Hydroscape:connectivity x stressor interactions in freshwater habitats

All types of ecosystems exhibit connectivity at some level. However, connectivity is the quintessential property of aquatic systems. Connectivity matters in freshwaters because it is the means by which energy, materials, organisms and genetic resources move within and between hydrological units of the landscape (the 'hydroscape'). Hydrological connectivity is a particularly effective vector for multiple climatic, biological, chemical and physical stressors, although other forms of connectivity also link freshwater ecosystems. Our proposal addresses the fundamental question of how connectivity and stressors interact to determine biodiversity and ecosystem function in freshwaters.

Connectivity is multifaceted. It may be directly evident - water moves downhill or across floodplains, or more subtle - the incorporation of terrestrial organic matter into aquatic food webs. Animals and people naturally gravitate to freshwaters, thus providing additional dispersal vectors that can transport propagules to isolated sites. Connectivity may be passive or active and occurs across scales - from local to global. Freshwater scientists recognise the fundamental role of connectivity in key paradigms such as the river continuum and flood pulse concepts. Land-water connectivity is also the founding principle behind catchment management. In truth, however, a long tradition of focus on individual stressors, sites, taxonomic groups or specific habitats, means we have a highly disjointed view of the most intrinsically interconnected resource on the planet. While the need for an integrated approach to the management of water is universally acknowledged, an understanding of the most fundamental infrastructure of freshwaters is lacking. This is a serious obstacle in meeting critical societal challenges, namely the maintenance of environmental sustainability in the face of multiplying human-induced stresses. Without a better-integrated view of the freshwater landscape we struggle to answer basic questions. These include (i) how do organisms, nutrients and energy naturally move within and between landscapes? (ii) how is this basic template altered by different stressors, singly or in combination? (iii) how has widespread alteration of catchment land cover and of the basic infrastructure of freshwaters that largely drives connectivity, redistributed pressures and moderated their effects? (iv) how should reductions in stressors and changes to connectivity that arenow widely implemented, be prioritised when seeking to restore biodiversity and ecosystem function.

Our primary aims are to (1) determine how connectivity (hydrological, spatial and biological) impacts on freshwater ecosystem structure and function in contrasting landscape types, and (2) use this understanding to forecast how freshwaters nationally will respond to (i) multiple, interacting pressures and (ii) management actions designed to reduce pressures and/or alter connectivity. We will achieve these aims by working at different spatial (landscape v national) and temporal (decadal v centennial) scales and using a combination of complementary traditional and more novel molecular and stable isotope techniques. We will combine existing data sources (e.g. archived sediment cores, biological surveys and the millions of records held in national databases) with dedicated sampling to maximise the cost effectiveness of our work and achieve a cross habitat and ecosystem-wide reach.

Landscape scale thinking has become the new mantra of nature conservation and environmental bodies but the knowledge required to underpin large scale conservation and restoration of the hydroscape is currently lacking. In this regard understanding how biodiversity and ecosystem function respond to the changing connectivity x stressors arena in freshwaters is critical. The outputs of the proposed research will deliver the integrated understanding of the hydroscape that is now urgently required.

Our project bridges the gap between policy/management needs and state-of-the-art scientific research on the impacts of connectivity and multiple stressors on freshwater ecosystems. Outputs will provide the scientific evidence base and regulatory guidance needed to support the future sustainable management of freshwater landscapes at the local, national and international scale.
Our results will be useful to organisations engaged in waterbody restoration, biological conservation, the control of invasive species and diseases of wildlife and humans. At the national scale, these include organisations such as Scottish Natural Heritage, Natural England, Natural Resources Wales, Environment Agency, Scottish Environment Protection Agency, GB Non-Native Species Secretariat (NNSS), water utility companies, Wildlife Trusts, National Trust, Royal Society for the Protection of Birds, Plantlife, Buglife and the Rivers Trusts, all of whom we have long established working relationships with. More locally, organisations such as the Norfolk Ponds Project, Norfolk Biodiversity Information Service, Norfolk Wildlife Trust, Norfolk Biodiversity Information Service, Norfolk Farming & Wildlife Advisory Group, Natural England, Norfolk Rivers Trust, Broads Authority (a project partner), River Glaven Conservation Group (http://www.riverglaven.co.uk/), Cumbria Wildlife Trust, Eden Rivers Trust, Cumbria Biodiversity Data Centre and many other similar organisations will also benefit from a better understanding of the links between connectivity and environmental stressors. In particular, we expect the results of this work to challenge the widely held belief that re-connecting isolated waterbodies and removing obstructions to fish migration are important features of restoration projects. For example, in highly impacted systems, the adverse effect of the spread of invasive species and/or pollution caused by such re-connections may be greater than any benefit provided by links to refugia that can provide biological source material for recolonisation.
At the local level, our research outputs will help water managers improve biodiversity and habitat quality in a sustainable way. This will result in greater amenity value, with local businesses benefitting from more visitors and increased income, and increases in native biodiversity and water quality, which will help meet conservation objectives. Residents, visitors and local schools will gain a better understanding of the links between environmental stressors, connectivity, biodiversity and ecosystem function, especially through their combined impact on ecosystem service provision.
At the UK level, the results will provide environmental and conservation agencies (e.g. EA, SEPA, SNH, NRW, NE, Defra, RSPB) and policy makers with a better understanding of the processes involved in achieving the sustainable management of freshwaters and their catchments. In particular, appreciating that measures aimed at restoring a particular site may be impacted by connectivity across the freshwater landscape.
At an international level, the results are expected to inform the implementation of the 2020 EU Biodiversity Strategy, which aims to "halt the loss of biodiversity and ecosystem services". More specific international beneficiaries are the Directorate General for the Environment (DG Environment) in relation to informing Water Policy (Water Framework Directive) and Biodiversity Policy (Europe 2020). The proposed work on heavy metals pollution links directly to the EU Environmental Quality Standards Directive (2008/105/EC), which has the "aim of ensuring that existing levels of contamination in biota and sediments will not significantly increase....". We are also focusing on trace metals that are currently listed as 'Priority Substances' or 'Priority Hazardous Substances' under the Water Framework Directive.