Preference of Tilapia rendalli (Boulenger) for some species of aquatic plants

Preference of juvenile red-breasted bream, Tilapia rendalli (Boulenger), for the macrophytes Ceratophyllum demersum L., Lagarosiphon ilicifolius (Oberm), Najas pectinata (Magnus) and Valisneria aethiopica (Frenzl) was determined. Fish were offered a mixture of the four macrophytes in equal quantities to determine selection. Preference was shown for V. aethiopica , whilst C. demersum was least selected. This preference order was checked by examination of stomach contents of fish from the same population in the wild and the differences are discussed.     

黄河三角洲湿地水生植物组成及生态位

通过大范围的野外调查和室内测定,运用Levins及Pianka公式,对近代黄河三角洲湿地水生植物的构成及主要物种的生态位进行了研究.结果表明:调查样方内共有水生植物34 种,隶属于16科26属;各调查区域间物种组成和群落类型具有一定的差异性.区域形成的年份越久,其物种数和群落类型就越丰富;挺水植物中以芦苇的生态位宽度最大,为0.905,藨草的最低,为0.127; 沉水植物中轮藻、穗花狐尾藻、川蔓藻及小茨藻的生态位宽度较大,分别为0.783、0.673、0.669和0.640,金鱼藻的最低,仅为0.100.龙须眼子菜、大茨藻和苦草间,马来眼子菜和菹草间生态位重叠值较大,说明这几种植物具有相似的环境适应能力.物种的生态位宽度与该物种的分布范围及耐盐区间的大小存在显著的相关性,由此可以断定土壤和水体盐度是导致黄河三角洲湿地水生植物生态位分化的关键因子.     

Allelopathic activity of Ceratophyllum demersum L. and Najas marina ssp. intermedia (Wolfgang) Casper

Hydrobiologia - We investigated the allelopathic activity of two submersed macrophytes with different growth forms and nutrient uptake modes, Ceratophyllum demersum and Najas marina ssp....     

武汉东湖水生植物群落演替的研究

 本文根据1992～1993年调查结果并结合前人研究资料,讨论了东湖水生植物群落30多年来的动态变化及其与富营养化和渔业养殖等因素的关系,提出了东湖水生植物群落的演替系列是从微齿眼子菜阶段→微齿眼子菜+大茨藻+金鱼藻+狐尾藻阶段→微齿眼子菜消失阶段→大茨藻阶段→大茨藻+狐尾藻+苦草阶段。同时,还从物种生理生态、补偿和再生能力、生活史及生殖对策、种间关系等方面探讨了水生植物群落演替的物种替代机制及其演替模式,为湖泊水生植被恢复、人工调控和优化提供理论依据。     

破罡湖通江前后湖滨带夏季水生植物对比研究

对破罡湖通江前后相隔一年的湖滨带夏季水生植物种类组成及生物量进行的测量及对比研究表明：（1）通江一年并未造成该湖水生植物物种组成变化,该湖仍然延续了以往11属12种的种群格局,且挺水植物群落几乎不受影响;（2）通江引起了沉水植物群落优势种的变化,马来眼子菜、穗花狐尾藻和菹草出现较大幅度的衰退,玻璃藻赢得了竞争优势;（3）江湖对流打散了浮萍＋紫萍群落,金鱼藻生物量得以增加;（4）通江一年后,该湖平均生物量更为接近同类湖泊最佳保有生物量。     

Production of submerged aquatic plant communities of Doodhadhari lake Raipur, (M.P. India)

The biomass of submerged aquatic plant communities was studied periodically during two annual growth periods. Najas minor contributed 78% to the total standing biomass. Ceratophyllum demersum, Hydrilla, Nelumbo nucifera, Trapa bispinosa and Potamogeton crispus contributed towards the rest of the biomass. The production was 0.64 g./m.²/day for the growing seasons of one year.     

汉中地区汉水流域水生维管植物种类及地理分布

经野外调查,采集标本与鉴定分析,汉中地区汉水流域共有水生维管植物69种,包括蕨类植物3种,种子植物66种,分别隶属于32科48属。其中挺水植物41种,浮水及浮叶植物11种,沉水植物17种。66种种子植物分别隶属于46属,有7种地理分布类型,其中以世界分布类型成分居多,共21属,占本地区水生种子植物总属数的45．7％;热带分布类型成分13属,占28．3％,温带分布类型12属,占26．0％。调查分析发现8种6该区域的新分布种,即：竹叶眼子菜,南方眼子菜,小茨藻,大茨藻,水毛花,穗花狐尾藻,有梗石龙尾的狸藻;新记录属4个,即：茨藻属,狐尾藻属,石龙尾属和狸藻属;新记录科2个,即;茨藻科和小二仙草科。     

Inter-relationships between Najas marina L. and three other species of aquatic macrophytes

The ability of Najas marina L. to thrive in the presence of the submerged hydrophytes (Myriophyllum spicatum L. and Potamogeton lucens L.) and of an emerged hygrophyte (Scirpus litoralis Schard.) was investigated in Tel Aviv, Israel. Najas plants were unaffected by the presence of Potamogeton lucens and Scirpus litoralis, but were significantly suppressed by Myriophyllum. Bilateral negative relationships exist between Najas and Myriophyllum and these seem to be of an allelophatic nature, depending more on the nature of the accompanying species rather than on their mass.     

Feeding behaviour of yearling and older hybrid grass carp

Hybrid grass carp resulting from the cross of a female grass carp, Ctenopharyngodon idella (Val.), and a male bighead carp, Hypophthalmichthys ( Aristichthys ) nobilis Rich., 12–18 months old ( c . 300 mm T.L.) were studied in a two-part experiment to determine feeding preference and total daily consumption fish^-1 on selected species of aquatic plants. Fish were maintained in circular pools with 6840·8 1 of water inside a temperature-controlled greenhouse. Preference tests were conducted at three temperature ranges; 25–28° C, 17–20° C and 12–15° C. Based on the time to complete consumption or the relative quantity consumed, the most preferred plant was Lemna gibba when in combination with six other species. Chara sp., Najas guadalupensis and Potamogeton peciinatus were readily consumed and considered to be of about equal preference. Ceratophyllum demersum and Myriophyllum brasiliense were least preferred. Hybrid grass carp generally consumed as much plant material species^-1 and in the same order of preference at the 12–15°C range as they did at 25–28° C. In the second part, mean daily consumption (g) fish^-1 at 25·7–31·0° C for five plant species tested separately was as follows: Chara sp. 369·8; Lemna gibba 178·2; Najas guadalupensis 172·6; Hydrilla verticillata 106·4 and Ceratophyllum demersum 8·8.     

鄂东花马潮水生高等植物研究——Ⅱ.水生植被

花马湖位于湖北省鄂州市境内,面积约27.5km~2。湖中分布有水生高等植物82种2变种。花马湖水生植被可分为15个群丛,其中菱群丛、竹叶眼子菜群丛、金鱼藻+狐尾藻+菹草+苦草群丛较为重要。湖中水生植波呈不规则的环带状分布,并可划分为湿生、挺水、浮叶和沉水4个植被带,各带均有相应的群丛分布。     

Submerged vascular plants and water chemistry in the coastal marsh Albufera de Mallorca (Balearic Islands)

Ten species of aquatic macrophytes have been analyzed for seven environmental variables by means of a significance test. A synthetic view has been obtained through a cluster analysis for species and a principal component analysis for 17 variables which form the multidimensional space where we project the species habitats. Myriophyllum spicatum L., Najas marina L., Potamogeton crispus L., Potamogeton pectinatus L. and Zannichellia pedunculata Reichenb. are widely distributed in the Albufera. Ceratophyllum submersum L. and Ruppia maritima L. var. brevirostris Ag. are considered stenoic. The tolerance of Ceratophyllum submersum to salts is significantly low and that of Ruppia cirrhosa (Petagna) Grande and Ruppia maritima var. brevirostris significantly high. Ceratophyllum submersum has a significantly negative distribution with regard to chlorophyll a and phosphate concentrations. Ceratophyllum demersum L. and C. submersum primarily occur in nitrate-rich waters whereas Ruppia cirrhosa primarily occurs in low nitrate waters.     

Aquarium studies on the selectivity of 16 aquatic plants as food by fingerling hybrids of the cross between Ctenopharyngodon idella ♂ and Cyprinus carpio ♀

Fish hybrids of the cross Ctenopharyngodon idella ♂ (grass carp) and Cyprinus carpio ♀ (Israeli carp), averaging 124 mm total length and 20 g in weight were stocked in aquaria along with 16 different aquatic plants to determine which plants they would eat. Observations showed that one group of plants was highly utilized (Azolla caroliniana, Lemna spp., Cladophora sp., Spirogyra sp., Nymphaea odorata); another group was moderately utilized (Pistia stratiotes, Ruppia maritima, Najas flexilis, Limnobium spongia, Potamogeton pecti-natus). Two other groups were only poorly utilized (Ceratophyllum demersum, Eichhornia crassipes, Elodea sp.) , or not utilized (Cabomba caroliniana, Sigittaria sp., Myriophyllum pinnatum).     

浙江朱家尖观音湾古木层中果实与种子的分类学研究

报道了浙江舟山群岛朱家尖观音湾古木层中的种子植物的果实和种子 ,其中 1 4种已经被鉴定其属种 ,它们是南酸枣 ( Choerospondiasaxillaris)、椴树属 ( Tilia sp.)、樟 ( Cinnamomum camphora)、茄属 ( Solanumsp.)、忍冬属 ( Lonicera sp.)、山胡椒属 ( Lindera sp.)、苜蓿属 ( Medicago sp.)、荆三棱 ( Scirpusyagara)、金鱼藻属 ( Ceratophyllum sp.)、乌桕 ( Sapium sebif erum)、鹅耳枥属 ( Carpinus sp.)、野山楂 ( Crataegus cuneata)、浙江紫薇 ( Lagerstroemia chekiangensis)和朴树属 ( Celtis sp.)。根据地下古木层中的果实和种子的调查和分析 ,并参考了木材解剖和孢粉分析资料 ,我们认为这里的古木层历史植被类型曾经是亚热带常绿、落叶阔叶混交林植被     

Feeding behaviour of underyearling hybrids of the grass carp, Ctenopharyngodon idella♀ and the bighead, Hypophthalmicthys nobilis♂ on selected species of aquatic plants

Underyearling hybrids of the cross Ctenopharyngodon idella ♀ (grass carp) and Hypophthalmichthys nobilis ♂ (bighead), averaging 104.8 mm total length were stocked for two weeks in cement tanks holding 605 1 of water with various combinations of submersed or floating aquatic plants. The submersed species most preferred were Ceratophyllum demersum, Chara sp. and Najas guadalupensis. Hydrilla verticillata, Hygrophila polysperma, Myriophyllum pinnatum and Utricularia foliosa were fed on from a minor to moderate extent. No feeding damage was observed on Egeria densa and Potamogeton illinoensis. Azolla caroliniana, Lemna sp. and Wolffia columbiana were readily consumed while Salvinia rotundifolia was not preferred when in combination with these floating plant species. Feeding damage to the submersed roots of Eichhornia crassipes and Pistia stratiotes was minor during a 30 day period. Hybrid fingerlings readily fed on mosquito larvae and small leeches when offered to them in an aquarium on one occasion.     

Neuropeptide Y secretion from bovine chromaffin cells inhibits cyclic AMP accumulation

Neuropeptide Y (NPY) is secreted from bovine chromaffin cells in response to nicotinic receptor stimulation and may exhibit autocrine, paracrine or endocrine effects. Stimulation of bovine chromaffin cells with nicotine followed by the addition of forskolin (FSK) to the media results in a decrease in cyclic AMP accumulation compared to that seen in the absence of nicotine. Pertussis toxin (PTX) treatment or the addition of BIBP 3226, a selective NPY Y1 receptor antagonist prevents the inhibitory effect of nicotine. Fractionation of media obtained from cells stimulated with nicotine reveals an NPY-like substance that inhibits FSK-stimulated cAMP accumulation. Thus, an NPY-like substance can be secreted from bovine chromaffin cells in quantities sufficient to inhibit FSK-stimulated cAMP accumulation. These results suggest that NPY can act in an autocrine fashion to regulate chromaffin cell function.     

Photosynthesis in submersed macrophytes of a temperate lake

The photosynthetic carbon fixation pathways and levels of carbon-fixing enzymes of four dominant submersed macrophytes of Lawrence Lake, southern Michigan, were investigated during the main growth season (May to November). All four species (Scirpus subterminalis Torr., Najas flexilis (Willd.) Rostk. and Schmidt, Potamogeton praelongus Wulf., and Myriophyllum heterophyllum Michx.) were C₃ plants based on their patterns of ¹⁴C pulse-chase incorporation. High levels of phosphoenolpyruvate carboxylase were also found in these species. These levels, as well as the ribulose 1,5-biphosphate carboxylase/phosphoenolpyruvate carboxylase ratio of the leaves, varied throughout the growing season and exhibited highest values in July. No shift in carbon fixation pathways, however, could be detected from July to October. The possible functions of phosphoenolypyruvate carboxylase in these plants, as well as the significance of C₃ metabolism in submersed plants of temperate lakes, are delineated.     

Najas marina in Israel: It is a halophyte or a glycophyte?

In Israel Najas marina L. grows mainly in fresh water habitats. The halophytic nature of a population from one such habitat was investigated. NaCl had a positive effect on the growth of Najas , with an optimal concentration of 37–55 μ M . Germination percentage was only slightly reduced by NaCl up to a concentration of 74 μ M . It is thus concluded that the populations of Najas in Israel retain their halophytic nature. In fresh water habitats, Najas grows under suboptimal NaCl concentrations.     

Late Quaternary records of Najas spp. (Najadaceae) from the southwestern Baltic region

Seeds of the submerged vascular plants Najas marina, Najas minor and Najas flexilis are reported from submarine Holocene deposits from the southwestern part of the Baltic Sea, and we also report on a find of Najas minor from an Eemian deposit in Jutland, which is the first record of this species from the Eemian of Denmark. The common and widespread occurrence of especially the southern extralimital N. minor is indicative of higher than present summer temperatures during the period from 10300 to 8000cal.yearsBP.     

The position of Najas within the subclass Alismatidae (Monocotyledones) in the light of new evidence from seed coat structures in the Hydrocharitoideae (Hydrocharitales)

SHAFFER-FEHRE, M., 1991. The position of Najas within the Alismatidae (Monocotyledones) in the light of new evidence from seed coat structures in the Hydrocharitoideae (Hydrocharitaceae). This paper gives details of seed coat structure in several genera of the Hydrocharitoideae (Hydrocharitaceae) and of Najas (Najadaceae). The taxonomic position of Najas L., as a genus or as the basis of a higher taxonomic category, has changed with the publication of every new system of classification in which it was considered. In the light of evidence derived from seed coat anatomy, particularly that of the testa, and from the presence of endotegmen tuberculae, Najas is placed in the enlarged tribe Stratioteae in the subfamily Hydrocharitoideae (Hydrocharitaceae).     

Beiträge Zum Phytosoziologischen Studium Des Cernica-Sees

Zusammenfassung Das schwimmende Pleuston des Cernica Sees ist grösstenteils aus Pflanzen zusammengesetzt, die im Wasser oder auf dem Wasser schwimmen. Sie bilden folgende Assoziationen: Wolffietum arrhizae, Lemneto-Utricularietum, Ceratophylleto-Hydrocharetum, Ceratophylleto-Azolletum carolinianae, Lemneto-Azolletum filiculoidis, Lemneto-Spirodeletum, Lemnetum minoris, Lemnetum gibbae.Das Limnophyton umfasst die wurzelnden Pflanzen mit schwimmenden Organen:Nymphaea alba, Potamogeton natans oder Unterwasserpflanzen:Potamogeton crispus, P. pectinatus, P. lucens, Najas minor, Elodea canadensis, Myriophyllum spicatum, Ceratophyllum submersum usw. Gesellschaften des Limnophyton sind: Polygono-Potametum natantis, Elodeetum canadensis.Das Amphiphyton ist im Cernica See durchPolygonum amphibium natans, Sparganium ramosum vertreten. Von den Sumpfpflanzengesellschaften besonders wichtig ist das Scirpo-Phragmitetum. Einen besonderen Platz nehmen die schwimmenden Inseln ein, die als Phragmitetum natans auftreten.Von den 13 systematischen Einheiten die identifiziert werden konnten, sind noch zu erwähnen: Polygono-Potametum natantis, Elodeetum canadensis, Lemneto-Utricularietum ceratophylletosum demersi, Lemnetum minoris, Scirpeto-Phragmitetum typhosum laxmanni.Im Cernica See wurde eine neue Gesellschaft für die Wissenschaft beschrieben, Ceratophylleto-Azolletum carolinianae.An sumpfigen Stellen am Rande des Sees ist das Polygono-Bidentetum sehr verbreitet.