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1.
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. 相似文献
2.
The invasion of Myriophyllum spicatum into Lake Nasser, and its impact on submerged macrophyte communities are quantitatively documented. Samples of macrophytes, water and hydrosoil were collected from 17 sites, in October and November 2002. The average dry weight standing crop of each species per grapnel haul was determined at each depth zone (sampling site). Twenty-one environmental variables were measured (12 water and 9 hydrosoil variables). Canonical correspondence analysis (CCA) was used to determine species–environment relationships. Comparing these relationships of the present study with those detected in 1988–1990 indicated significant changes in water and hydrosoil characteristics. These changes are also implicated in the submerged macrophyte communities. M. spicatum has replaced the originally dominant submerged macrophyte Najas marina subsp. armata. The study indicated that the invasion of M. spicatum depends not only on its attributes, but also on the physico-chemical characteristics of Lake Nasser. 相似文献
3.
The response of Ceratophyllum demersum and Myriophyllum spicatum to three levels of UV-B radiation – reduced (ca. 50% reduction), ambient and enhanced UV-B radiation, simulating 17% ozone depletion – is discussed. The research revealed
that UV-B stimulated the production of UV-B absorbing compounds in C. demersum, but not in M. spicatum. The relative amount of UV-B absorbing compounds was about four times lower in C. demersum. Enhanced UV-B also affected respiratory potential in C. demersum (on average 3.7 mg O2/gDM/h), but no effect on M. spicatum (on average 5.5 mg O2/gDM/h) was detected. Increased need for energy revealed that UV-B radiation exerted stress in C. demersum. No changes in chlorophyll a and no disturbance to photochemical efficiency due to UV-B were observed in either species. 相似文献
4.
Summary The effects of three species of fish (tilapia, grass carp and common carp) on the seeds of Najas marina L. and of Ruppia maritima L. were investigated. Practically all the seeds that were injested by the common carp were digested. The two other fish were less affective: they digested seeds with soft seed-coats but excreted a good portion of the hard ones. Germination of the excreted seeds was improved. Seeds have been retained in the digestion tracts of the fish for up to 65 h. It is thus suggested that tilapias and grass-carps play a role in the distribution and the improvement of reproduction of Najas and Ruppia. 相似文献
5.
为了解种间关系对沉水植物群落结构的影响,在不同光照(20%自然光和50%自然光)和不同物种组合下,研究了长江中下游常见优势沉水植物苦草(Vallisneria natans)与黑藻(Hydrilla verticillata)和穗状狐尾藻(Myriophyllum spicatum)的相互作用。结果表明,在低光下,苦草与穗状狐尾藻混种时,苦草生物量、株高和叶数均没有明显变化,当穗状狐尾藻的比例较高时,苦草根长生长受到抑制,根叶比呈下降趋势;在高光下,穗状狐尾藻比例的增加会促进苦草单株生物量和叶生物量的增加,而对苦草株高、根长和叶数无显著影响;与黑藻混种相比,苦草与穗状狐尾藻混种时,苦草的株高、根长和叶数均无显著差异,而苦草的单株生物量和叶生物量均呈降低趋势。因此,物种组合和混种比例均会影响苦草与其他物种的相互作用关系,进而影响沉水植被的群落动态。 相似文献
6.
The genetic variability of five natural populations ofNajas marina L., i.e. one diploid of subsp.marina (Europe), two of subsp.intermedia (Europe) and both a diploid (C. Africa) and a tetraploid (Middle East) of subsp.armata, has been estimated by means of electrophoretic studies. These populations differ in their morphology and karyotype. Emphasis is placed on the characteristics and status of a tetraploid cytotype from Merkaz Sappir (Israel). Almost all the variation observed is expressed in seed alcohol dehydrogenase (ADH). The differences are in a unique allele of theAdh-2 locus and in the formation of novel heteromeric isozymes.Adh genes in seeds can be used as a marker for the autotetraploid character. The other enzyme systems tested failed in this respect. The genetic variability based on 23 loci is rather low. Nevertheless, the autotetraploid population has a higher or equal ratio of polymorphic loci than the related diploids. Cluster analysis illustrated not only thatNajas marina subsp.marina has diverged much from subsp.intermedia and subsp.armata, but also showed the difference between the latter two taxa, as well as the intermediate position of the autotetraploid population. 相似文献
7.
Anti-cyanobacterial fatty acids released from <Emphasis Type="Italic">Myriophyllum spicatum</Emphasis> 总被引:1,自引:0,他引:1
This study was carried out to identify unknown allelochemicals released from Myriophyllum spicatum and to investigate their anti-cyanobacterial effects. A series of analyses of culture solutions and methanol extracts of M. spicatum using gas chromatograph equipped with a mass selective detector revealed that M. spicatum released fatty acids, specifically, nonanoic, tetradecanoic, hexadecanoic, octadecanoic, and octadecenoic acids. Nonanoic, cis-6-octadecenoic, and cis-9-octadecenoic acids significantly inhibited growth of Microcystis aeruginosa, whereas tetradecanoic, hexadecanoic, and octadecanoic acids did not show any effect. When the inhibitory effect of nonanoic acid was compared with those of 4 polyphenols and eugeniin, which are anti-cyanobacterial compounds previously reported to be released by M. spicatum, nonanoic acid was found to be the most inhibitory to M. aeruginosa. These results indicate that not only polyphenols and eugeniin but also fatty acids such as nonanoic acid must be studied to reveal how M. spicatum exerts its allelopathic effect on M. aeruginosa. 相似文献
8.
Exotic species can invade and establish new habitats both as a result of their own traits, and as a result of the characteristics
of the environment they invade. Here, we show that the abundance of the invasive submerged aquatic plant, Myriophyllum spicatum (Eurasian watermilfoil) is highly dependent on the conditions of the environment in a mesocosm experiment. M. spicatum is allelopathic towards epiphytic algae, and in the absence of algivorous snails, we found that the abundance of both algae
and M. spicatum significantly increased with experimentally increased nutrient loading, while the abundance of native submerged macrophytes
declined. However, when snails were present, snail biomass increased with increasing nutrient loading, and M. spicatum biomass was consistently low while native submerged macrophyte biomass was consistently high. Our results stress the importance
of the interaction between species traits and environmental conditions when considering the invasiveness of certain exotic
species and the invasibility of certain environments. 相似文献
9.
The trace metal (Fe, Mn, Zn, Cu, Ni, Pb, Cd, Sr, and Cr) contents in the most common submerged and floating aquatic plants Ceratophyllum demersum L., Myriophyllum spicatum L., and Nymphoides flava Hill. of Provala Lake were evaluated. Considerable higher contents of iron, manganese, zinc, nickel, lead and strontium were found in submerged species than in the floating ones. The presence of cadmium and lead in plant tissues points to a certain degree of lake water pollution. 相似文献
10.
The recent recognition of invasive hybrid watermilfoil (Myriophyllum
spicatum × M. sibiricum) in North America has necessitated a more thorough evaluation of its overall distribution and occurrence in natural populations.
A comprehensive survey of watermilfoil populations was conducted in five Minnesota lakes, three of which were suspected a
priori to contain hybrid watermilfoil. DNA sequence data verified that hybrid plants between the nonindigenous M. spicatum L. and indigenous M. sibiricum Kom. occurred in three of the five lakes sampled. Myriophyllum spicatum was not detected in lakes where hybrids were prevalent. Further sampling of lakes in Idaho, Michigan, Minnesota, Wisconsin
and Washington identified 30 additional hybrid watermilfoil populations. In only three of these populations the hybrid watermilfoil
was found to co-occur with M. spicatum. To facilitate the field identification of the two parental species and their hybrid, morphological data from watermilfoil
specimens collected across the United States were evaluated. We determined that leaf segment/leaf length measurements can
effectively distinguish M. spicatum and M. sibiricum; however, hybrids are intermediate for these characters and such measurements frequently overlap with respect to their parental
taxa. By incorporating a combined molecular and morphological approach to identifying watermilfoils, the hybrids can be identified
readily and their distributions elucidated both within and between lakes. Because hybrids may respond differently to local
ecological conditions than their parents, information on their presence and distribution should be of particular importance
to management and conservation programs. 相似文献
11.
Life history of Corophium curvispinum G. O. Sars (Crustacea,Amphipoda) living on macrophytes in Lake Balaton 总被引:2,自引:2,他引:0
Samples of the amphipod Corophium curvispinum were collected from Myriophyllum spicatum twice a month during the vegetation period. The animals were sexed, their length measured and the eggs of females were counted. Length frequency histograms served to follow the life history of C. curvispinum.Reproduction lasts from May to October. The animals born in May–June reproduce in the same year while the summer-autumn generation reproduces the following year. The life span is about 1 year. The highest fecundity was found in June, the lowest in October. 相似文献
12.
P. Chatenet D. Froissard J. Cook-Moreau P. Hourdin A. Ghestem M Botineau J. Haury 《Hydrobiologia》2006,570(1):61-65
Myriophyllum alterniflorum D.C. (Haloragaceae) was studied in the acidic to neutral rivers Vienne and Gartempe (Limousin region, France). Two complementary
levels of organisation were evaluated to determine their usefulness for pollution assessment: morphological traits of river
populations, and eco-physiological responses to ammonium enrichment in indoor experiments. Inter-node length, stem diameter
and leaf length were measured and their ratio calculated for 100 selected plants collected in 20 homogeneous areas. Using
multidimensional analysis, their ecological significance for trophic assessment was demonstrated: stem diameter was linked
to conductivity, and leaf length/stem diameter ratio to phosphates. Nitrate reductase activity was measured in three populations
(upstream, median and downstream populations) after experimental enrichment with ammonium. Ammonium enrichment decreased activity
starting at very low concentrations. However, inhibition levels depended on tested populations, with upstream populations
being less sensitive due to natural ammonium content in water. The differences could be explained by an eco-adaptation to
the trophic level of water. The relationships between the two levels of organisation are discussed. These results could help
to distinguish different ecotypes using Myriophyllum alterniflorum. 相似文献
13.
14.
Aquatic plants comprise few species worldwide, yet introductions of nonindigenous hydrophytes represent some of the most severe examples of biological invasions. Often innocuous in their indigenous regions, many aquatic plant species have caused extreme ecological and economic consequences when introduced into nonindigenous habitats. Typically, aquatic plant invasions are unnoticed or overlooked until they are perceived as problematic. By then, plants are virtually impossible to eradicate and negative ecological impacts caused by their spread into natural communities are irreparable. We present criteria to facilitate decisions whether a species should be characterized as nonindigenous or invasive. Historical data are used to clarify methods of introduction, avenues and means of dispersal, and extent of invasiveness of the following aquatic plants in southern New England: Acorus calamus, Butomus umbellatus, Cabomba caroliniana, Callitriche stagnalis, Egeria densa, Hydrilla verticillata, Limnobium spongia, Marsilea quadrifolia, Myriophyllum aquaticum, Myriophyllum heterophyllum, Myriophyllum spicatum, Najas minor, Najas guadalupensis, Nasturtium officinale, Nymphoides peltata, Potamogeton crispus, Trapa natans and Veronica beccabunga. 相似文献
15.
Epiphytic algae and macroinvertebrates on submerged and floating-leaved macrophytes in an Italian lake 总被引:1,自引:0,他引:1
Antonella Cattaneo Gaetano Galanti Silvia Gentinetta And Susana 《Freshwater Biology》1998,39(4):725-740
1. The presence of contiguous beds of submerged (Myriophyllum spicatum, Ceratophyllum demersum and Najas marina) and floating-leaved (Trapa natans) vegetation in a north Italian lake allowed us to test the effect of the different host architecture on epiphytic algae and invertebrates and to predict the consequences for the lake of changes in the predominant vegetation. 2. Epiphyton development, measured as carbon, nitrogen, phosphorus, chlorophyll a (Chl a), phaeophytin and as algal and macroinvertebrate density, was significantly higher on submerged plants than on T. natans. The C : Chl a ratio, a proxy of the ratio of heterotrophs to autotrophs, was higher on the floating-leaved plants. The elemental (C : N : P) and pigment (Chl a : phaeophytin) ratios were not significantly different between the two vegetation types. 3. The taxonomic composition of epiphytic algae and invertebrates was similar on the different plants. The more varied morphology of the floating-leaved T. natans resulted in a higher diversity of epiphytic algae, however, but not of macroinvertebrates. 4. There was a significant inverse relationship between epiphyton biomass and the standing crop of the host plant, suggesting a key role for light and water exchange in epiphyton development. 5. Replacement of floating-leaved by submerged plants would increase the total biomass of epiphytic algae and invertebrates. 相似文献
16.
Submerged vascular plants and water chemistry in the coastal marsh Albufera de Mallorca (Balearic Islands) 总被引:1,自引:0,他引:1
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. 相似文献
17.
The Effects of Competition on Growth and Biomass Allocation in Nymphoides peltata (Gmel.) O. Kuntze Growing in Microcosm 总被引:2,自引:1,他引:1
Two experiments were designed to investigate the effects of competition on growth and biomass allocation in Nymphoides peltata. First, competition between N. peltata and Zizania latifolia was assigned with the densities of N. peltata to Z. latifolia ratios of 4:0, 4:2, 4:4 and 4:8. The increase of density of Z. latifolia resulted in apparent decrease of total biomass, relative growth rate (RGR), leaf area ratio (LAR) and mean leaf area per plant of N. peltata. N. peltata allocated above-ground biomass to shoots and roots and decreased the ratios of above-ground to below-ground biomass (A
b/B
b) with increasing density of Z. latifolia. Second, competitions between N. peltata and emerged Z. latifolia, floating-leavedTrapa bispinosa and submerged Myriophyllum spicatum were studied in the mean time. Total biomass, A
b/B
b and mean leaf area per plant of N. peltata were higher when competing with floating-leaved T. bispinosa than in N. peltata growing in the community with submerged M. spicatum and emerged Z. latifolia. There were no significant differences in RGR, net assimilation rate (NAR) and LAR of N. peltata when growing with each of the competitor species. Our studies indicate that the growth of N. peltata is strongly inhibited by the presence of Z. latifolia, and N. peltata can show certain competitive advantages over T. bispinosa and M. spicatum. 相似文献
18.
Two experiments were conducted to investigate the effects of competition on growth and performance of Nymphoides peltata (Gmel.) O. Kuntze in microcosm. Part of the research on growth and biomass allocation of N. peltata in response to competition had been reported early (Wu, Z. & D. Yu, 2004, Hydrobiologia 527: 241–250). This paper focuses
on the morphological variations of N. peltata under competitive pressure. First, competition between N. peltata and Zizania latifolia (Griseb.) Turcz. ex Stapf. was assigned with the densities of N. peltata to Z. latifolia ratios of 4:0, 4:2, 4:4 and 4:8. Water surface coverage, surface area per leaf blade and number of leaves per plant of N. peltata all declined significantly with increasing density of competitor. Similar results were also found for petiole length and
density of branching. However, the variations of planting density did not significantly affect the number of ramets per plant
and the stolon length of N. peltata. Second, competitions between N. peltata and emerged Z. latifolia, floating-leaved Trapa bispinosa Roxb. and submerged Myriophyllum spicatum L. were also studied simultaneously. The results showed that significant difference was only found for the water surface
coverage of N. peltata. No other significant differences were found for the number of ramets per plant, number of leaves per plant, density of branching,
surface area per leaf blade, petiole length, and stolon length of N. peltata. Our studies indicate that N. peltata presents morphological variations when it is growing with Z. latifolia, such that the growth of above-ground parts decrease (i.e., leaf number, petiole length, branching density) and the growth
of below-ground parts remains stable (i.e., stolons length). However, N. peltata does not show apparent differences in morphology when it is growing with T. bispinosa or M. spicatum. Accordingly, we conclude that the growth of N. peltata may be apparently inhibited by the presence of Z. latifolia, while T. bispinosa and M. spicatum may have little impact on the growth and performance of N. peltata. 相似文献
19.
Decomposition of dominant submerged macrophytes: implications for nutrient release in Myall Lake, NSW, Australia 总被引:4,自引:0,他引:4
Daniel Shilla Takashi Asaeda Takeshi Fujino Brian Sanderson 《Wetlands Ecology and Management》2006,14(5):427-433
Breakdown and nutrient dynamics of submerged macrophytes were studied in Myall Lake, Australia. Mass loss of Myriophyllum sulsagineum was the lowest (64.90%) among the studied macrophytes during the 322 days followed by charophytes (60.79%), whereas Najas marina and Vallisneria gigantea lost 91.15 and 86.02% of their respective initial mass during that time. The overall exponential breakdown rates of Najas marina and Vallisneria gigantea were similar, with k-values of 0.24 and 0.23 day−1, respectively. These rates were significantly higher than the break down rates of charophytes (0.007 day−1) and M. sulsagineum (0.008 day−1). During growth phase, water column depicted lower nutrient concentrations while during decay period, significant increase
in water column nutrients resulted. Release of nutrients from decomposing macrophytes and incorporation of these nutrients
into sedimentary phase as well as uptake of nutrients by the growing macrophytes, can present a considerable cycling pathway
of nutrients in Myall lake system. The results of this study suggest that different submerged macrophytes may differ appreciably
in quality and may exhibit different decomposition rates, patterns and nutrient dynamics in aquatic ecosystems in general,
and Myall lakes in particular. 相似文献
20.
Possible allelopathic effects of substances released from the macrophytes Chara globularis, Elodea canadensis, Myriophyllum spicatum on the common green alga Scenedesmus obliquus were tested in the laboratory with plastic plants and untreated medium as controls. A two-phase approach was used in which
first the effects of physical presence of plants was studied (phase I) followed by the effects of plant culture filtrates
(phase II). In the presence of plastic plants growth was reduced only marginally, but strong growth inhibition of Scenedesmus occurred in the physical presence of all macrophytes. In contrast, filtrates from Chara had no growth inhibitory effect on Scenedesmus. Myriophyllum filtrate reduced particle-based growth rate by 7% compared to filtration controls, while Elodea culture filtrate reduced volume-based growth by 12%, chlorophyll-based growth by 28% and particle-based growth by 15%. Photosystem
II-efficiency of Scenedesmus was reduced in all three macrophyte treatments in phase I, but not in filtrates from macrophyte cultures (phase II). Thus,
while enzyme activity or other physiological aspects may have been affected, the current study yielded no proof for allelopathically
active compounds being directed at photosynthesis. Mean particle volume (MPV) of Scenedesmus was not influenced by macrophyte exudates and cultures remained dominated by unicells. The strong growth inhibitory effects
found for Scenedesmus in the physical presence of macrophytes, but not in plastic controls, and no or weaker response in nutrient-enriched filtrates,
suggest nutrient competition was a more powerful driving factor than allelochemicals. However, the experimental design does
not exclude disappearance of allelochemicals during the filtration process. 相似文献