Submerged Macrophytes Ceratophyllum Demersum Research Articles

Ceratophyllum demersum the submerged macrophyte from the mining subsidence reservoir Nadrybie Poland as a source of anticancer agents

Aquatic plants are a rich source of health-beneficial substances. One of such organisms is the submerged macrophyte Ceratophyllum demersum, which has not been sufficiently studied in this aspect so far. In this work, we have studied environmental conditions prevailing in a subsidence mining reservoir in Eastern Poland and shown that C. demersum can be harvested for further analysis even from artificial anthropogenic reservoirs. The phytochemical analysis of C. demersum ethanolic extract using LC–MS revealed high content of phenolic compounds (18.50 mg/g) (mainly flavonoids, 16.09 mg/g), including those that have not yet been identified in this plant, namely isorhamnetin, sakuranetin, taxifolin, and eriodictyol. Such rich flavonoid content is most likely responsible for the anticancer activity of the C. demersum extract, which was targeted especially at neoplastic cells of gastrointestinal tract origin. The flow cytometry analysis of treated cells showed an increased percentage of late apoptotic and necrotic cells. The fish embryo toxicity (FET) test showed safety of the extract towards Danio rerio fish up to the concentration of 225 µg/ml. This study has shown that the submerged macrophyte Ceratophyllum demersum can be taken into consideration as a rich source of a set of anticancer agents with chemopreventive potential.

Genetic diversity of the submerged macrophyte Ceratophyllum demersum depends on habitat hydrology and habitat fragmentation.

The adaptability of plant populations to a changing environment depends on their genetic diversity, which in turn is influenced by the degree of sexual reproduction and gene flow from distant areas. Aquatic macrophytes can reproduce both sexually and asexually, and their reproductive fragments are spread in various ways (e.g. by water). Although these plants are obviously exposed to hydrological changes, the degree of vulnerability may depend on the types of their reproduction and distribution, as well as the hydrological differences of habitats. The aim of this study was to investigate the genetic diversity of the cosmopolitan macrophyte Ceratophyllum demersum in hydrologically different aquatic habitats, i.e. rivers and backwaters separated from the main river bed to a different extent. For this purpose, the first microsatellite primer set was developed for this species. Using 10 developed primer pairs, a high level of genetic variation was explored in C. demersum populations. Overall, more than 80% of the loci were found to be polymorphic, a total of 46 different multilocus genotypes and 18 private alleles were detected in the 63 individuals examined. The results demonstrated that microsatellite polymorphism in this species depends on habitat hydrology. The greatest genetic variability was revealed in populations of rivers, where flowing water provides constant longitudinal connections with distant habitats. The populations of the hydrologically isolated backwaters showed the lowest microsatellite polymorphism, while plants from an oxbow occasionally flooded by the main river had medium genetic diversity. The results highlight that in contrast to species that spread independently of water flow or among hydrologically isolated water bodies, macrophytes with exclusive or dominant hydrochory may be most severely affected by habitat fragmentation, for example due to climate change.

Testing the effect of the submerged macrophyte Ceratophyllum demersum (L.) on heterotrophic bacterioplankton densities under different levels of nitrogen and phosphorus concentrations in shallow lake mesocosms

To investigate the effect of submerged macrophytes on heterotrophic bacterioplankton communities in response to nutrient enrichment, we simulated mesocosms to test two factors, namely, the presence of Ceratophyllum demersum (L.) and the level of nutrients (slight and medium nutrient enrichment) under four possible system combinations for a duration of more than 3 months. The results show that C. demersum can affect the temporal dynamics of heterotrophic bacterioplankton density (HBD) and cause it to decrease. However, the effect of C. demersum on HBD was more pronounced under medium nutrient enrichment. The mean values of HBD in the treatment and control systems under slight nutrient enrichment were 1.30 × 105 cells mL−1 and 1.34 × 105 cells mL−1, respectively; whereas for medium nutrient enrichment, they were 1.78 × 105 cells mL−1 and 2.65 × 105 cells mL−1, respectively. The total nitrogen (TN) and total phosphorus (TP) concentrations were maintained throughout the experiment, and no significant differences were observed in the pH value, chlorophyll a (Chl. a) concentrations or dissolved organic carbon (DOC) levels between the systems with and without macrophytes, regardless of the nutrient level. Furthermore, linear mixed models revealed that environmental variables had a limited impact on HBD and that C. demersum had no significant direct effect on the environmental variables in the systems. A likely explanation is higher predation on bacterioplankton in the mesocosms, although allelopathic effects exerted by C. demersum cannot be excluded.

Responses of submerged macrophyte Ceratophyllum demersum to the gradient concentrations of microcystin-LR (MC-LR).

The responses of Ceratophyllum demersum to gradient concentrations (0, 0.8, 3.2, and 10µg/L) of microcystin-LR (MC-LR) were comprehensively investigated by laboratory simulation experiments. The high reduction and accumulation efficiency of MC-LR by C. demersum were verified in this study. Results showed that the reduction ratio of MC-LR in the cultivation medium was up to 99% after 14days of exposure, and the accumulation of MC-LR in C. demersum was highest at an exposure concentration of 10μg/L, the value of which was 0.9ng/g fresh weight (FW). Meanwhile, a series of negative effects on C. demersum was detectable, accompanied by a significant biomass reduction of the plant and changes in microbial community composition. In particular, this study indicated that the amount of Flavobacteria was elevated under the stress of MC-LR, provoking great threats to aquatic ecosystems. Moreover, oxidative damage was evidenced by the changes in total antioxidant capacity, superoxide dismutase, and glutathione. The results also demonstrated significant increases in sugar (0.025mg/g FW), protein (0.3mg/g FW), and carotenoids (0.6mg/g FW) in C. demersum stressed by 10μg/L of MC-LR, compared with the control without microcystins, which were among the defense strategies for dealing with adverse conditions. These results verified the good potential of submerged macrophytes as an eco-friendly strategy for controlling cyanobacterial blooms. However, the negative effects of MC-LR on the macrophytes themselves were also demonstrated, which would be considered in future practice and management.

Isolated and combined effects of a submerged macrophyte and a cladoceran on the interactions between Microcystis aeruginosa (Cyanobacteria) and Raphidocelis subcapitata (Chlorophyta)

Introduction: Cyanobacterial blooms in tropical water bodies are increasingly common, because of eutrophication and rising temperatures. Consequently, many freshwater systems are affected, by reducing water quality, biodiversity, and ecosystem services. With the increased frequency of harmful algal blooms, the development of biological tools to improve water quality is an urgent issue. Objective: To evaluate the effects of a submerged macrophyte and a cladoceran on the microcystin-producing cyanobacteria Microcystis aeruginosa (NPLJ-4) and the chlorophyte Raphidocelis subcapitata (BMIUFRPE-02) in mixed cultures. Methods: Two parallel experiments were carried out for ten days to evaluate the effects of the submerged macrophyte Ceratophyllum demersum and the cladoceran Moina micrura on microalgal interactions. Microalgal strains were cultivated in the ASM1 culture medium, under controlled laboratory conditions. The first experiment presented four treatments: M (C. demersum), Z (M. micrura), MZ (C. demersum and M. micrura), and C (control). Meanwhile, the second experiment consisted of five treatments, in which the microalgae were cultivated together at different Microcystis:Raphidocelis ratios: 1:0, 3:1, 1:1, 1:3, and 0:1. Biomass and growth rates of the strains were evaluated every two days, which were statistically treated with three-way or two-way repeated-measures ANOVA. Results: In the first experiment, M. aeruginosa was significantly inhibited in M and MZ treatments from the second day, and Z from the fourth, while R. subcapitata showed no reduction in its biomass in any treatment. On the other hand, R. subcapitata was stimulated from the eighth and tenth days in M treatment and only on the eighth day in Z treatment. In the second experiment, M. aeruginosa was significantly inhibited when cultivated with R. subcapitata in low ratios (Microcystis:Raphidocelis ratio of 1:3) throughout the experiment, while the chlorophyte was stimulated in that treatment. Conclusions: The coexistence of a cyanobacterium with a green alga did not alter the main negative response of M. aeruginosa to the submerged macrophyte and zooplankton but stimulated the green alga. Accordingly, the introduction of submerged macrophytes and cladocerans already adapted to eutrophic conditions, both isolated and combined, proved to be a good method to control cyanobacterial blooms without negatively affecting other coexisting phytoplankton species.

Effects of ammonium levels on growth and accumulation of antioxidative flavones of the submerged macrophyte Ceratophyllum demersum

Field data on the occurrence of the common and cosmopolitan submerged macrophyte Ceratophyllum demersum in relation to the water ammonium content were compared with the response of the plants to different ammonium treatments performed in the laboratory. Ammonium concentrations above 10 μM in the monitored area were found to be a strong limiting factor on the presence of C. demersum in water bodies. On the other hand, no adverse effect of nitrate was observed. In short-term laboratory experiments, the plants grew well even at 100 μM ammonium at pH 7.5, but higher concentrations affected the plant. Laboratory experiments showed that the accumulation of flavonoids with antioxidant properties was induced by ammonium. The detailed LC/MS analysis of the major flavonoids showed that the most abundant compound was tricetin present mainly as a monoglycoside in crude extracts. Luteolin, selgin, apigenin, tricin and chrysoeriol glycosides were also present in considerable amounts. Tricetin, a flavonoid having strong antioxidative properties, was most induced by higher ammonium levels. At high ammonium concentrations, plant tissues exhibited notable damage and the production of antioxidants declined.

Allelopathic effects of the aquatic macrophyte Ceratophyllum demersum L. on phytoplankton species: contrasting effects between cyanobacteria and chlorophytes

Abstract Aim To assess the allelopathic effects of the submerged macrophyte Ceratophyllum demersum on four strains of phytoplankton species: two cyanobacteria (Microcystis aeruginosa - microcystin producing and M. panniformis - non-microcystin producing), and two chlorophytes (Ankistrodesmus falcatus and Raphidocelis subcapitata). Methods A coexistence experiment between C. demersum and the four strains was carried out for six days, with eight treatments and three replicates. The strains were cultivated in ASM1 culture medium, under controlled laboratory conditions. Two treatments were assigned for each strain, one with 6 g.L-1 of the macrophyte, and the control without the plant. Biomasses and growth rates of the strains were evaluated every two days, which were compared through the T-test and two-way ANOVA, respectively. Results The results varied among the strains, with toxic M. aeruginosa being intensely inhibited by C. demersum, with a decrease of 99.5% in its biomass (p<0.001), while non-toxic M. panniformis was less affected by the allelochemicals, with a reduction of 86.2% (p<0.001). Ankistrodesmus falcatus delayed its growth when in coexistence with the macrophyte, decreasing its biomass in 50.4% (p<0.01), while R. subcapitata was not altered (p>0.05). In coexistence with C. demersum, M. aeruginosa exhibited the lowest growth rates (-0.65 d-1), followed by M. panniformis (-0.15 d-1), A. falcatus (0.19 d-1), and R. subcapitata (0.34 d-1), with significant differences between all strains (p<0.001). Microcystis aeruginosa presented higher inhibition rates than M. panniformis (p<0.001), as well as, A. falcatus was more inhibited than R. subcapitata (p<0.05). Conclusions The presence of microcystins could influence the allelopathic responses of C. demersum, that may release more allelochemicals in coexistence with toxic strains of M. aeruginosa. Accordingly, C. demersum can be used in biomanipulation strategies to control toxic and non-toxic cyanobacterial blooms, without damaging other phytoplankton species, like chlorophytes.

Combined effects of phosphate-solubilizing bacterium XMT-5 (Rhizobium sp.) and submerged macrophyte Ceratophyllum demersum on phosphorus release in eutrophic lake sediments.

Simulation experiments were conducted using sediments collected from the Taihu Lake to determine the combined effects of submerged macrophytes Ceratophyllum demersum and phosphate-solubilizing bacteria (PSB) strain XMT-5 (Rhizobium sp.) on phosphorus (P) concentrations in overlying waters and sediments. After 30days of experimental incubation, the total phosphorus (TP) and dissolved total phosphorus (DTP) concentrations of the overlying water subjected to AMB and AHMB treatments (both with the combined effects of PSB cells and submerged macrophytes) were generally lower than those of the AM (with individual effects of inoculated C. demersum) and AB (with individual effects of a smaller amount of inoculated PSB cells) control treatments but higher than that of the A (with no effects of inoculated PSB cells or C. demersum) and AHB (with individual effects of a larger amount of inoculated PSB) control treatments. The TP contents of the sediment in the AMB and AHMB treatments were significantly lower than those of the other control treatments. The TP contents of the C. demersum cocultured with the PSB strain XMT-5 cells in the AMB and AHMB treatments were all significantly higher than that of the AM treatment, indicating the enhancement of P uptake by submerged plants inoculated with PSB. The bacterial diversity structures of the rhizosphere sediment subjected to different treatments were also analyzed by the high-throughput sequencing method. According to the ACE and Chao 1 indices, the bacterial diversity in the AMB and AHMB treatments were the highest. Although many sources contributed to the decrease in the nutrient loads of the lake sediment, harvesting macrophytes inoculated with PSB cells prior to their senescence might constitute a significant in-lake measure for reducing internal P load.

Effects of water regime on the growth of the submerged macrophyte Ceratophyllum demersum at different densities

ABSTRACTTo successfully restore deteriorated lake ecosystems, it is vital to identify influencing environmental factors that impact submerged macrophytes. Planting density and water regime are important factors for submerged macrophytes’ growth. While many experimental studies have examined effects of water regime on the growth of some aquatic plant species, very few have tested both planting density and water regime on population, individual, and internode growth of a submerged population. We constructed Ceratophyllum demersum populations at two density levels (four and 16 shoot fragments per pot, responding to 96 and 384 plants m−2), subjected to two static water depths (30 and 150 cm) and to low, medium, and high water level fluctuation frequencies (24, 12, and 6 days per fluctuation cycle of water depth change between 30 and 150 cm). Initial density had no significant effect on individuals of C. demersum; however, it had a positive effect on population performance. Fluctuation frequency did not affect the growth of C. demersum, whereas increasing water depth significantly decreased both individual and internode biomass, and also increased shoot length regardless of comparison level. We therefore conclude that managing water depth and establishing populations with higher plant density may be helpful for the restoration of submerged macrophytes in degraded wetlands.

Effectiveness of Diquat, Copper Hydroxide, Copper Oxychloride and their Association in Control of Submerged Macrophytes Ceratophyllum demersum

The aims of this study were to evaluate the effectiveness of diquat, copper hydroxide, copper oxychloride and their associations diquat + 0.1% copper oxychloride and diquat + 0.1% copper hydroxide to control Cerathophyllum demersum. Therefore, the concentrations used were 0.1, 0.3, 0.5, 0.7, 1.0 and 1.5 mg L-1 oxychloride and copper hydroxide and 0.2, 0.4, 0.8 and 1.2 mg L-1 diquat and their associations with 0.1% copper oxychloride and 0.1% copper and a control hydroxide. The experimental design was completely randomized with ten replications for 45 days. For evaluation we used a scale of 0-100% control of notes and rated the weight (g) and length (cm) of pointers at the end of the trial period. Diquat showed 100% efficacy at 30 DAA, associations in 21 DAA and copper sources promoted regrowth of C. demersum. Diquat and its associations were more effective in controlling C. demersum. The use of herbicide in combination with a copper source is more efficient for the control of submerged weeds because it potentiates the effect of the herbicide in weed control

Influences of a submerged macrophyte on colony formation and growth of a green alga

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 19:265-274 (2013) - DOI: https://doi.org/10.3354/ab00533 Influences of a submerged macrophyte on colony formation and growth of a green alga J. Dong1,2, J. J. Lu1,2, G. B. Li1,*, L. R. Song1 1State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China 2University of Chinese Academy of Sciences, Beijing 100039, PR China *Corresponding author. Email: ligb@ihb.ac.cn ABSTRACT: The effects of the submerged macrophyte Ceratophyllum demersum on the growth and morphology of the green alga Scenedesmus obliquus were assessed by conducting co-culture laboratory experiments (15 and 25°C, presence/absence of 3 g fresh wt of C. demersum per litre of water in S. obliquus culture). Growth rate, photosynthetic pigment-based growth, photosynthetic activity and colony formation of S. obliquus increased in the presence of C. demersum. The proportion of 4-celled colonies of S. obliquus increased from 36 to 76% at 25°C, and from 51 to 71% at 15°C in the presence of C. demersum. The induced morphological shift from unicells to colonies in S. obliquus promoted sedimentation to the bottom-water region, thereby providing a competitive advantage for the submerged macrophyte. KEY WORDS: Scenedesmus obliquus · Ceratophyllum demersum · Growth · Colony formation · Sedimentation Full text in pdf format PreviousNextCite this article as: Dong J, Lu JJ, Li GB, Song LR (2013) Influences of a submerged macrophyte on colony formation and growth of a green alga. Aquat Biol 19:265-274. https://doi.org/10.3354/ab00533 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 19, No. 3. Online publication date: November 11, 2013 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2013 Inter-Research.

Time-dependent alterations in growth, photosynthetic pigments and enzymatic defense systems of submerged Ceratophyllum demersum during exposure to the cyanobacterial neurotoxin anatoxin-a

Recently, aquatic macrophytes have been considered as promising tools for eco-friendly water management with a low running cost. However, only little information is available thus far regarding the metabolic capacity of macrophytes for coping with cyanobacterial toxins (cyanotoxins) in the aquatic environment. Cyanotoxins have become emerging contaminants of great concern due to the high proliferation of cyanobacteria (cyanobacterial bloom) accelerated by eutrophication and climate change. Anatoxin-a, one of the common and major cyanotoxins, is suggested as a high priority water pollutant for regulatory consideration owing to its notoriously rapid mode of action as a neurotoxin. In this study, the time-course metabolic regulation of the submerged macrophyte Ceratophyllum demersum (C. demersum) was investigated during exposure to anatoxin-a at an environmentally relevant concentration (15μg/L). Biotransformation and antioxidative systems in C. demersum responded positively to anatoxin-a through the promoted synthesis of most of the involved enzymes within 8h. Maximum enzyme activities were exhibited after 24 or 48h of exposure to anatoxin-a. However, an apparent decline in enzyme activities was also observed at longer exposure duration (168 and 336h) in company with high steady-state levels of cell internal H2O2, which showed its highest level after 48h. Meanwhile, irreversible inhibitory influence on chlorophyll content (vitality) was noticed, whereas the ratio of carotenoids to total chlorophyll was increased with the increase in exposure duration. Consequently, the reduction in growth (biomass) of C. demersum was observed in sub-chronic exposure to anatoxin-a (8 weeks). Overall results clearly indicate, on the one hand, that anatoxin-a causes negative allelopathic effects on the macrophyte by inducing oxidative stress. On the other hand, the macrophyte might have interactions with anatoxin-a, based on the prompt reaction of its enzymatic defense systems to the toxin. The result obtained from the present study could contribute to the improvement of basic knowledge about the ecological impact of anatoxin-a and the environmental fate of the toxin in the aquatic environment.

Phytotoxic effects of the cyanobacterial neurotoxin anatoxin-a: Morphological, physiological and biochemical responses in aquatic macrophyte, Ceratophyllum demersum

Anatoxin-a is one of the common and major cyanobacterial neurotoxins acting as a powerful agonist at nicotinic acetylcholine receptors (nAChR). In recent years, the toxin has become the focus of public attention, due to the mass development of cyanobacteria (cyanobacterial blooms) in freshwater bodies triggered by eutrophication and climate change. Anatoxin-a is suspected to have a distinct toxic mechanism depending on physiological and nervous systems in exposed organisms. The numerous researches have been actively conducted with respect to the toxic effects of anatoxin-a on mammals; however, little research has aimed at its possible effects on aquatic plants, wherein well-structured nervous system is absent with the lack of various components of the acetylcholine mechanism. In this study, submerged macrophyte Ceratophyllum demersum (C. demersum) was adopted to examine the effects of anatoxin-a on morphological (growth), physiological (photosynthetic pigment contents) and biochemical (hydrogen peroxide level, biotransformation and antioxidative enzymes) responses in the aquatic plant at environmentally relevant concentrations (0.005, 0.05, 0.5, 5 and 50 μg/L). The significant elevation of antioxidative enzymes in parallel with increased formation of hydrogen peroxide appeared from 0.5 μg/L of anatoxin-a. In the measurement of photosynthetic pigments, the decrease in chlorophyll a content was detected at 5 and 50 μg/L, whereas the increase in carotenoids/total chlorophyll was observed from 0.05 μg/L. Accordingly, the alteration in growth was manifested in the presence of 5 and 50 μg/L of anatoxin-a. The results clearly indicate that anatoxin-a can disrupt homeostasis of C. demersum through induction of oxidative stress; furthermore this aquatic plant possesses effective defense mechanisms to cope with low concentrations of anatoxin-a.

Different strategies of cadmium detoxification in the submerged macrophyte Ceratophyllum demersum L.

The heavy metal cadmium (Cd) is highly toxic to plants. To understand the mechanisms of tolerance and resistance to Cd, we treated the rootless, submerged macrophyte Ceratophyllum demersum L. with sub-micromolar concentrations of Cd under environmentally relevant conditions. X-ray fluorescence measurements revealed changing distribution patterns of Cd and Zn at non-toxic (0.2 nM, 2 nM), moderately toxic (20 nM) and highly toxic (200 nM) levels of Cd. Increasing Cd concentrations led to enhanced sequestration of Cd into non-photosynthetic tissues like epidermis and vein. At toxic Cd concentrations, Zn was redistributed and mainly found in the vein. Cd treatment induced the synthesis of phytochelatins (PCs) in the plants, with a threshold of induction already at 20 nM Cd for PC3. In comparison, in plants treated with Cu, elevated PC levels were detected only at the highest concentrations (100-200 nM Cu). Our results show that also non-accumulators like C. demersum store toxic metals in tissues where the heavy metal interferes least with metabolic pathways, but remaining toxicity interferes with micronutrient distribution. Furthermore, we found that the induction of phytochelatins is not proportional to metal concentration, but has a distinct threshold, specific for each PC species. Finally we could show that 20 nM Cd, which was previously regarded as non-toxic to most plants, already induces detoxifying mechanisms.

Temporal variation of energy sources in a floodplain lake fish community

We compared the stable isotope ratios of δ 13C and δ 15N of four basal food sources and eight fish species collected in spring and summer from the largest freshwater lake in China, Lake Poyang. The aim was to study the temporal variations in the fishes’ energy sources. The δ 13C and δ 15N ratios of all eight species of fish were higher in summer. Employing the IsoSource mixing model, we identified that the terrestrial plant Carex spp. was the most important primary producer supporting fish biomass in spring when the water level was low; meanwhile, the submerged macrophyte Potamogeton malaianus made consistent contributions to fish. However, in summer, when the water level was high, the submerged macrophyte Ceratophyllum demersum was the most important primary production source for fish. Our study indicated that feeding links in floodplain lakes are complex and modified by hydrologic seasonality.

Arsenic accumulation and speciation in the submerged macrophyte Ceratophyllum demersum L.

Ceratophyllum demersum L. is a widespread submerged macrophyte in aquatic environments. Simulation experiments were conducted in the laboratory to investigate arsenic (As) accumulation, speciation, and efflux of C. demersum exposed to arsenate and arsenite solutions. Plant shoots showed a significant accumulation of As with a maximum of 862 and 963μgAsg(-1) dry weight after 4days of exposure to 10μM arsenate and arsenite, respectively. Regardless of whether arsenate or arsenite was supplied to the plants, arsenite was the predominant species in plant shoots. Furthermore, a dramatically higher influx rate of arsenate compared with arsenite was observed in C. demersum exposed to As solutions without the addition of phosphate (P). Arsenate uptake was considerably inhibited by P in this study, suggesting that arsenate is taken up by C. demersum via the phosphate transporters. However, arsenite uptake was unaffected by P and markedly reduced in the presence of glycerol and antimonite (Sb), indicating arsenite shares the aquaporin transport pathway. In addition, C. demersum rapidly reduces arsenate to arsenite in the shoot of the plant and extrudes most of them (>60%) to the external solutions. The efflux of arsenite was much higher than that of arsenate; the former is supposed to be both active and passive processes, and the latter through passive leakage. C. demersum is a strong As accumulator and an interesting model plant to study As uptake and metabolism due to the lack of a root-to-shoot translocation barrier.

Effects of the submerged macrophyte Ceratophyllum demersum L. on restoration of a eutrophic waterbody and its optimal coverage

In the paper, submerged macrophyte Ceratophyllum demersum L. was selected, and four simulation systems at 0, 20%, 33% and 50% restoration coverage (COV) were used to evaluate the purification effects of submerged macrophytes on restoration of a nutrient-polluted waterbody. The results showed that the water quality was improved significantly in the presence of C. demersum L. Specifically, turbidity and concentrations of TP, NH4+-N, Chl.a were reduced by more than 60%. PCA and Pearson's correlation analysis indicated a significant negative correlation between their reductions and COV of the C. demersum L. (P<0.05). ANOVAs and PCCA showed no significant differences among groups with different COV of C. demersum L. Based on comprehensive consideration, 20% is probably the optimal restoration coverage area for C. demersum L. in eutrophic shallow lakes.

Intraspecies differences in phenotypic plasticity: Invasive versus non-invasive populations of Ceratophyllum demersum

High phenotypic plasticity has been hypothesized to affect the invasiveness of plants, as high plasticity may enlarge the breath of environments in which the plants can survive and reproduce. Here we compare the phenotypic plasticity of invasive and non-invasive populations of the same species in response to growth temperature. Populations of the submerged macrophyte Ceratophyllum demersum from New Zealand, where the species is introduced and invasive, and from Denmark, where the species is native and non-invasive, were grown in a common garden setup at temperatures of 12, 18, 25 and 35 °C. We hypothesized that the phenotypic plasticity in fitness-related traits like growth and photosynthesis were higher in the invasive than in the non-invasive population. The invasive population acclimated to elevated temperatures through increased rates of photosynthesis (range: P amb: 8–452 μmol O 2 g −1 DM h −1) and relative growth rates (range: 0.01–0.05 d −1) and associated regulations in the photosynthetic machinery. The non-invasive population had a lower acclimation potential (range: P amb: 43–173 μmol O 2 g −1 DM h −1; RGR: 0.01–0.03 d −1), but was better at acclimating to cooler conditions by regulation of the light-harvesting complex. Hence, the invasive population of C. demersum from New Zealand had higher phenotypic plasticity in response to temperature than the non-invasive Danish population. This might be the result of genetic evolution since its introduction to New Zealand five decades ago, but further studies are needed to test this hypothesis. The study also indicate, that the global increase in temperature may exacerbate the problems experienced with the invasive C. demersum in New Zealand, as the performance and fitness of this population appear to be favoured at elevated temperatures.

Development and functional structure of epiphytic nematode communities on the submerged macrophyte Ceratophyllum demersum in Lake Sakadaš, Kopački Rit, Croatia

AbstractThe structural and functional diversity of epiphytic nematodes associated with the submerged macrophyte species, Ceratophyllum demersum, were investigated from July to September 2004 at three stations in the floodplain lake, Lake Sakadaš, Croatia. At stations I and II, C. demersum was dominant in the macrophyte patches. At station III, Myriophyllum spicatum was the dominant macrophyte species. When analysis of nematode species composition was done by grouping species with decreasing abundance, a community structure was evident on macrophytes that grew in different parts of the lake. When the abundance of nematodes was taken into account, C. demersum, which grew in different parts of the lake, was not associated with a unique nematode functional structure, and different trophic groups of nematodes were dominant at different stations. Eutobrilus nothus was the dominant nematode species for station I and chewers were the dominant functional group. Eutobrilus nothus, Eumonhystera sp. 1 and Eumonhystera filiformis vulgaris group were abundant nematode species for station II and consequently chewers and detritus feeders dominated at different periods of the investigation. Nematodes from station III were characterised by the highest nematode abundance where Chromadorina bioculata was the dominant species, and epistrate feeders were the dominant functional group. A part of our previously published results was reanalysed in this paper to enable comparison of nematode communities established on C. demersum with those developed on M. spicatum. There was no difference in the nematode functional structure between macrophyte species at the same station when the abundance of dominant species was taken into account, i.e., the same trophic structure was established.

Bioaccumulation and oxidative stress in submerged macrophyte Ceratophyllum demersum L. upon exposure to pyrene

Laboratory experiments were carried out to investigate pyrene bioaccumulation and its consequent biological responses in submerged macrophyte Ceratophyllum demersum. Plants were exposed to different levels (0.01, 0.02, 0.05, 0.07, 0.1 mg/L) of pyrene for 10 days, and the pyrene content, and total free radicals in plant were analyzed. The pyrene concentration in plant was highly correlated to exposure concentration (R(2)=0.990). Electron paramagnetic resonance (EPR) analysis revealed that pyrene exposure significantly increased total free radicals in the plants. A strong positive correlation (R(2)=0.956) between O(2)(*-) generation and pyrene contents implied that pyrene exposure induced reactive oxygen species (ROS) and led to oxidative stress in C. demersum. The activities of antioxidant enzymes and the contents of glutathione were determined. Change in the contents of malondialdehyde (MDA) was also studied. Results indicated that the bioaccumulation of pyrene resulted in the changes of the antioxidant defense system and the production of ROS with the oxidative stress, ultimately induced damnification in C. demersum.