克隆整合和模拟沉积物淹埋对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)生长和抗氧化系统的影响

多数外来入侵水生植物都是克隆植物,而目前关于克隆整合属性对其入侵性潜在影响的研究仍旧缺乏.本文通过研究克隆整合(匍匐茎连接)和模拟沉积物淹埋(3 cm厚基质淹埋)对外来水生植物粉绿狐尾藻(Myriophyllum aquaticum)的生长、生物量分配和抗氧化酶活性的影响,探讨了克隆整合特性对粉绿狐尾藻耐受基质淹埋的作用机制.研究发现:基质淹埋显著降低了粉绿狐尾藻的生物量、总匍匐茎长度和分枝数,而克隆整合则显著促进了受淹埋分株的这些生长指标;基质淹埋显著降低了粉绿狐尾藻分株抗氧化酶(超氧化物歧化酶、过氧化物酶和过氧化氢酶)的活性,而克隆整合显著提升了受淹埋分株的抗氧化酶活性;此外,克隆整合显著降低了受淹埋分株的冠根比.以上结果表明:克隆整合效应能显著提升粉绿狐尾藻在基质淹埋胁迫下的活性氧清除能力,从而有助于其生长;能改变受胁迫分株生物量分配,提升其资源获取能力.因此,异质性环境胁迫下,粉绿狐尾藻的入侵性可能与其克隆整合属性密切相关.     

水深梯度对苦草(Vallisneria natans)克隆生长与觅食行为的影响

为了解水深梯度对苦草克隆生长与觅食行为的影响,通过大型原位浮台实验,将苦草幼苗盆栽后悬挂在不同水深(1.0、2.5、4.0、5.5、7.0 m)下培养,比较其生物量、无性系分株数、出芽数、株高、最大根长和匍匐茎总长的变化,并且评估了植株生物量对这些性状的影响.研究结果表明,随水深的增加苦草的生物量、无性系分株数、出芽数、最大根长、匍匐茎总长均显著降低,而株高随水深梯度呈先增加后降低的趋势.植株生物量仅对出芽数没有显著影响.水深梯度与植株生物量的交互作用仅对无性系分株数和匍匐茎总长有显著影响,而对其他性状没有显著影响,说明这两个性状对水深的响应受到个体发育的影响.     

不同水深条件下沉水植物苦草（Vallisneria natans）的形态响应和生长策略

苦草(Vallisneria natans)为我国常见的沉水植物之一,目前对水生态修复工程后苦草种群生长策略尚缺乏深入了解.以水生态修复工程1年后的苦草种群为研究对象,探讨水深对苦草叶片、匍匐茎、块茎等形态特征和苦草株数、匍匐茎数以及生物量等种群参数的影响,并分析水深胁迫下苦草的生长策略.结果表明,随着水深增加,尽管苦草单位面积株数和单位面积匍匐茎数均显著降低,但叶片长度、叶片宽度、叶片厚度、叶面积、匍匐茎长度、匍匐茎粗和块茎粗随水深显著增加,因而,苦草地上生物量也显著增加.其中,叶片长度和叶面积变异较大,对水深变化敏感,而叶片宽度、叶片厚度、匍匐茎长度、匍匐茎粗和块茎粗变异不大,对水深变化敏感程度低.在低光照胁迫下,苦草在亲株生长和子株输出之间存在权衡,一方面通过增加叶片投资保障亲株的资源利用效率,一方面通过降低亲株密度保障子株生长发育,从而实现种群空间生态位扩展和持续更新.在水生态修复工程中,考虑苦草的种群更新能力和施工的可操作性,在透明度为1.0~1.5m的条件下,苦草的适宜种植水深为0.5~1.0 m.     

环太湖地区河道和湖泊沿岸带水生植物多样性现状调查

环太湖地区经济发达,人口密集,近年来面临严重的富营养化、生境退化和外来水生物种入侵等环境问题.为明确环太湖地区河道和湖泊沿岸带水生植物多样性现状,于2018年开展本地和外来水生植物多样性调查.结果表明:(1)在环太湖地区共计进行65个群落样方调查分析,记录到38种水生植物,分属22科29属;(2)环太湖地区31个河道样方中入侵沉水植物水盾草重要值最高,其次为另一种入侵漂浮植物凤眼蓝,在34个湖泊沿岸带样方中凤眼蓝重要值最高;(3)环太湖地区河道和湖泊沿岸带样方生物多样性分别随着水盾草和凤眼蓝盖度的增加而降低,表明外来入侵植物影响水生植物生物多样性.环太湖地区湖泊需加强防范凤眼蓝漂浮生长分布范围扩大和水盾草沿河道入侵太湖湖区.这一地区同时面对水生植物覆盖面积减少和外来植物入侵问题,建议进行全太湖流域水生植物分布区域和生物多样性摸底普查,加强对外来入侵植物传播的监控,建立水生植物自然保护区.     

水位波动的幅度与频率对刺苦草(Vallisneria spinulosa)生物量和形态特征的影响

沉水植物是维持浅水湖泊清水稳态以及湖泊生态系统结构与功能的关键生物类群.近年来,气候变化和人类活动的双重作用造成湖泊水文情势的明显改变,对沉水植物的生长、繁殖和演替有着较大的影响.本文选取2个水位波动幅度与2个波动频率(逐渐改变水位),以恒定水位作为对照,研究湿地中具有重要生态功能的沉水植物刺苦草(Vallisneria spinulosa)的生物量及地上和地下营养器官形态结构对水位波动的响应.结果表明,相对于恒定水位,波动水位(低幅度低频率、低幅度高频率、高幅度低频率、高幅度高频率)对刺苦草的总生物量和获取限制资源相关器官有显著影响.相比于对照组,水位波动能够显著降低刺苦草分株数、叶片数、根数、根长、匍匐茎数、总匍匐茎长以及叶、根、地上和地下生物量,但会显著增加其株高和比叶面积.不同波动频率(低频率和高频率)和幅度(低幅度和高幅度)对光合器官的形态特征都没有显著影响,但叶和地上部分的生物量积累均受到波动幅度的显著影响.水位波动幅度显著改变了刺苦草的根数和根长,而波动频率的影响不显著.因此,对浅水湖泊受损刺苦草群落进行重建时,应避免较大幅度的水位波动,从而有利于增强植株快速恢复的能力.     

鄱阳湖国家级自然保护区的外来入侵植物调查

通过对鄱阳湖国家级自然保护区的实地调查,初步确定区内有外来入侵植物12科16属19种,其中菊科最多,有4种。研究表明:对鄱阳湖湿地危害较为严重的外来入侵种有裸柱菊、野胡萝卜、野老鹳草、空心莲子草等4种,外来植物入侵主要由人为活动无意引入和自然传入共同作用产生,在保护区内的分布受到湖泊水位影响。     

克氏原螯虾(Procambarus clarkii)对新鲜和不同分解腐烂程度的沉水植物摄食选择性研究

原产美国南部和墨西哥东北部的克氏原螯虾是目前全球入侵最广的小龙虾,也是对淡水生态系统最具破坏性的物种之一,其对栖息地沉水植物的现存量构成严重威胁,然而目前对克氏原螯虾摄食沉水植物的机制还知之甚少.本文选择6种沉水植物,研究克氏原螯虾对浅水湖泊常见的沉水植物穗花狐尾藻(Myriophyllum spicatum)、密刺苦草(Vallisneria denseserrulata)、轮叶黑藻(Hydrilla verticillata)、菹草(Potamogeton crispus L.)、马来眼子菜(Potamogeton malaianus)和金鱼藻(Ceratophyllum demersum)的新鲜植株和分解腐烂后的植株的摄食偏好及原因,结果表明克氏原螯虾对沉水植物新鲜植株选择逗留偏好为:最偏爱逗留在轮叶黑藻区,在穗花狐尾藻、密刺苦草和马来眼子菜3种植株区逗留频次无区别,而在金鱼藻区逗留频次显著最低,6种植物湿重减少量与逗留偏好趋势相似;相对各新鲜植株,克氏原螯虾均更喜欢逗留在分解腐烂8 d或12 d后的植物碎屑区域,相应分解腐烂8 d或12 d植物湿重降低量也显著更高.6种植物新鲜植株总酚类含量均显著高于分解腐烂后的植株,其中穗花狐尾藻新鲜和分解腐烂后的植株的总酚类含量始终显著高于其他5种植物.结合植物总酚类指标和摄食偏好结果,表明克氏原螯虾对沉水植物的摄食具有选择性,相对新鲜植物更喜摄食腐烂后的碎屑,总酚类不是影响其选择的关键因子.     

水深对沉水植物苦草(Vallisneria natans)和穗花狐尾藻(Myriophyllum spicatum)生长的影响

水深是影响浅水湖泊沉水植物生长的主要因素之一.莲座型苦草（Vallisneria natans）和冠层型穗花狐尾藻（Myriophyllum spicatum）是我国长江中下游浅水湖泊中常见的沉水植物种类，二者在形态特征上具有较大的差异.在自然水体中，水深变化对这两种植物的生长以及竞争格局的影响还有待研究.本文设计了3个水深梯度（水深0.5、1.5、2.5 m），探讨混栽条件下苦草和穗花狐尾藻生长和竞争格局对水深变化的响应.结果显示在实验系统内，中水深（1.5 m）处理组对两种植物的生长均最有利，表现为两种植物的相对生长率和生物量均最高.低水深（0.5 m）处理组苦草的生物量和相对生长率均显著低于高水深（2.5 m）处理组；穗花狐尾藻则相反，高水深对其生长的抑制作用更大.2种沉水植物在高水深胁迫时均表现出地上部分（叶长或茎长）增加，地下部分（根长）减少的形态响应特征.此外，随着水深由高到低，苦草与穗花狐尾藻生物量之比逐渐减小，表明苦草在两种植物中的竞争优势逐渐降低.研究表明湖泊水深变化不仅能够影响沉水植物的丰度，同时还可能会影响沉水植物的群落结构，而在我国浅水湖泊的生态修复实践中，在通过水位调控恢复沉水植物时，调控范围应考虑目标植物（如苦草）的光合特征.     

水深梯度对苦草(Vallisneria natans)光合荧光特性的影响

为研究水深梯度对苦草(Vallisneria natans)光合荧光特性的影响,实验设置0.6、1.3、2.0 m 3个水深条件,利用水下饱和脉冲荧光仪测定3种水深处理下苦草叶片的荧光参数和快速光响应曲线.结果表明:(1)随着水深增加,无性系分株数、叶片数、根系总长度、根系表面积等形态指标显著降低,而最大叶长、平均叶长、最大叶宽没有显著变化,2.0 m处苦草生长受到抑制;(2)不同水深对苦草叶片初始荧光F0和最大荧光Fm没有显著影响,而最大量子产率Fv/Fm和荧光参数Fv/F0随着水深增加显著增加,叶片光合系统Ⅱ光化学效率亦显著提高;(3)0.6 m处苦草的相对电子传递速率显著低于2.0 m处;(4)通过拟合光响应曲线所得的光响应曲线初始斜率、光抑制参数、最大电子传递速率以及半饱和光强在不同的水深处理间均差异显著;(5)2.0 m处苦草叶片的叶绿素a(Chl.a)、叶绿素b(Chl.b)、类胡萝卜素(Car)以及Chl.a+Chl.b含量均显著高于0.6 m处,而Chl.a/Chl.b和Car/Chl.a的差异则不显著.综上所述,0.6 m处苦草的光合能力较弱、保护机制强,而2.0 m则相反,从而说明苦草通过调节自身光合生理来适应不同水深环境.     

滇池水生植被演替及其与水环境变化关系

通过滇池水和植被和水体污染状况的全面高调查（１９９５－１９９７年）,揭示了水生植被的演替动态与环境质量变化的关系。结果表明,滇池现有水生植物２２种,以凤眼莲（Ｅｉｃｈｈｏｒｎｉａ ｃｒａｓｓｉｐｅｓ）、喜旱莲子草（ＡｌｔｅｒｎａｎｔｈｅａｒＰｈｉｌｏｘｅｒｏｉｄｅｓ）、龙须眼子菜（Ｐｏｔａｍｏｇｅｔｏｎ ｐｅｃｔｉｎａｔｕｓ）和取草（Ｍｙｒｉｏｐｈｙｌｌｕｍ ｓｐｉｃａｔｕｍ）等为优势种,其水生     

PBDEs in the blubber of marine mammals from coastal areas of São Paulo, Brazil, southwestern Atlantic

Limited information is available in the literature on the levels of brominated flame retardants in the southern hemisphere. This study presents concentrations of polybrominated diphenyl ethers (PBDEs) in the blubber of small cetaceans from the coast of São Paulo (Brazil), southwestern Atlantic. PBDE levels were highest in Stenellafrontalis (770 ng g⁻¹ lipid) followed by Stenobredanensis (475 ng g⁻¹ lipid), Sotaliaguianensis (65.6 ng g⁻¹ lipid), Tursiopstruncatus (64.2 ng g⁻¹ lipid) and Pontoporiablainvillei (60.3 ng g⁻¹ lipid). In general, continental shelf individuals exhibited higher contamination than inshore animals. This might be related to larger prey items consumed by continental shelf dolphins. The pattern of contamination indicates that Penta-BDE commercial mixtures are a major source of PBDEs to top predators in the southwestern Atlantic. Congeners found in Octa-BDE formulations were not detected in the investigated animals.     

Cloning and developmental expression of kinesin superfamily7 (kif7) in the brackish medaka (Oryzias melastigma), a close relative of the Japanese medaka (Oryzias latipes)

kif7 is a member of the kinesin superfamily members which are molecular motor proteins that move along microtubules in a highly regulated manner through ATP hydrolysis. In this paper, we report on the cloning of the Oryzias melastigma kif7 (omkif7) using primers designed according to the Japanese medaka (Oryzias latipes) database. The cloned omkif7 has an open reading frame of 3762bp and is deduced to encode a polypeptide of 1254 amino acids that possesses the putative ATP-binding and microtubule-binding motifs in its motor domain at the N-terminal region. We characterized the cloned omkif7 by comparison with the zebrafish kif7. Both omkif7 and zebrafish kif7 are shown to be expressed in all embryonic stages and adult tissues examined with higher expression level in the testis and ovary. Whole-mount in situ hybridization revealed that the expression of omkif7 is ubiquitous during the early stages of embryonic development, but became more restrictive and localized to the brain, fin bud and eye at later development. This study suggested that the brackish O.melastigma can serve as a good seawater model organism for developmental studies by utilizing the resources developed from its close relative of the Japanese medaka.     

Determination of the Geopotential Scale Factor from TOPEX/POSEIDON Satellite Altimetry

The geopotential scale factor R _o = GM/W _o (the GM geocentric gravitational constant adopted) and/or geoidal potential Wo have been determined on the basis of the first year's (Oct 92 – Dec 93) ERS-1/TOPEX/POSEIDON altimeter data and of the POCM 4B sea surface topography model: R _o °=(6 363 672.58°±0.05) m, W _o °=(62 636 855.8°±0.05)m ² s ^–2 . The 2°–°3 cm uncertainty in the altimeter calibration limits the actual accuracy of the solution. Monitoring dW _o /dt has been projected.     

外来种福寿螺(Pomacea canaliculata)对3种沉水植物的牧食偏好及水体理化因子的响应

外来种福寿螺(Pomacea canaliculata)相较我国本土螺类其牧食量更大且繁殖速度更快,对栖息地水生植物的现存量和实施水生植被恢复的生态治理工程的成功性可能构成威胁,目前对福寿螺影响浅水湖泊沉水植物的重建缺乏足够的研究.本文通过设置不同沉水植物种类组合系统,研究福寿螺对3种常用于浅水富营养化湖泊治理的沉水植物密刺苦草(Vallisneria denseserrulata)、轮叶黑藻(Hydrilla verticillata)、穗花狐尾藻(Myriophyllum spicatum)的牧食偏好以及不同植物配置系统理化因子的响应变化,结果表明福寿螺对沉水植物植株附着偏好为密刺苦草轮叶黑藻穗花狐尾藻,而牧食破坏强度为轮叶黑藻穗花狐尾藻密刺苦草,轮叶黑藻最容易受到福寿螺牧食影响而快速消亡,穗花狐尾藻叶片也会被全部牧食仅剩下茎,而苦草存活受到的影响较小.福寿螺会导致轮叶黑藻+密刺苦草组合系统中总氮、氨氮、总磷、正磷酸盐浓度显著升高,而密刺苦草+穗花狐尾藻组合中总磷、正磷酸盐浓度显著升高,但是在轮叶黑藻+穗花狐尾藻组合中仅总氮浓度显著升高.研究表明福寿螺能够影响沉水植物间的竞争关系,但是3种沉水植物均不能阻止福寿螺的牧食;福寿螺牧食会显著降低沉水植物生物量,最终会影响草型清水态系统的稳定性.     

Differential piscivory of the native Percichthys trucha and exotic salmonids upon the native forage fish Galaxias maculatus in Patagonian Andean lakes

The present paper analyses predation patterns, of Percichthys trucha and salmonid fish upon Galaxias maculatus in five lakes of northern Patagonia with differing community and environmental characteristics. Tank experiments were performed to evaluate relative efficiency of native and exotic predators of G. maculatus under treatments with and without cover (aquatic vegetation). Important differences were found between predators with regards to distribution and consumption of G. maculatus. Salmonids are more efficient than P. trucha in consuming G. maculatus in deep environments with scarcely vegetation; in contrast to native species they frequently use the pelagic environment. Although pelagic habitat might have served in the past as a refuge from native predators in the past, G maculatus now experiences intense predation in the pelagic zone by exotic salmonids. It is suggested that the widespread distribution of G. maculatus in Patagonian lakes may have facilitated the success of salmonids throughout Patagonia.     

Alien aquatic plants in a thermally abnormal river and their assembly to neophyte-dominated macrophyte stands (River Erft, Northrhine-Westphalia)

Floristic surveys, vegetation mapping, and detailed transect analyses rendered a macrophyte flora of 14 native and five alien taxa of flowering plants in the River Erft, a contributory of the River Rhine in Northrhine-Westphalia. Water temperatures of this river do not fall below 10 °C all the year round, for reasons of geothermically heated water discharged from nearby opencast mining areas. Macrophyte stand structures, composed of the neophytes Azolla filiculoides and Lemna minuta (floating) and Myriophyllum aquaticum, Egeria densa, and Vallisneria spiralis (rooted in the muddy or sandy ground of the river) are described and the ecological requirements of these taxa are characterized. The alien species can be seen as elements that increase the α-diversity of the aquatic vegetation of the River Erft. They do not replace any of the native species, even if shifts in the competition dynamics occur. The colonization by neophytes of the abnormally warmed River Erft can be appreciated as paradigmatic for trends in the macrophyte vegetation of medium-sized rivers in Central Europe when climate-related or discharge-based heating of the waterbody occurs and propagules of alien plants imported by waterfowl or – more important – plants from aquarium waste will find suitable places of existence and spread.     

Species differences in stomatal control of water loss at the canopy scale in a mature bottomland deciduous forest

In order to evaluate factors controlling transpiration of six common eastern deciduous species in North America, a model describing responses of canopy stomatal conductance (G_S) to net radiation (R_N), vapor pressure deficit (D) and relative extractable soil water (REW) was parameterized from sap flux data. Sap flux was measured in 24 mature trees consisting of the species Carya tomentosa, Quercus alba, Q. rubra, Fraxinus americana, Liriodendron tulipifera, and Liquidambar styraciflua in a bottomland oak-hickory forest in the Duke Forest, NC. Species differences in model coefficients were found during the 1997 growing season. All species showed a reduction in G_S with increasing D. R_N influenced G_S in the overstory shade intolerant L. styraciflua to a larger extent than the other species measured. In addition, despite a severe drought during the study period, only L. tulipifera showed a decline in G_S with decreasing REW. The primary effect of the drought for the other species appeared to be early autumn leaf senescence and abscission. As a result, despite the drought in this bottomland forest accustomed to ample water supply, maximum daily transpiration (1.6 mm) and growing season transpiration (264 mm) were similar to a nearby upland forest measured during a year of above average precipitation. These results may aid in assessing differences in water use and the ability of bottomland deciduous species to tolerate alterations in the frequency or amount of precipitation. Results also suggest little variation in water use among forests of similar composition and structure growing in different positions in the landscape and subjected to large interannual variation in water supply.     

近30 a云贵高原湖泊表面水体面积变化遥感监测与时空分析

以云贵高原湖泊近30 a来的TM、ETM~+和OLI遥感影像为数据源,采用归一化水体指数(NDWI)、改进归一化水体指数(MNDWI)、新型水体指数(NWI)、增强型水体指数(EWI)和自动水体提取指数5种水体指数提取了1985—2015年云贵高原10个湖泊表面水体面积,并对各种算法进行精度对比分析.针对湖泊各自特点采用不同的水体指数提取其表面水体面积,并进行水体面积变化时空分析.结果表明:云贵高原湖泊表面水体面积总体呈现先增加后缩减趋势,1985—1995年湖泊表面水体面积增加了30.86 km~2,1995—2015年湖泊水体表面面积减少了48.12 km~2,其中,面积变化最大的是杞麓湖与异龙湖.对云贵高原湖泊表面水体面积变化与该区域的年降水量、蒸发量、平均气温、流域植被覆盖面积和人类活动时空进行相关分析,结果表明:1)高原湖泊对区域气候变化的响应具有明显的空间差异性,云贵高原湖泊的表面水体面积与气候相关性较显著,气温升高引起蒸发加速,降水量下降,湖面不断缩小,与逐年上升的气温呈负相关,与逐年波动上升的蒸发量呈负相关,与逐年减少的降水量呈正相关;2)云贵高原湖泊各流域的植被覆盖面积与湖泊面积变化相关性较弱;3)人类活动是影响湖泊面积变化的重要因素,大肆围湖造田、围湖养殖以及旅游开发等人类活动直接导致云贵高原湖泊面积的锐减,并对湖泊生态环境产生重要影响.     

Fungal infection of Eudiaptomus gracilis (Copepoda, crustacea) in Lake Mondsee

An Aphanomyces sp. (Oomycetes) was found to be an important egg parasite of Eudiaptomus gracilis (Copepoda) in Lake Mondsee (Austria). The infection is evidenced by densely packed infection hyphae, attached with holdfasts and wrapped around the female's abdomen. The infection hyphae give rise to hyphae which penetrate the egg sac, and subsequently kill all eggs. The infection obviously has no pathogenetic effects on the egg-carrying female. Infected females appear during summer and fall, mainly in warm water layers. Infected egg clutches are found at all seasons of the year, indicating considerable birth control of the Eudiaptomus population by parasite infection. It seems possible that the actual Aphanomyces sp. is not the only parasite involved.     

1950s以来洪湖主要优势沉水植物群落变化

通过野外调查并结合历史数据对洪湖沉水植被进行长时间序列变化研究,构建自1950s以来洪湖主要优势沉水植物群落穗状狐尾藻(Myriophyllum spicatum)、微齿眼子菜(Potamogeton maackianus)、金鱼藻(Ceratophyllum demersum)和轮叶黑藻(Hydrilla verticillata)的群落分布图并计算其面积.结果表明:穗状狐尾藻群落面积从1950s占全湖的6%增加至1990s的65%,而后急剧下降至2010年的2%,然后又恢复至2014年的15%;微齿眼子菜群落面积从1950s的10%增至1990s的65%,然后下降至2014年的38%;金鱼藻群落面积从1980s的6%增至1990s的39%,2010年以后则稳定在25%;轮叶黑藻群落面积1950s占全湖的32%,随后急剧下降至1980s的6%,2000年以后逐步增加,至2014年为15%.1950s1990s,穗状狐尾藻、微齿眼子菜和金鱼藻群落分布范围从周边向湖心扩展,而轮叶黑藻群落从湖中心消失;2000年以后洪湖沉水植物群落分布破碎化明显.分析认为,1950s 1990s的围垦和水文过程变化,1990s 2005年的围网养殖、水生植物过度利用以及由此导致的水质恶化等,以及2006年至今开展的拆围和生态修复是导致这些变化的主要因素.建议取缔围网,控制入湖水质,提高水体透明度,促进水生植被恢复,但同时增加水位变幅,促进植物资源合理利用,避免沼泽化重演.