）及Pielou均匀度指数（J）变化范围分别为1.99~2.69、2.56~5.88和0.50~0.78，总体表现为6月＞10月，自然河流型水体>过渡型水体>类湖泊型水体，各江段水体处于α-β中污染状态。浮游植物与环境因子的典范分析（Canonical Analysis）结果表明：透明度、流速、水温、溶解氧、总氮是影响浮游植物群落的主要环境因子，且不同优势种对环境因子的响应有所不同。研究可为金沙江下游梯级库区水资源保护和生态修复提供科学依据。     

石羊河尾闾青土湖荒漠植物群落种间关联及生态位研究

基于野外样地调查资料,采用方差比率法、χ_²检验、Pearson相关、Spearson秩相关、联结系数Ochiai和生态位量化方法,探究了荒漠植物群落种间关系,以期为石羊河尾闾干涸湖泊植被恢复与重建提供理论支撑。结果表明：青土湖荒漠植物群落包括24个植物种,其中灌木8种,多年生草本8种,一年生草本8种,草本植物占总物种数的66.67%。不同生活型荒漠植物中重要值最大的分别为白刺(Nitraria tangutorum)、芦苇(Phragmites australis)、猪毛菜(Salsola collina)。方差比率分析表明,青土湖荒漠植物群落种间总体上呈现不显著负联结的关系,群落处于波动演替状态。Ochiai系数0~0.3的种对占总对数的72.83%,种对间的相关性较弱。生态位宽度较大的灌木有白刺(21.728)、梭梭Haloxylon ammodendron(10.321)、黑果枸杞Lycium ruthenicum(5.711);多年生草本有芦苇(12.556)、黄花补血草Limonium aureum(4.874)、荒漠黄耆Astragalus grubovii(4.248);一年生草本猪毛菜(9.340)、盐生草(7.822)、虫实(2.330)。生态位重叠较大的种对有灰绿藜和碟果虫实(0.84)、沙蒿和戈壁驼蹄瓣(0.77)、黄花补血草和画眉草(0.77)、砂蓝刺头和红砂(0.75)。群落物种生态位重叠均值为0.12,种间竞争较小。建议在石羊河下游青土湖人工植物群落构建过程中重视种间关系,选择种间竞争小的灌木和多年生草本植物作为生态恢复的植物种。     

内蒙古典型湖泊秋季浮游植物群落特征及与环境变量的关系

2011年8月对内蒙古岱海、乌梁素海和呼伦湖等3个典型湖泊的浮游植物群落结构及水环境状况进行了调查。结果表明,3个湖泊都已达到富营养化水平,部分指标超过V类水标准,水环境状况不容乐观。呼伦湖和乌梁素海的浮游植物优势种为蓝藻且密度较高;因特殊的水环境条件,岱海的浮游植物优势种为绿藻中的卵囊藻。CCA分析结果表明,Cd和CODMn是影响秋季岱海浮游植物群落演替的重要因子;TP和BOD5是乌梁素海的重要因子;呼伦湖浮游植物群落结构受到影响的环境因子较多。     

贻贝养殖区大型底栖动物优势种生态位及种间联结性

为探究贻贝养殖区大型底栖动物群落结构的生态特征以及资源利用情况,基于2021年嵊泗枸杞岛贻贝养殖区春季(4月)和秋季(11月)的大型底栖动物调查数据,采用生态位宽度、生态位重叠、联结系数、冗余分析等方法探究了优势种时空生态位及种间联结关系。结果表明,研究区域共鉴定大型底栖动物132种,优势种共有13种,分别为不倒翁虫(Sternaspis scutate)、朝鲜阳遂足(Amphiura koreae)、刚鳃虫(Chaetozone setosa)等。生态位宽度范围为1.065～2.507,其中不倒翁虫生态位宽度最高。生态位重叠各种对间重叠值范围为0～0.83,其中重叠值最大的种对为刚鳃虫和细丝鳃虫(Cirratulus filiformis),梳鳃虫(Terebellides stroemii)与刚鳃虫、昆士兰稚齿虫(Prionospio queenslandica)、细丝鳃虫3组物种对以及异足索沙蚕(Kuwaita heteropoda)和中锐吻沙蚕(Glycera rouxii)种对生态位重叠值最小。方差比率法表明,大型底栖动物优势种总体呈现不显著负关联。卡方检验和联结系数也表明大...     

茂名市大放鸡岛海域浮游植物群落的季节变化

2003年8月、12月和2004年2月、5月在大放鸡岛海域多个站位进行了浮游生物调查,对该海区的浮游植物种类组成、不同季节各站位的细胞丰度分布、优势种及群落多样性进行了分析。四次调查共鉴定出浮游植物57种,大多数属浮游硅藻。角毛藻属、丹麦细柱藻、脆根管藻和尖刺菱形藻为全年优势种类。浮游植物细胞丰度大致为8月>12月>5月>2月。5月和8月浮游植物群落多样性水平较高,12月和2月浮游植物群落多样性水平较低。2月和5月群落均匀度较高,较为稳定,而8月和12月群落均匀度较低,稳定性差,少数种类因此大量繁殖,形成优势类群,成为赤潮暴发的潜在生物要素。     

Age,growth, maturity and the overfishing of the iconic sciaenid,Argyrosomus japonicus,in south-eastern,Australia

Mulloway (Argyrosomus japonicus) occur in estuarine and coastal waters surrounding Australia, Africa, India, Pakistan, China, Korea and Japan, where they are important in fisheries. This study identified that mulloway in south-eastern Australia had similar growth rates, but matured at smaller lengths and younger ages, to those in South Africa and Western Australia. Growth of both sexes was similar to about 5 years, after which females grew faster and attained a greater maximum length than males. Female mulloway matured at 4–5 years of age with a L₅₀ of 68 cm, whereas males matured at 2–3 years of age with a L₅₀ of 51 cm. The commercial fishery in New South Wales was characterised by declining catches and a reduction in the proportion of mulloway of mature lengths in landings. During 2002–2005 commercial landings were dominated (83%) by fish within 15 cm of the current minimum legal total length of 45 cm and aged 2 and 3 years (>80%), even though mulloway can attain lengths of 200 cm and live >30 years. Estimates of the rates of instantaneous total mortality ranged between 0.34 and 0.45, whilst the rate of instantaneous natural mortality (M) was estimated to be approximately 0.12. Yield-per-recruit analyses indicated that mulloway in New South Wales are being growth overfished and substantial increases in yield could be achieved by increasing the length at first harvest. Values of the spawning potential ratio were below 0.2 under a range of mortality estimates, suggesting that mulloway are at risk of recruitment overfishing. These results suggest that the spawning stock of mulloway in south-eastern Australia has been depleted and that remedial management action is required to protect this iconic species.     

Factors influencing the abundance of the common bully, Gobiomorphus cotidianus McDowall, in small, North Island, New Zealand, lakes

Adult common bullies, Gobiomorphus cotidianus McDowall, are small (total length =  30–120 mm), benthic fish commonly found in the littoral zones of New Zealand lakes where they are a major prey species for trout and eels. Differences in their relative abundance (CPUE) were determined between 21 shallow North Island lakes. Mean CPUE ranged from 2 to >  1000 fish net^{− 1} night^{− 1} and was inversely related to water transparency. The abundance of bullies was not reduced in lakes containing rainbow trout, Oncorhynchus mykiss (Walbaum), but was reduced in all lakes containing self-recruiting populations of eels, Anguilla spp. Mean densities of planktonic larval bullies in the limnetic zone were also inversely related to water transparency. Since low water transparency is related to increased trophic status for these lakes, the abundance of bullies is likely to be related to lake productivity, rather than turbidity.     

Nitrite Toxicity to the Razorback Sucker,Xyrauchen texanus,and the Bonytail,Gila elegans

ABSTRACT

Aquaculture for the purpose of supplementing natural recruitment is one approach used to assist the recovery of endangered fish populations. A common consequence of high-density culture is the accumulation of nitrite in the water. Razorback suckers (Catastomidae; Xyrauchen texanus) survived a 72-hour exposure to 25 mg/L nitrite-N. Bonytails (Cyprinidae; Gila elegans) died within 48 hours of exposure to 10 mg/L and 25 mg/L nitrite-N. A chloride:nitrite ratio of 5 (as either calcium chloride or sodium chloride) protected bonytail from nitrite toxicity. This study provides some basic knowledge that can be applied to the culture of these two endangered species and raises some interesting questions about the nature of nitrite toxicity and inhibition of toxicity in these two species.     

Interspecific competition between the round goby,Neogobius melanostomus,and the logperch,Percina caprodes,in the Duluth‐Superior Harbour

The Laurentian Great Lakes have been the site of numerous aquatic invasive species such as the sea lamprey, zebra mussel and round goby. To further understand interactions between invasive and native species in situ, competitive interactions between native logperch (Percina caprodes) and invasive round goby (Neogobius melanostomus) were examined using submerged enclosures in the Duluth‐Superior Harbour. Experiments were conducted on rocky or sandy substrate throughout the spring and summer months. Trials consisted of single fish, paired conspecifics or round goby/logperch pairs with weight change determined after 28 days. The round gobies were able to outcompete and/or negatively affect logperch on rocky substrates as a direct result of round goby/logperch interactions, as logperch fared well when round gobies were excluded from the enclosures. Although there is evidence that round gobies exclude logperch from rocky substrates, the logperch population remains close to pre‐invasion levels in the predominantly soft‐bottomed harbour. The continued coexistence of the logperch with the round goby is attributed to the vastly greater area of soft‐bottom vs. rocky substrate in the harbour, with the round gobies in the soft bottom younger and smaller than those in the rocky substrate. Recent evidence suggests that the round goby population is declining on the soft substrates indicating that the two populations will continue to coexist in the harbour.     

Optimizing the essential fatty acids, eicosapentaenoic and docosahexaenoic acid, in the diet of the prawn, Penaeus monodon

The dietary requirements of Penaeus monodon for eicosapentaenoic (20:5n‐3; EPA) and docosahexaenoic (22:6n‐3; DHA) acids were examined. These requirements were examined when dietary levels of linoleic (18:2n‐6; LOA) and linolenic acids (18:3n‐3; LNA) were also provided at previously established optimal levels of 14 and 21% respectively of the total lipid fatty acids. A 5 × 5 factorial design was used with incremental amounts (0, 4, 8, 12 and 16% of total fatty acids) of EPA and/or DHA. An additional diet containing cod‐liver oil was provided as a reference diet. The total lipid content of all of the 25 treatments and reference diets was maintained at the same level of 75 g kg^?1. Growth of prawns fed with the reference diet after 50 days was 244 ± 21%. The greatest response to singular additions of EPA or DHA was with a 12% inclusion of either fatty acid, resulting in 287 ± 21 and 293 ± 18% weight gain, respectively. Growth was generally better when combinations of EPA and DHA were used, the optimal combination being EPA 4% and DHA 4%, resulting in 335 ± 25% weight gain. Addition of high levels of either of the highly unsaturated fatty acids (HUFA) in the diet had a negative effect on growth. Digestibilities of the total neutral lipid and specific fatty acids were examined during the growth trials. The digestibility of total neutral lipid was usually higher when either or both HUFA were present, however there were few significant differences between treatments that contained either or both HUFA. Following the growth trials, digestive glands (DG) of prawns fed with the various diets were analysed to determine the total lipid content and fatty acid composition. Total lipid in the digestive gland increased with the inclusion of DHA, but was not significantly affected by the addition of EPA. The fatty acid composition of the digestive gland lipid generally reflected that of the diet. However, the maximum retention of EPA (11.1% of total DG fatty acids) and DHA (10.7% of total DG fatty acids), was not directly proportional to the amount of either fatty acid present in the diet. These results demonstrate that both EPA and DHA have considerable growth promoting capacity. This growth promoting capacity is enhanced when an optimal balance of both fatty acids are incorporated into the diet.     

Differences in the digestive biochemistry between the intertidal clam, Ruditapes decussatus, and the subtidal clam, Venerupis pullastra

The present study was aimed to evaluate differences in physicochemical characteristics (pH and temperature optima) of the main digestive enzymes (amylase, cellulase, laminarinase, and protease) in two commercially important bivalves, the intertidal clam, Ruditapes decussatus, and the subtidal clam, Venerupis pullastra, as well to assess individual variability of such activities. The assays were performed on extracts obtained from the digestive glands and crystalline styles of individuals collected in the wild and laboratory-conditioned during 1 week. In both species, maximum activity for amylase and cellulase was measured at pH 6 and that of laminarinase at pH 5.5, while pH profiles of protease activity showed important differences between them. Temperature profiles also showed interspecific variations, mainly in laminarinase. Carbohydrase activities were comparatively much higher in R. decussatus and proteolytic activities in V. pullastra. The observed differences both in physicochemical characteristics and relative importance of digestive enzymes are discussed in relation to the amount and type of food available in their respective habitats.     

Population structure,genetic diversity,and colonization history of the eastern pondmussel,Sagittunio nasutus,in the Great Lakes drainage

1. The eastern pondmussel, Sagittunio nasutus (Bivalvia: Unionida), has declined in abundance and distribution in eastern North America over the last few decades. The declines are predominantly the result of infestation by invasive dreissenid mussels and changes in habitat. The species is now considered imperilled across large portions of its distribution, especially in the Laurentian Great Lakes region.
2. The genetic diversity and structure of the remnant populations in the Great Lakes region were assessed using 10 newly developed microsatellite DNA loci for S. nasutus. Understanding the remaining populations can inform future management projects and determine whether the remnant populations have experienced a genetic bottleneck or a founder effect. We hope that this will inform the conservation of other species in regions founded by, and isolated from, a more genetically diverse source population or with disjointed geographical distributions.
3. Focusing on the Great Lakes region, samples (n = 428) from 62 collection sites in 28 water bodies were collected. Across the locations sampled for S. nasutus 11 genetic populations were identified, with significant genetic differentiation among them. The genetic structure of the species was assessed, with genetic similarities among populations compared and with geographical routes of colonization and gene flow evaluated.
4. Initial colonization from the Atlantic coast into Lake Erie and Lake Ontario is evident, followed by colonization events into nearby inland rivers and lakes. Analyses found evidence of inbreeding in all but one population and evidence of past genetic bottlenecks or strong founder effects in all but four populations. This study deepens our understanding of the genetic past and present of this imperilled species, providing conservation suggestions for the future management of the species.