No previous study has examined the large-scale distributional drivers of the entire global pool o... more No previous study has examined the large-scale distributional drivers of the entire global pool of 3,499 macrophyte species, despite the obvious importance of this for understanding the macroecology of these plants. To assess the hypothesis that natural rather than human-related transfer vectors act as the primary long-distance drivers of global movement of aquatic macrophytes, we analysed current macrophyte species distributions in relation to a set of human-related and natural transfer vectors. Most macrophytes (2,492 species: 71.2% of the global total) are endemic to a single ecozone, and generally lack the various functional adaptations needed for successful long-distance propagule transport. Such traits are, however, common in the 1,007 (28.8%) species native in > 1 ecozone. In total, 779 species (22.3%) are introduced, naturalised or invasive (I species) in one or more ecozones outwith their native range. The proportion of I species varies between ecozones and is best predicted by annual temperature and longitude. A migratory bird transfer vector and climatic variables strongly predict global native macrophyte species occurrence. Some native species of Miocene origin (or older) may have had their world distribution influenced by ancient vicariance events, while inter-ecozone hydrochory and Late Quaternary climate change are also relevant factors influencing a few species.
The presence of oxygen in lake sediments reduces sediment oxygen demand, and potentially improves... more The presence of oxygen in lake sediments reduces sediment oxygen demand, and potentially improves sediment phosphorus retention and coupled nitrification/denitrification. However, the release of oxygen from the roots of macrophytes has not previously been measured in highly reducing sediments. Here, in the highly reducing environments of a commercial garden soil and sediment from a hyper-eutrophic lake, we used nine oxygen optodes, placed onto scintillation vials to detect oxygen in the rhizosphere of Isoetes kirkii referred to as quillworts. We calculated rhizosphere metabolism using "night-time regression" a method designed to estimate stream metabolism at the reach scale. After the incubations, sediment was collected from each vial (with and without macrophytes) and was subjected to sequential phosphorus extractions. A lag period between light availability and increasing oxygen concentration, that varied between individual optodes, was used to improve the accuracy of metabolism estimates as it was postulated to represent the distance between the root and the optode. Higher sediment oxygen demand in the lake sediment caused I. kirkii to have higher root oxygen release than those plants grown in the garden soil and may have pushed plants in lake sediment close to their ability to survive. This was evident as a significant, negative relationship between root oxygen release and increasing sediment oxygen demand, indicating that if photosynthesis decreased or sediment oxygen demand increased, the plants would no longer being able to oxygenate the sediment surrounding their roots, which would likely lead to death. Finally, the presence of quillworts in lake sediments significantly increased stores of metal oxide and recalcitrant phosphorus in the lake sediment but not the garden soil.
The presence of invasive weed species invariably has a detrimental effect on native plant biodive... more The presence of invasive weed species invariably has a detrimental effect on native plant biodiversity, abundance and depth range in the short term and on native seed bank in the longer term. Removal of invasive weed beds may enable the recovery and restoration of native vegetation. The method or tools available for weed control include habitat manipulation and biological, chemical, mechanical, manual and integrated weed control. The selection of tools utilised for a particular weed issue are primarily dictated by the target weed species, characteristics of the lake or water body and the management goals. Management goals that target a significant reduction in weed biomass or eradication (in the longer term) and tools that result in selective target weed control provide opportunities for restoration of native aquatic plants. Restoration can occur via passive regeneration of native plants from adjacent sites, seed banks and waterfowl-mediated dispersal, or actively through planting, and brings associated benefits of habitat for native fauna, with additional improved amenity and recreation values.
Invasive aquatic plants constantly threaten freshwaters and associated environs globally. Water r... more Invasive aquatic plants constantly threaten freshwaters and associated environs globally. Water resource managers frequently seek new control tactics to combat invasive macrophytes, especially when the availability of herbicides registered for submersed plant control is limited. The synthetic auxin herbicide, florpyrauxifen-benzyl, recently registered (2018) for aquatic site applications in the United States, has shown success in controlling several invasive aquatic weeds. Studies were conducted to evaluate responses of native and invasive submersed plants to florpyrauxifen-benzyl under growth chamber conditions to provide insight on the selectivity of varying herbicide concentrations in New Zealand. Florpyrauxifen-benzyl concentrations evaluated ranged from 0.01 to 107.86 µg ai L−1, encompassing the maximum use concentration (48 µg L−1) for submersed plant applications. Dose–response metrics indicated the New Zealand native species watermilfoil [Myriophyllum triphyllum Orchard] was...
Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of U... more Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at.
ABSTRACT Thesis (D. Phil. Biological Sciences)--University of Waikato, 1997. Includes bibliograph... more ABSTRACT Thesis (D. Phil. Biological Sciences)--University of Waikato, 1997. Includes bibliographical references (leaves 281-299)
The use of biodegradable products as benthic barriers to control submerged aquatic weeds and thei... more The use of biodegradable products as benthic barriers to control submerged aquatic weeds and their impact on desirable native plant species was assessed in a common garden study. Five introduced invasive species (Ceratophyllum demersum, Egeria densa, Elodea canadensis, Hydrilla verticillata, Lagarosiphon major), a lesser weed (Potamogeton crispus, also introduced), and desirable native species (Myriophyllum triphyllum, Potamogeton ochreatus, an assemblage of charophytes, and oospore rich sediment) were grown in pots under common conditions before being covered by one of three matting products. Two different grades of hessian (burlap) and a coconut fiber product were placed over the plants and anchored in the pots. Plant emergence through the barrier and biomass were assessed over a 5-month period. For all species, the trend was toward reduced emergence with increasing product density, with significantly fewer plants emerging from treated pots compared with untreated control pots for...
The presence of invasive weed species invariably has a detrimental effect on native plant biodive... more The presence of invasive weed species invariably has a detrimental effect on native plant biodiversity, abundance and depth range in the short term and on native seed bank in the longer term. Removal of invasive weed beds may enable the recovery and restoration of native vegetation. The method or tools available for weed control include habitat manipulation and biological, chemical, mechanical, manual and integrated weed control. The selection of tools utilised for a particular weed issue are primarily dictated by the target weed species, characteristics of the lake or water body and the management goals. Management goals that target a significant reduction in weed biomass or eradication (in the longer term) and tools that result in selective target weed control provide opportunities for restoration of native aquatic plants. Restoration can occur via passive regeneration of native plants from adjacent sites, seed banks and waterfowl-mediated dispersal, or actively through planting, ...
Several invasive submersed aquatic plant species have established in many waterways within New Ze... more Several invasive submersed aquatic plant species have established in many waterways within New Zealand, causing substantial economic, recreational, and ecological impacts. The herbicides currently registered for use for the management of submersed aquatic plants do not control all aquatic weed species under field conditions, and additional control methods are sought. This study evaluates the effectiveness of flumioxazin against four target submersed species (Ceratophyllum demersum, Egeria densa, Lagarosiphon major, and Elodea canadensis) and three nontarget native species (Myriophyllum triphyllum, Potamogeton ochreatus, and Nitella sp. aff. cristata). Single applications of flumioxazin required high concentrations (400 lg ai L ) to reduce C. demersum and L. major biomass by at least 50% at pH 8.4, E. densa was not controlled effectively at any rate ( pH 8.4). However, low-rate applications (25, 50, 75, 100 lg ai L ) followed by high-rate applications (100, 200, 300, 400 lg ai L , re...
Introduced invasive alien aquatic plants (IAAPs) threaten ecosystems due to their excessive growt... more Introduced invasive alien aquatic plants (IAAPs) threaten ecosystems due to their excessive growth and have both ecological and economic impacts. To minimize these impacts, effective management of IAAPs is required according to national or international laws and regulations (e.g. the new EU regulation 1143/2014). Prevention of the introduction of IAAPs is considered the most cost effective management option. If/when prevention fails, early detection and rapid response increases the likelihood of eradication of the IAAPs and can minimize on-going management costs. For effective weed control (eradication and/or reduction), a variety of management techniques may be used. The goal or outcome of management interventions may vary depending on the site (i.e. a single waterbody, or a region with multiple waterbodies) and the feasibility of achieving the goal with the tools or methods available. Broadly defined management goals fall into three different categories of, containment, reduction or nuisance control and eradication. Management of IAAP utilises a range of control methods, either alone or in combination, to achieve a successful outcome. Here we review the biological, chemical and mechanical control methods for IAAPs, with a focus on the temperate and subtropical regions of the world and provide a management diagram illustrating the relationships between the state of the ecosystem, the management goals, outcomes and tools.
During a survey of submersed aquatic macrophytes and their associated fungi from lakes and waterw... more During a survey of submersed aquatic macrophytes and their associated fungi from lakes and waterways in New Zealand’s North Island, an isolate of Mycoleptodiscus terrestris (Gerd.) Ostaz. was confirmed on the basis of colony characteristics, sporodochia, and conidial morphology. This is a new record of M. terrestris in New Zealand and a new host species, the introduced aquatic macrophyte, Ceratophyllum
No previous study has examined the large-scale distributional drivers of the entire global pool o... more No previous study has examined the large-scale distributional drivers of the entire global pool of 3,499 macrophyte species, despite the obvious importance of this for understanding the macroecology of these plants. To assess the hypothesis that natural rather than human-related transfer vectors act as the primary long-distance drivers of global movement of aquatic macrophytes, we analysed current macrophyte species distributions in relation to a set of human-related and natural transfer vectors. Most macrophytes (2,492 species: 71.2% of the global total) are endemic to a single ecozone, and generally lack the various functional adaptations needed for successful long-distance propagule transport. Such traits are, however, common in the 1,007 (28.8%) species native in > 1 ecozone. In total, 779 species (22.3%) are introduced, naturalised or invasive (I species) in one or more ecozones outwith their native range. The proportion of I species varies between ecozones and is best predicted by annual temperature and longitude. A migratory bird transfer vector and climatic variables strongly predict global native macrophyte species occurrence. Some native species of Miocene origin (or older) may have had their world distribution influenced by ancient vicariance events, while inter-ecozone hydrochory and Late Quaternary climate change are also relevant factors influencing a few species.
The presence of oxygen in lake sediments reduces sediment oxygen demand, and potentially improves... more The presence of oxygen in lake sediments reduces sediment oxygen demand, and potentially improves sediment phosphorus retention and coupled nitrification/denitrification. However, the release of oxygen from the roots of macrophytes has not previously been measured in highly reducing sediments. Here, in the highly reducing environments of a commercial garden soil and sediment from a hyper-eutrophic lake, we used nine oxygen optodes, placed onto scintillation vials to detect oxygen in the rhizosphere of Isoetes kirkii referred to as quillworts. We calculated rhizosphere metabolism using "night-time regression" a method designed to estimate stream metabolism at the reach scale. After the incubations, sediment was collected from each vial (with and without macrophytes) and was subjected to sequential phosphorus extractions. A lag period between light availability and increasing oxygen concentration, that varied between individual optodes, was used to improve the accuracy of metabolism estimates as it was postulated to represent the distance between the root and the optode. Higher sediment oxygen demand in the lake sediment caused I. kirkii to have higher root oxygen release than those plants grown in the garden soil and may have pushed plants in lake sediment close to their ability to survive. This was evident as a significant, negative relationship between root oxygen release and increasing sediment oxygen demand, indicating that if photosynthesis decreased or sediment oxygen demand increased, the plants would no longer being able to oxygenate the sediment surrounding their roots, which would likely lead to death. Finally, the presence of quillworts in lake sediments significantly increased stores of metal oxide and recalcitrant phosphorus in the lake sediment but not the garden soil.
The presence of invasive weed species invariably has a detrimental effect on native plant biodive... more The presence of invasive weed species invariably has a detrimental effect on native plant biodiversity, abundance and depth range in the short term and on native seed bank in the longer term. Removal of invasive weed beds may enable the recovery and restoration of native vegetation. The method or tools available for weed control include habitat manipulation and biological, chemical, mechanical, manual and integrated weed control. The selection of tools utilised for a particular weed issue are primarily dictated by the target weed species, characteristics of the lake or water body and the management goals. Management goals that target a significant reduction in weed biomass or eradication (in the longer term) and tools that result in selective target weed control provide opportunities for restoration of native aquatic plants. Restoration can occur via passive regeneration of native plants from adjacent sites, seed banks and waterfowl-mediated dispersal, or actively through planting, and brings associated benefits of habitat for native fauna, with additional improved amenity and recreation values.
Invasive aquatic plants constantly threaten freshwaters and associated environs globally. Water r... more Invasive aquatic plants constantly threaten freshwaters and associated environs globally. Water resource managers frequently seek new control tactics to combat invasive macrophytes, especially when the availability of herbicides registered for submersed plant control is limited. The synthetic auxin herbicide, florpyrauxifen-benzyl, recently registered (2018) for aquatic site applications in the United States, has shown success in controlling several invasive aquatic weeds. Studies were conducted to evaluate responses of native and invasive submersed plants to florpyrauxifen-benzyl under growth chamber conditions to provide insight on the selectivity of varying herbicide concentrations in New Zealand. Florpyrauxifen-benzyl concentrations evaluated ranged from 0.01 to 107.86 µg ai L−1, encompassing the maximum use concentration (48 µg L−1) for submersed plant applications. Dose–response metrics indicated the New Zealand native species watermilfoil [Myriophyllum triphyllum Orchard] was...
Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of U... more Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at.
ABSTRACT Thesis (D. Phil. Biological Sciences)--University of Waikato, 1997. Includes bibliograph... more ABSTRACT Thesis (D. Phil. Biological Sciences)--University of Waikato, 1997. Includes bibliographical references (leaves 281-299)
The use of biodegradable products as benthic barriers to control submerged aquatic weeds and thei... more The use of biodegradable products as benthic barriers to control submerged aquatic weeds and their impact on desirable native plant species was assessed in a common garden study. Five introduced invasive species (Ceratophyllum demersum, Egeria densa, Elodea canadensis, Hydrilla verticillata, Lagarosiphon major), a lesser weed (Potamogeton crispus, also introduced), and desirable native species (Myriophyllum triphyllum, Potamogeton ochreatus, an assemblage of charophytes, and oospore rich sediment) were grown in pots under common conditions before being covered by one of three matting products. Two different grades of hessian (burlap) and a coconut fiber product were placed over the plants and anchored in the pots. Plant emergence through the barrier and biomass were assessed over a 5-month period. For all species, the trend was toward reduced emergence with increasing product density, with significantly fewer plants emerging from treated pots compared with untreated control pots for...
The presence of invasive weed species invariably has a detrimental effect on native plant biodive... more The presence of invasive weed species invariably has a detrimental effect on native plant biodiversity, abundance and depth range in the short term and on native seed bank in the longer term. Removal of invasive weed beds may enable the recovery and restoration of native vegetation. The method or tools available for weed control include habitat manipulation and biological, chemical, mechanical, manual and integrated weed control. The selection of tools utilised for a particular weed issue are primarily dictated by the target weed species, characteristics of the lake or water body and the management goals. Management goals that target a significant reduction in weed biomass or eradication (in the longer term) and tools that result in selective target weed control provide opportunities for restoration of native aquatic plants. Restoration can occur via passive regeneration of native plants from adjacent sites, seed banks and waterfowl-mediated dispersal, or actively through planting, ...
Several invasive submersed aquatic plant species have established in many waterways within New Ze... more Several invasive submersed aquatic plant species have established in many waterways within New Zealand, causing substantial economic, recreational, and ecological impacts. The herbicides currently registered for use for the management of submersed aquatic plants do not control all aquatic weed species under field conditions, and additional control methods are sought. This study evaluates the effectiveness of flumioxazin against four target submersed species (Ceratophyllum demersum, Egeria densa, Lagarosiphon major, and Elodea canadensis) and three nontarget native species (Myriophyllum triphyllum, Potamogeton ochreatus, and Nitella sp. aff. cristata). Single applications of flumioxazin required high concentrations (400 lg ai L ) to reduce C. demersum and L. major biomass by at least 50% at pH 8.4, E. densa was not controlled effectively at any rate ( pH 8.4). However, low-rate applications (25, 50, 75, 100 lg ai L ) followed by high-rate applications (100, 200, 300, 400 lg ai L , re...
Introduced invasive alien aquatic plants (IAAPs) threaten ecosystems due to their excessive growt... more Introduced invasive alien aquatic plants (IAAPs) threaten ecosystems due to their excessive growth and have both ecological and economic impacts. To minimize these impacts, effective management of IAAPs is required according to national or international laws and regulations (e.g. the new EU regulation 1143/2014). Prevention of the introduction of IAAPs is considered the most cost effective management option. If/when prevention fails, early detection and rapid response increases the likelihood of eradication of the IAAPs and can minimize on-going management costs. For effective weed control (eradication and/or reduction), a variety of management techniques may be used. The goal or outcome of management interventions may vary depending on the site (i.e. a single waterbody, or a region with multiple waterbodies) and the feasibility of achieving the goal with the tools or methods available. Broadly defined management goals fall into three different categories of, containment, reduction or nuisance control and eradication. Management of IAAP utilises a range of control methods, either alone or in combination, to achieve a successful outcome. Here we review the biological, chemical and mechanical control methods for IAAPs, with a focus on the temperate and subtropical regions of the world and provide a management diagram illustrating the relationships between the state of the ecosystem, the management goals, outcomes and tools.
During a survey of submersed aquatic macrophytes and their associated fungi from lakes and waterw... more During a survey of submersed aquatic macrophytes and their associated fungi from lakes and waterways in New Zealand’s North Island, an isolate of Mycoleptodiscus terrestris (Gerd.) Ostaz. was confirmed on the basis of colony characteristics, sporodochia, and conidial morphology. This is a new record of M. terrestris in New Zealand and a new host species, the introduced aquatic macrophyte, Ceratophyllum
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