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16th International Symposium on Aquatic Plants

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Session 1 

Topic: Aquatic plants and macroecology

Chair: Janne Alahuhta

Short description: Session focuses on aquatic plant diversity patterns and processes across broad spatial and temporal scales. It extends the traditional botanical viewpoint to ecological and biogeographical perspective. Session presents topical research on broad-scale diversity and dispersal patterns, and research made available by increasing amount of data. Regional and global scale environmental problems, such as global change, have created a need for broad-scale studies that are addressed in this session.


Session 2 

Topic: Plant-animal interactions in aquatic plant beds

Chair: Elisabeth Bakker Co-chair: Jonas Schoelynck

Short description: Aquatic plants are food for herbivores and omnivores and thus part of the aquatic food web. However, they are as important as providers of habitat to other organisms. Therefore, aquatic plants play a crucial role in the conservation and restoration of riparian and benthic habitats. With ongoing global change, including eutrophication, exotic species proliferation and climate change, the properties of the plant beds may change as well as the plant-animal interactions that take place within the beds. Alternatively, restoration may make use of plant properties to attract animals whereas the animals in turn may consume the restored plant beds. This session welcomes contributions on the interactions between plants and animals, both trophic and non-trophic, to advance our understanding of the fundamental aspects of plant-animal interactions under water and in wetland vegetation and address emergent properties of plant-animal interactions in a restoration or global change context.


Session 3 

Topic: Global change threats to oligotrophic lake vegetation

Chair: Esperanca Gacia

Short description: Biodiversity loss is dramatic in aquatic vegetation particularly from pristine oligotrophic systems. Factors such as eutrophication, acidification, changes in land use and invasions, are among the main causes. In this session we will approach scenarios of threats, encourage regional diagnoses and welcome discussion on management actions to preserve aquatic plants from oligotrophic continental water bodies.


Session 4 

Topic: Causes and patterns of macrophyte decline and recovery

Chair: Sabine Hilt & Andreas Hussner

Short description: In many freshwater bodies, the abundance and community composition of submerged and/or floating macrophytes is of key importance for several ecosystems functions such as habitat, nutrient retention or carbon processing. Understanding the causes and patterns of changes in macrophyte communities is thus crucial for a sustainable management of these water bodies and their functions. In recent decades, a number of general concepts have been developed, such as regime shifts between alternative stable states in eutrophic shallow lakes and lowland rivers, the occurrence of crashing/recovery states or boom-bust cycles of invasive species. Yet we are still far from understanding the complex patterns and causes of spatial and temporal changes in macrophyte communities. A pelagic focus in limnological research and a lack of macrophyte data in sufficient temporal and spatial resolution have been reasons for this knowledge gap. However, recent developments in macrophyte monitoring due to legislation (e.g. EU Water Framework Directive) and new methods (remote sensing, hydroacoustics) have improved this situation and allow for new insights. In this session, we welcome fundamental and applied contributions with a mechanistic or methodological focus on causes and patterns of macrophytes decline and recovery at all spatial and temporal scales.
Key session objectives:
• Unravel patterns of shifts in macrophyte abundance and community composition
• Identify key drivers for shifts in macrophyte abundance and community composition


Session 5 

Topic: Aquatic plant ecophyisology

Chair: Brian Sorrell

Short description: The diversity of aquatic vegetation is strongly related to specific physiological adaptations to a variety of environmental factors. This session will include presentations on ecophysiological processes in aquatic macrophytes ensuring their survival, growth and distribution in aquatic environments. These relate to the particular challenges faced by aquatic plants in relation to light and inorganic carbon limitation for photosynthesis, and oxygen deprivation and anaerobic stress and its avoidance. Topics will include, but are not limited to, carbon concentrating mechanisms, gas exchange and gas transport processes, and the relevant morphological and anatomical traits.


Session 6

Topic: Friends or foes: Wanted and unwanted effects of herbicides on aquatic plants

Chair: Elisabeth Gross, Gertie Arts, Ryan Thum

Short description: Herbicides may affect aquatic plant performance unintentionally or through targeted action. Their use in aquatic systems underlies dissimilar regulation in different parts of the world. In Europe, the Water Framework and Pesticide Directive provides the guideline to limit the impact of herbicides and other anthropogenic pollutants on water bodies. In the US, the Environmental Protection Agency (EPA) and relevant state authorities regulate herbicide use, but application in water bodies can be allowed as a decisive tool to control invasive alien aquatic plants. For the admission of herbicides on the market, a dossier needs to be submitted based on – mostly – short-term experiments with standard primary producer species (algae and aquatic macrophytes). What is missing in our understanding of effects of herbicides on aquatic plants, are long-term effects, e.g. carry-over effects to the next season or effects on the recovery and competitive ability of aquatic macrophytes. This understanding is key in order to understand effects of herbicides at the ecosystem level. This session intends to bring together the different views and to provide a platform to outline known targeted and side effects of herbicide use in freshwater systems.
Key session objectives:
1) To bridge ecotoxicology and aquatic plant ecology
2) To assess the role of herbicides and other anthropogenic pollutants in aquatic plant decline


Session 7

Topic: Management of macrophytes

Chair: Deborah Hofstra. Co-chair: Tony Dugdale

Short description: Aquatic plants play a substantial role in the functioning of aquatic ecosystems, but some macrophytes, mostly alien species, are invasive and have significant ecological and economic impacts. Alien invasive species are considered second only to habitat loss as the drivers of biodiversity decline in freshwaters globally. Their impacts are additional to other stressors on the aquatic environment, often operating independently from them and escalating over time in the absence of management. The selection of an appropriate management option that will decrease negative effects of invasive macrophytes is largely dependent on the species, the size of the invaded area, and the outcome sought. The outcomes sought by management agencies may be driven by legislative requirements, the need to protect biodiversity, rare or threatened species habitat, and are increasingly related to the risks as perceived and accepted by the public. To successfully manage the threats and mitigate the impacts of invasive aquatic weeds, science is challenged to develop tools and approaches that can be implemented within a complex range of aquatic environments, will provide predictable outcomes, within appropriate timeframes and at scale. This session welcomes papers on all aspects of invasive macrophyte management, with a focus on approaches that provide tangible gains in terms of improved ecosystem health and function.


Session 8 

Topic: Aquatic plants research and conservation in Mediterranean ecosystems

Chair: Eva Papastergiadou

Short description: Mediterranean ecosystems have a long history of human disturbances and water scarcity exacerbates pressures around water bodies (i.e. morphological changes, water abstraction, irregular water flow, pollution, eutrophication, water logging, and leisure activities). Ecosystems in warm climates are more sensitive to anthropogenic pressures, such as eutrophication and water extraction, than similar ecosystems in temperate or cold climates. In this session, we welcome submissions addressing the factors that influence aquatic macrophytes richness, diversity, and abundance and habitat features, as well as management and conservation issues in Mediterranean and other warm climate ecosystems (e.g. streams, rivers, lakes, lagoons, ponds, etc).


Session 9 

Topic: Macrophytes in flowing waters

Chair: Lisbeth Henriksen Co-chair: Trine Just

Short description: Aquatic plant communities are strongly influenced by physical processes, particularly in flowing waters. On the other hand, stream vegetation enhance lowland stream biodiversity and ecolocal function. The purpose of this session is to discuss the factors and feedbacks that influence aquatic plant diversity, community composition, abundance and function in freshwaters with particular emphasis on river flow regimes, influence of riparian vegetation and stream management.


Session 10

Topic: Other topics.

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