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Elisabeth S Bakker - One of the best experts on this subject based on the ideXlab platform.
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species identity and diversity effects on invasion resistance of tropical Freshwater Plant communities
Scientific Reports, 2020Co-Authors: Antonella Petruzzella, Tauany A Da S S R Rodrigues, Casper H A Van Leeuwen, Francisco De Assis Esteves, Marcos Paulo Figueiredobarros, Elisabeth S BakkerAbstract:Biotic resistance mediated by native Plant diversity has long been hypothesized to reduce the success of invading Plant species in terrestrial systems in temperate regions. However, still little is known about the mechanisms driving invasion patterns in other biomes or latitudes. We help to fill this gap by investigating how native Plant community presence and diversity, and the presence of native phylogenetically closely related species to an invader, would affect invader Hydrilla verticillata establishment success in tropical Freshwater submerged Plant communities. The presence of a native community suppressed the growth of H. verticillata, but did not prevent its colonisation. Invader growth was negatively affected by native Plant productivity, but independent of native species richness and phylogenetic relatedness to the invader. Native Plant production was not related to native species richness in our study. We show that resistance in these tropical aquatic submerged Plant communities is mainly driven by the presence and biomass of a native community independent of native species diversity. Our study illustrates that resistance provided by these tropical Freshwater submerged Plant communities to invasive species contrasts to resistance described for other ecosystems. This emphasizes the need to include understudied systems when predicting patterns of species invasiveness and ecosystem invasibility across biomes.
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the ecology of Plant secondary metabolites the role of Plant secondary metabolites in Freshwater macrophyte herbivore interactions
2012Co-Authors: Elisabeth M Gross, Elisabeth S BakkerAbstract:Introduction Historically, herbivory on aquatic Plants has been considered negligible. ‘One could probably remove all the larger Plants and substitute glass structures of the same form and surface texture without greatly affecting the immediate food relations’, wrote Shelford (1918), cited in Hutchinson (1975) about grazing losses of submerged angiosperms. This misconception might have persisted for so long because grazing by zooplankton on phytoplankton has been the major focus in limnology for decades. Also, herbivore-related biomass losses of higher aquatic Plants were estimated to be less than 10% of the total production (Wetzel, 1983). In the past two decades many studies have shown that multiple invertebrate and vertebrate herbivores feed on Freshwater angiosperms and that herbivory on vascular Plants is quantitatively equally important in terrestrial and Freshwater habitats (Lodge, 1991; Newman, 1991; Cyr & Pace, 1993). Thus, we are now ready to critically consider the role of Plant secondary metabolites (PSMs) in Freshwater Plant–herbivore interactions. Whereas the importance and tremendous variety of PSMs is well acknowledged in terrestrial Plants and seaweeds, relatively little is known about the presence, levels, types and function of PSMs in Freshwater Plants (Lodge et al ., 1998; Sotka et al ., 2009). This is surprising because aquatic angiosperms and most of their insect herbivores are in fact secondarily aquatic, descendant from terrestrial ancestors (Newman, 1991). Thus, similarities in potential feeding deterrents and host-Plant selection might be anticipated. Yet there may also be pronounced differences in Plant–herbivore interactions in the aquatic environment. For example, water provides different physico-chemical conditions compared with air or soil, which should affect the dispersal of released compounds. Additionally, not all terrestrial Plant families and growth forms have relatives underwater, and aquatic herbivores differ in species composition and diet selection from their terrestrial counterparts. These environmental, phylogenetic and ecological predispositions might have shaped the kinds of feeding deterrents that are present in Freshwater systems.
Jennifer L Stauber - One of the best experts on this subject based on the ideXlab platform.
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chronic toxicity of the herbicide tebuthiuron to the tropical green alga chlorella sp and the duckweed lemna aequinoctialis
2004Co-Authors: Cecil Camilleri, Christina Turley, M T Binet, Jennifer L StauberAbstract:The substituted urea herbicide, tebuthiuron, has been commonly used in northern Australia to control the invasive wetland weed, Mimosa pigra. This study assessed the chronic toxicity of tebuthiuron to two non-target tropical Freshwater Plant species, the green alga, Chlorella sp (72-h cell division rate) and the duckweed, Lemna aequinoctialis (96-h Plant growth rate). One range-finding and two definitive experiments were carried out for both species, with the definitive tests covering a concentration range of 50 to 1000 µg/L for Chlorella sp and 5 to 3200 µg/L for L. aequinoctialis. The (geometric) mean IC20, IC50, LOEC and NOEC values from both definitive tests were 171, 281, 197 and 101 µg/L, respectively, for Chlorella sp, and 76, 181, 101 and 49 µg/L, respectively, for L. aequinoctialis. L. aequinoctialis was more sensitive than Chlorella sp to low tebuthiuron concentrations, although Chlorella sp exhibited complete (ie. >90%) inhibition of growth at a lower concentration (~400 µg/L) than L. aequinoctialis (~800 µg/L). Both species were similarly sensitive to tebuthiuron as northern hemisphere, temperate Freshwater Plant species, but were approximately three orders of magnitude more sensitive than Australian tropical Freshwater animal species. It is anticipated that the tropical Freshwater Plant chronic toxicity data presented in this study will be incorporated into future revisions of the Australian water quality guidelines for tebuthiuron.
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chronic toxicity of the herbicide tebuthiuron to the tropical green alga chlorella sp and the duckweed lemna aequinoctialis
2004Co-Authors: Caroline Camilleri, Carol Turley, M T Binet, Jennifer L StauberAbstract:The substituted urea herbicide, tebuthiuron, has been commonly used in northern Australia to control the invasive wetland weed, Mimosa pigra. This study assessed the chronic toxicity of tebuthiuron to two non-target tropical Freshwater Plant species, the green alga, Chlorella sp (72-h cell division rate) and the duckweed, Lemna aequinoctialis (96-h Plant growth rate). One range-finding and two definitive experiments were carried out for both species, with the definitive tests covering a concentration range of 50 to 1000 µg/L for Chlorella sp and 5 to 3200 µg/L for L. aequinoctialis. The (geometric) mean IC20, IC50, LOEC and NOEC values from both definitive tests were 171, 281, 197 and 101 µg/L, respectively, for Chlorella sp, and 76, 181, 101 and 49 µg/L, respectively, for L. aequinoctialis. L. aequinoctialis was more sensitive than Chlorella sp to low tebuthiuron concentrations, although Chlorella sp exhibited complete (ie. >90%) inhibition of growth at a lower concentration (~400 µg/L) than L. aequinoctialis (~800 µg/L). Both species were similarly sensitive to tebuthiuron as northern hemisphere, temperate Freshwater Plant species, but were approximately three orders of magnitude more sensitive than Australian tropical Freshwater animal species. It is anticipated that the tropical Freshwater Plant chronic toxicity data presented in this study will be incorporated into future revisions of the Australian water quality guidelines for tebuthiuron.
Elisabeth M Gross - One of the best experts on this subject based on the ideXlab platform.
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the ecology of Plant secondary metabolites the role of Plant secondary metabolites in Freshwater macrophyte herbivore interactions
2012Co-Authors: Elisabeth M Gross, Elisabeth S BakkerAbstract:Introduction Historically, herbivory on aquatic Plants has been considered negligible. ‘One could probably remove all the larger Plants and substitute glass structures of the same form and surface texture without greatly affecting the immediate food relations’, wrote Shelford (1918), cited in Hutchinson (1975) about grazing losses of submerged angiosperms. This misconception might have persisted for so long because grazing by zooplankton on phytoplankton has been the major focus in limnology for decades. Also, herbivore-related biomass losses of higher aquatic Plants were estimated to be less than 10% of the total production (Wetzel, 1983). In the past two decades many studies have shown that multiple invertebrate and vertebrate herbivores feed on Freshwater angiosperms and that herbivory on vascular Plants is quantitatively equally important in terrestrial and Freshwater habitats (Lodge, 1991; Newman, 1991; Cyr & Pace, 1993). Thus, we are now ready to critically consider the role of Plant secondary metabolites (PSMs) in Freshwater Plant–herbivore interactions. Whereas the importance and tremendous variety of PSMs is well acknowledged in terrestrial Plants and seaweeds, relatively little is known about the presence, levels, types and function of PSMs in Freshwater Plants (Lodge et al ., 1998; Sotka et al ., 2009). This is surprising because aquatic angiosperms and most of their insect herbivores are in fact secondarily aquatic, descendant from terrestrial ancestors (Newman, 1991). Thus, similarities in potential feeding deterrents and host-Plant selection might be anticipated. Yet there may also be pronounced differences in Plant–herbivore interactions in the aquatic environment. For example, water provides different physico-chemical conditions compared with air or soil, which should affect the dispersal of released compounds. Additionally, not all terrestrial Plant families and growth forms have relatives underwater, and aquatic herbivores differ in species composition and diet selection from their terrestrial counterparts. These environmental, phylogenetic and ecological predispositions might have shaped the kinds of feeding deterrents that are present in Freshwater systems.
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degradation of gallic acid and hydrolysable polyphenols is constitutively activated in the Freshwater Plant associated bacterium matsuebacter sp fb25
Aquatic Microbial Ecology, 2007Co-Authors: Nicolai Muller, Melanie Hempel, Bodo Philipp, Elisabeth M GrossAbstract:Hydrolysable polyphenols are present in Myriophyllum spicatum L. at high concentra- tions of up to 25% of dry matter and are also excreted. Bacteria associated with the submerged macrophyte M. spicatum isolated from the surrounding water column and epiphytic biofilm were tested for their ability to degrade polyphenols. Several bacterial isolates were capable of growing with tannic acid as the sole carbon and energy source, among them Matsuebacter sp. FB25, Agrobac- terium vitis EB26 and Pseudomonas sp. FB22. Cell suspensions of Matsuebacter sp. precultured on succinate were capable of degrading gallic acid, while those of A. vitis were not, indicating the con- stitutive presence of gallate-degrading enzymes in the former. When cells were precultured on gal- lic or tannic acid, cell suspensions of both strains exhibited an enhanced degradation rate of gallic acid. M. spicatum-derived hydrolysable polyphenols, which are comparable in structure to tannic acid, resulted in the same enhanced degradation rate of gallic acid or tellimagrandin II, the major M. spicatum polyphenol, by cell suspensions of Matsuebacter sp. FB25. The presence of polyphenol- degrading bacteria in the vicinity of M. spicatum explains the observed fast disappearance of tellima- grandin II and other hydrolysable polyphenols after excretion and has implications for allelochemical interference with competitors, herbivores and potential pathogenic microorganisms. The presence of Matsuebacter sp. and other polyphenol-degrading strains in such environments suggests a suffi- ciently strong effect of M. spicatum exudates to bring about selection in favour of highly specialised bacteria.
Huang Wenmin - One of the best experts on this subject based on the ideXlab platform.
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Structural basis for C4 photosynthesis without Kranz anatomy in leaves of the submerged Freshwater Plant Ottelia alismoides
'Oxford University Press (OUP)', 2020Co-Authors: Han Shijuan, Maberly Stephen, Gontero Brigitte, Xing Zhenfei, Li Wei, Jiang Hongsheng, Huang WenminAbstract:International audienceBackground and AimsOttelia alismoides (Hydrocharitaceae) is a Freshwater macrophyte that, unusually, possesses three different CO2-concentrating mechanisms. Here we describe its leaf anatomy and chloroplast ultrastructure, how these are altered by CO2 concentration and how they may underlie C4 photosynthesis.MethodsLight and transmission electron microscopy were used to study the anatomy of mature leaves of O. alismoides grown at high and low CO2 concentrations. Diel acid change and the activity of phosphoenolpyruvate carboxylase were measured to confirm that CAM activity and C4 photosynthesis were present.Key ResultsWhen O. alismoides was grown at low CO2, the leaves performed both C4 and CAM photosynthesis whereas at high CO2 leaves used C4 photosynthesis. The leaf comprised an upper and lower layer of epidermal cells separated by a large air space occupying about 22 % of the leaf transverse-section area, and by mesophyll cells connecting the two epidermal layers. Kranz anatomy was absent. At low CO2, chloroplasts in the mesophyll cells were filled with starch even at the start of the photoperiod, while epidermal chloroplasts contained small starch grains. The number of chloroplasts in the epidermis was greater than in the mesophyll cells. At high CO2, the structure was unchanged but the thicknesses of the two epidermal layers, the air space, mesophyll and the transverse-section area of cells and air space were greater.ConclusionsLeaves of O. alismoides have epidermal and mesophyll cells that contain chloroplasts and large air spaces but lack Kranz anatomy. The high starch content of mesophyll cells suggests they may benefit from an internal source of CO2, for example via C4 metabolism, and are also sites of starch storage. The air spaces may help in the recycling of decarboxylated or respired CO2. The structural similarity of leaves at low and high CO2 is consistent with the constitutive nature of bicarbonate and C4 photosynthesis. There is sufficient structural diversity within the leaf of O. alismoides to support dual-cell C4 photosynthesis even though Kranz anatomy is absent
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Structural basis for C4 photosynthesis without Kranz anatomy in leaves of the submerged Freshwater Plant Ottelia alismoides
'Oxford University Press (OUP)', 2020Co-Authors: Han Shijuan, Gontero Brigitte, Xing Zhenfei, Li Wei, Jiang Hongsheng, Maberly, Stephen C., Huang WenminAbstract:Background and Aims: Ottelia alismoides (Hydrocharitaceae) is a Freshwater macrophyte that, unusually, possesses three different CO2-concentrating mechanisms. Here we describe its leaf anatomy and chloroplast ultrastructure, how these are altered by CO2 concentration and how they may underlie C4 photosynthesis. Methods: Light and transmission electron microscopy were used to study the anatomy of mature leaves of O. alismoides grown at high and low CO2 concentrations. Diel acid change and the activity of phosphoenolpyruvate carboxylase were measured to confirm that CAM activity and C4 photosynthesis were present. Key Results: When O. alismoides was grown at low CO2, the leaves performed both C4 and CAM photosynthesis whereas at high CO2 leaves used C4 photosynthesis. The leaf comprised an upper and lower layer of epidermal cells separated by a large air space occupying about 22 % of the leaf transverse-section area, and by mesophyll cells connecting the two epidermal layers. Kranz anatomy was absent. At low CO2, chloroplasts in the mesophyll cells were filled with starch even at the start of the photoperiod, while epidermal chloroplasts contained small starch grains. The number of chloroplasts in the epidermis was greater than in the mesophyll cells. At high CO2, the structure was unchanged but the thicknesses of the two epidermal layers, the air space, mesophyll and the transverse-section area of cells and air space were greater. Conclusions: Leaves of O. alismoides have epidermal and mesophyll cells that contain chloroplasts and large air spaces but lack Kranz anatomy. The high starch content of mesophyll cells suggests they may benefit from an internal source of CO2, for example via C4 metabolism, and are also sites of starch storage. The air spaces may help in the recycling of decarboxylated or respired CO2. The structural similarity of leaves at low and high CO2 is consistent with the constitutive nature of bicarbonate and C4 photosynthesis. There is sufficient structural diversity within the leaf of O. alismoides to support dual-cell C4 photosynthesis even though Kranz anatomy is absent
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Structural basis for C-4 photosynthesis without Kranz anatomy in leaves of the submerged Freshwater Plant Ottelia alismoides
'Oxford University Press (OUP)', 2020Co-Authors: Han Shijuan, Gontero Brigitte, Xing Zhenfei, Li Wei, Jiang Hongsheng, Maberly, Stephen C., Huang WenminAbstract:Background and Aims: Ottelia alismoides (Hydrocharitaceae) is a Freshwater macrophyte that, unusually. possesses three different CO3-concentrating mechanisms. Here we describe its leaf anatomy and chloroplast ultrastructure, how these are altered by CO2 concentration and how they may underlie C-4 photosynthesis. Methods: Light and transmission electron microscopy were used to study the anatomy of mature leaves of O. alismoides grown at high and low CO2 concentrations. Diel acid change and the activity of phosphoenolpyruvate carboxylase were measured to confirm that CAM activity and C-4 photosynthesis were present. Key Results: When O. alismoides was grown at low CO2, the leaves performed both C-4 and CAM photosynthesis whereas at high CO2 leaves used C-4 photosynthesis. The leaf comprised an upper and lower layer of epidermal cells separated by a large air space occupying about 22 % of the leaf transverse-section area, and by mesophyll cells connecting the two epidermal layers. Kranz anatomy was absent. At low CO2, chloroplasts in the mesophyll cells were filled with starch even at the start of the photoperiod, while epidermal chloroplasts contained small starch grains. The number of chloroplasts in the epidermis was greater than in the mesophyll cells. At high CO2, the structure was unchanged but the thicknesses of the two epidermal layers, the air space, mesophyll and the transverse-section area of cells and air space were greater. Conclusions: Leaves of O. alismoides have epidermal and mesophyll cells that contain chloroplasts and large air spaces but lack Kranz anatomy. The high starch content of mesophyll cells suggests they may benefit from an internal source of CO2, for example via C-4 metabolism, and arc also sites of starch storage. The air spaces may help in the recycling of decarboxylated or respired CO2. The structural similarity of leaves at low and high CO2 is consistent with the constitutive nature of bicarbonate and C-4 photosynthesis. There is sufficient structural diversity within the leaf of O. alismoides to support dual-cell C-4 photosynthesis even though Kranz anatomy is absent
Frede Ostergaard Andersen - One of the best experts on this subject based on the ideXlab platform.
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a multidisciplinary approach to understanding the recent and historical occurrence of the Freshwater Plant littorella uniflora
Freshwater Biology, 2006Co-Authors: Ole Birger Pedersen, Troels Andersen, Kou Ikejima, Zakir Hossain, Frede Ostergaard AndersenAbstract:SUMMARY 1. The vulnerability of softwater, oligotrophic lakes to eutrophication has caused the disappearance of many, if not most, of the unique isoetid Plant communities. We tested whether the presence or disappearance of the isoetid Littorella uniflora (L.) could be predicted from environmental parameters, soil types and land use in the catchment area, and atmospheric nitrogen deposition. 2. We found that the topographic catchment area of a lake was an irrelevant unit to study effects of soil type and land use. Instead, using a GIS-generated buffer zone around the lakes it proved feasible to classify 472 lakes into historical (if L. uniflora had disappeared) or recent (if L. uniflora was still present) Littorella lakes, based on soil type and land use. Our analysis showed that aeolian sand deposits and heath in the buffer zone favoured the presence of L. uniflora, whereas moraine clay and agriculture were strongly linked to the disappearance of L. uniflora. 3. However, in order to understand fully the presence or disappearance of L. uniflora, environmental data were needed in addition to soil types, land use and nitrogen deposition, and the use of discriminant analysis allowed us to classify 96% of the investigated lakes correctly into recent or historical sites. Alkalinity, total phosphorus, total nitrogen, aeolian sand deposits and heath were the most important parameters explaining the presence or disappearance of L. uniflora. Our analysis also indicated that eutrophication, rather than acidification, has likely caused the disappearance of L. uniflora from 218 of the 472 lakes investigated. 4. Our findings have widespread implications for the conservation or restoration of isoetid habitats and we recommend applying a wide buffer zone around lakes, with restrictions on farming and traditional forestry activities. In addition, our buffering concept may prove a useful tool for aquatic ecologists to investigate relationships between catchment features and organisms (Plants, insects and amphibians) with aquatic as well as terrestrial life forms.
