Looking forward through the past: identification of 50 priority research questions in palaeoecology

1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date, there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on time-scales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation and novel ecosystems; biodiversity over long time-scales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes and the continued application of long-term data for better-informed landscape management

Critical loads of nitrogen and their exceedance in UK freshwaters

In June 1994 the United Kingdom government signed the European sulphur protocol which committed them to a 70% reduction in SO2 emissions by the year 2005 and 80% by 2010, based on 1980 levels. This was the first instance of international legislation being formulated using the critical load concept. Notwithstanding the anticipated benefits to the environment of such reductions it was also recognised that such improvements could be diminished unless a similar approach was used to address the problem of increasing nitrogen emissions. The Freshwater Sub-group of the UK Critical Loads Advisory Group (CLAG) has responsibility for evaluating available techniques for calculating critical loads for nitrogen and for establishing a scientific programme to address key issues and gaps in our knowledge of nitrogen dynamics. This paper summarises the preliminary findings of the Freshwater Group with respect to the nitrogen status and critical loads of UK freshwater

River and lake water quality: future trends

It is now accepted that some human-induced climate change is unavoidable. Potential impacts on water supply have received much attention, but relatively little is known about the likely impacts on water quality. Projected changes in air temperature and rainfall will affect river flows and, hence, the mobility and dilution of nutrients and contaminants. Increased water temperatures will affect chemical reaction kinetics, lake stratification, in stream process and freshwater ecological status. With increased flows there will be changes in stream power, water depths, water velocity and sediment loads. These will alter the morphology of rivers and the transfer of sediments to lakes, thereby impacting water quality and freshwater habitats in both lake and stream systems. This paper reviews the potential impacts of climate change on rivers and lakes in the UK. Widely accepted climate change scenarios suggest more frequent droughts in summer, as well as flash-flooding, leading to uncontrolled discharges from urban areas to receiving water courses and lakes. Invasion by alien species is highly likely, as is migration of species within the UK adapting to changing temperatures and flow regimes. Lower flows and reduced velocities result in higher river and lake water residence times, which will enhance the potential for algal and cyanobacterial blooms and reduce dissolved oxygen levels. Upland streams and lakes could experience altered acidification status, as well as increased dissolved organic carbon and turbidity, requiring action at water treatment plants to prevent toxic by-products entering public water supplies. Storms that terminate drought periods will flush nutrients from urban and rural areas and may cause acid pulses in acidified upland catchments. Tables 1 and 2 provide concise summaries of the expected impacts of climate change on future river and lake water quality