New Zealand 2018

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Themes & sessions

Theme: Biodiversity, conservation and bio-monitoring

  1. Genetic diversity in aquatic plants Chair: Prof Ludwig Triest
  2. Threats to aquatic plant biodiversity Chair: Dr Tobias Bickel
  3. Conservation of aquatic and wetland vegetation Chair: Paul Champion and Richard Lansdown
  4. Assessment and ecological condition Chair: Prof Teresa Ferreira

Theme: Management and invasive plants

  1. Biology, impacts and risk assessments Chair: Dr Andreas Hussner
  2. Aquatic nuisance plant monitoring techniques, surveillance and detection Chair: Dr John D. Madsen
  3. Improving control methods of invasive plants Chair: Prof Rob Richardson
  4. Eradication case studies and strategies Chair: Dr Tony Dugdale

Theme: Ecosystem response and restoration

  1. Stress ecology in the context of variable resource availability Chair: Prof Elisabeth Gross
  2. Environmental change – climate change Chair: Dr Liesbeth Bakker
  3. Macrophytes in flowing waters Chair: Dr Fleur Matheson and Assoc Prof Tenna Riis
  4. Biotic interactions and ecological thresholds Chair: Dr Sabine Hilt
  5. Restoration and resilience of aquatic ecosystems Chair: Assoc Prof Julie Coetzee

ThemeBiodiversity, conservation and bio-monitoring

Genetic diversity in aquatic plants

Chair: Prof Ludwig Triest

Molecular tools are becoming increasingly important in ecology, allowing us to understand the diversity present in aquatic plants. In aquatic populations, molecular ecology can be used to identify species or hybrids, to understand their survival strategies that can be mixed (sexual/clonal) and their dispersal ecology. Habitat modifications can disrupt gene flow and alter genetic connectivity of aquatic plant populations through isolation-by-distance, as well as changing their local structure.

This session aims to compile work on how genetic information of populations can be used in aquatic plant ecology to better understand their life strategies, survival and dispersal ecology for practically aiding the management of aquatic plant vegetation. Focus will be on the relevance and applications, not on the molecular methods as such.

Genetic diversity in aquatic plants (continental and coastal habitats)

  • Species and hybrid identification (phylogenetics and barcoding)
  • Large-scale patterns (phylogeography, long-distance dispersal)
  • Gene flow (pollen flow and seed flow), isolation-by-distance
  • Survival strategies (sexual, clonal, mixed) and fine-scaled structures
  • Movement ecology, spread and dispersal patterns

Threats to aquatic plant biodiversity

Chair: Dr Tobias Bickel

There are multiple threats to aquatic plant biodiversity which are invariably linked to human activities. These include global scale anthropogenic impacts (e.g. climate change and invasive species), catchment scale modifications (e.g. altered nutrient regimes due to land use changes) and local disturbances (for example inappropriate water body management). Together, these factors directly or indirectly reduce aquatic plant diversity. While a better picture about the threats to aquatic plant diversity is currently emerging, we still have little understanding of how to best ameliorate or mitigate these impacts to reduce future biodiversity losses.

This session will focus on:

  1. Gaining a deeper understanding of the actual processes that cause a decline in aquatic plant diversity
  2. Finding ways to mitigate impacts and stop further species erosion.

Conservation of aquatic and wetland vegetation

Chair: Paul Champion and Richard Lansdown

Globally, freshwater systems cover less than 1% of the Earth’s surface, yet they provide a home for nearly 10% of described plant and animal species. Various national and global assessments of conservation status show a disproportionate number of threatened species including plants occur in freshwater habitats, perhaps not surprising given the threats discussed in the previous session. The key to management of threatened species is gaining an understanding of their autecology and manipulating their environment to favour their continued survival.

This session will focus on:

  1. Cataloguing the threatened status of wetland and aquatic plants on a range of spatial scales
  2. Discussion of successful and unsuccessful attempts at threatened plant conservation management
  3. Identify key requirements for successful species recovery plans

Assessment and ecological condition

Chair: Prof Teresa Ferreira

The idea that aquatic plants can indicate changes in water quality is informed by decades of research and has been used for conducting or evaluating the effects of eutrophication, both locally or at the basin scale, using composition or traits. Riparian vegetation and emergent plants are good indicators of changes in hydromorphology and flow regime. Plant assessment of ecological conditions is effective in lakes and rivers, but also in coastal and transitional waters, and presently many vegetation indices are applied under legislative frameworks, aiming to detect different pressures.

In this session we will deal with the results of ongoing bioindication programs, their efficacy to show changes and uncertainty estimations, and with novel plant indicators able to complement or improve those in place.

ThemeManagement and invasive plants

Biology, impacts and risk assessments

Chair: Dr Andreas Hussner

Aquatic plants play a substantial role in the functioning of aquatic ecosystems. But some plants show invasive behaviour and cause serious economic and ecological impacts. Based on species biology and documented impacts, pest risk assessments are carried out to identify invasive or potentially invasive aquatic plant species.

For this session, all abstracts on plant biology (especially those highlighting attributes of invasive plants), impacts of invasive aquatic plants and risk assessments of invasive and potentially invasive aquatic plants are welcome.

Aquatic nuisance plant monitoring techniques, surveillance and detection

Chair: Dr John D. Madsen

The purpose of this session is to discuss the best techniques, both quantitative and qualitative, to find and assess populations of nuisance plants, and evaluate them for potential management, plan an appropriate management approach, and later evaluate the effectiveness of implemented management on the control of nuisance species and collateral impact on non-target native populations. Techniques would include qualitative assessment, frequency surveys, assessments of abundance and distribution, including both direct and remote surveillance techniques. Relevant methods could include, but not be limited to, visual surveys, citizen science, line or point intercept surveys, biomass sampling, hydro-acoustic sampling, drone, aerial, and satellite remote sensing.

The session aims to exchange ideas on how best to find nuisance or invasive plant populations, assess the size of the infestation for management, and evaluate the success of management programs.

Improving control methods of invasive plants

Chair: Prof Rob Richardson

Management of invasive aquatic plants is often a balancing act of determining techniques that can reduce populations of the invasive species while limiting impacts on non-target species. Specific management techniques may be acceptable in some situations, but not acceptable under other conditions. This often limits the implementation of management techniques across broad areas. Improving control methods can lead to greater economic savings, environmental protection, and increased public approval for the implementation of management programs.

This session welcomes data driven presentations which evaluate any systemic improvement to invasive aquatic management techniques and strategies. Control methods of all types are welcomed.

Eradication case studies and strategies

Chair: Dr Tony Dugdale

Eradication of invasive weeds is a cost effective long term management method, because, if successful the need for ongoing management is eliminated. Although this benefit is real, successful eradication is difficult and costly to achieve, because it relies on extirpation of every plant and propagule. This can be particularly difficult in aquatic situations, where the ability to detect and control aquatic weeds, in an early stage of invasion, is limited by the aquatic environment.

This session seeks to reveal examples of successful and unsuccessful aquatic weed eradication attempts, to allow key features of success (stage of invasion, detection techniques and strategies, management decisions, weed characteristics, landscape, hydrology, control tools, etc.) to be explored.

ThemeEcosystem response and restoration

Stress ecology in the context of variable resource availability

Chair: Prof Elisabeth Gross

Aquatic plants face multiple challenges - potential stressors such as pollutants (eutrophication, metals, pesticides), or changes in water level and temperature - and might react in a species-specific or functional group specific ways towards these constraints.

This session welcomes contributions that look at the effects of single or multiple stressors on aquatic plants, with a special focus on plant traits, plant stoichiometry or ecotoxicology.

Environmental change – climate change

Chair: Dr Liesbeth Bakker

Aquatic systems are increasingly subject to climatic and environmental changes – mostly due to anthropogenic influences. These affect the growth, species traits, abundance, community composition, diversity and stability of macrophyte vegetation. In turn, this may alter the ecosystem functions of macrophytes, such as nutrient and carbon cycling, the role of macrophytes in the food-web, and their role in regime shifts and more.

In this session we present the state-of-the-art of research on climate and environmental change on macrophytes. This includes alterations in hydrology and water level, and the more recent climate change impacts, such as temperature rise and the increasing abundance of exotic species.

Macrophytes in flowing waters

Chair: Dr Fleur Matheson and Assoc Prof Tenna Riis

Aquatic plant communities are strongly influenced by physical processes, particularly in flowing waters.

The purpose of this session is to discuss the factors and feedbacks that influence aquatic plant diversity, community composition and abundance in freshwaters with particular emphasis on river flow regimes and the influence of riparian vegetation.

Biotic interactions and ecological thresholds

Chair: Dr Sabine Hilt

Macrophytes are involved in biotic interactions with all aquatic organism groups. Examples range from small, often overlooked organisms such as plant pathogens and arbuscular mycorrhiza up to the more obvious herbivorous fish, waterfowl or mammals. These biotic interactions can be neutral, however, often they have direct and/or indirect negative or positive consequences for macrophyte development and thus potentially water quality. A well-known example is regime shift in shallow lakes that can be provoked by perturbations of the biotic interactions between macrophytes and fish, invertebrate grazers, phytoplankton and periphyton. While qualitatively relatively well understood, we still lack a lot of quantitative knowledge about these interactions which prevents both, predicting threshold levels for ecosystem transitions as well as their successful application in lake management. In addition, macrophyte-centered interactions may also have similar consequences in other aquatic ecosystems.

In this session, we welcome contributions that unravel both known and new mechanisms of biotic interactions between macrophytes and other biota (excluding direct human activities such as mowing) at all spatial and temporal scales. We welcome both fundamental and applied studies on biotic interactions leading to intended and unintended changes in macrophyte performance up to complete ecosystem transitions.

Restoration and resilience of aquatic ecosystems

Chair: Assoc Prof Julie Coetzee

Ecological resilience, the resistance of an ecosystem to change, particularly from one stable state into another, is an important consideration in the management of aquatic ecosystems, as high resilience of a restored ecosystem lowers the risk of a shift back into a degraded state. The perception that many ecosystems respond smoothly to environmental change is not necessarily true, and recent studies documenting alternate stable states suggest that future management should focus on facilitating ecological resilience because this reduces the risk of stable state shifts.

In this session, we would like to focus on theory and examples of restoration and resilience in freshwater aquatic ecosystems, including effectiveness of restoration methods, bio-manipulation and the re-establishment of vegetation.