Monday, 28 October 2013

British lakes - boldly going where no lakes have gone before

Three scientists at CEH, Natural Resources Wales and Queen Mary University London discuss the findings of a collaborative lake ecosystems project:

"British lakes are on a new environmental trajectory. For the last half century scientists and managers have focused on how acidification and eutrophication affect the structure and function of lakes and their ecological quality. Now, as the effects of climate change are increasing in magnitude, it is interacting with other pressures, such as the expansion of non-native invasive species. We are therefore facing a situation where management strategies will need to be revised and restoration targets reconsidered as novel ecosystems emerge."

This was one of the main messages derived from a recent workshop convened at the Centre for Ecology & Hydrology's Lancaster site by CEH and Queen Mary University of London (QMUL).

The purpose was to discuss the outcomes of a NERC-funded project, "Whole lake responses to species invasion mediated by climate change", with colleagues in the regulatory and conservation agencies: Natural Resources Wales, Scottish Natural Heritage, Natural England, the Environment Agency and the Cumbria Freshwater Invasive Non-Native Species Initiative. The research is based on Windermere, England's largest natural lake, where unrivalled long-term records and archives exist. The project builds on more than two decades of research on lakes around the world that have revealed that climate change is affecting a range of lake properties throughout the whole lake ecosystem and that some of the changes will be hard to forecast. More specific information can be found at the Windermere Science website.

The John Lund - the CEH vessel used to carry out the long-term
monitoring on Windermere. Photo: Dr Ian Winfield.

 The project found that climate change has:
  • increased water temperature and prolonged the period of stratification
  • favoured species, such as the roach, from southern latitudes
  • disfavoured species, such as the Arctic charr, from northern latitudes
  • changed the fish community, leading to altered fish diet and food-web linkages
  • altered the zooplankton community structure
  • led to earlier phytoplankton growth in the spring and later growth in the autumn

These findings will directly inform the future management of one of the most important lakes in England. However, there are lessons to be learned as well, as many of the changes are likely to be common across lakes in different regions.

Taking a zooplankton net tow. Photo: Dr Peter Smyntek

There was common agreement at the workshop that our lakes are a critical national resource delivering a range of ecosystem services, but they are under threat. In particular, they are sensitive to invasive species which favour already disturbed environments. The importance of having access to long-term datasets and archived samples was acknowledged but the insights they provide will be strengthened by using other techniques, such as stable isotopes to trace food-webs and by modelling. Other research priorities specific to invasive species included identification of introduction pathways, early detection, likely spatial and temporal impact of specific species, and the effectiveness of biosecurity measures.

Guest blog by Dr Catherine Duigan (Head of the Marine and Freshwater Ecosystems Group, Natural Resources Wales, Bangor, @NatResWales), Prof Stephen Maberly (Head of the Lake Ecosystems Group at CEH), and Dr Jonathan Grey (Reader in Aquatic Ecology, QMUL).

Additional information

Windermere Science

Lake Ecosystems Group at CEH

Friday, 25 October 2013

The Harlequin ladybird, Harmonia axyridis: time for global collaboration

International cooperation is very important in preventing and controlling the spread of invasive species globally, as Helen Roy and Peter Brown of the UK Ladybird Survey explain in a guest blog:

It is almost ten years since the Harlequin ladybird, Harmonia axyridis, was first recorded in the UK. This invasive alien species is native to Asia and so it is particularly poignant for us to have been invited to speak at the International Congress on Biological Invasions hosted at Qingdao*, China.

We're taking part in a session entitled "Harmonia axyridis: time for global collaboration" and feel privileged to be here representing the UK Ladybird Survey, alongside the Centre for Ecology & Hydrology and Anglia Ruskin University. During our time in China we are presenting research spanning predator-prey and natural enemy interactions through to host plant and habitat associations. All possible because of the records collated by the UK Ladybird Survey.

The online UK Ladybird Survey (including the Harlequin Ladybird Survey) was launched in 2005 following the arrival of the harlequin ladybird in the UK. We could not have imagined the response - tens of thousands of people from across the UK have contributed records of the harlequin ladybird and native species of ladybird. These observations have been invaluable in providing a unique insight into the ecology of this invader and the effects it is having on native species.

Harlequin ladybird. Photo: Barnaby Smith

The threat posed by invasive alien species is widely recognised and the harlequin ladybird provides a model system for exploring invasion biology making the data collected through the UK Ladybird Survey extremely valuable . The success of the online survey has also provided the inspiration for the development of a system for reporting many other alien species in Britain. 

One aim of our visit to China is to strengthen collaborations with researchers from around the world, and in particular to forge links with scientists working here. We hope to build on our understanding of how the ecology of the harlequin ladybird differs in its native and invaded ranges.

The harlequin ladybird is a dominant species in China as it is within the invaded range. Today we had the opportunity to observe, with excitement, the harlequin ladybird on the seafront trees of Qingdao. It was a fitting conclusion to a very productive and worthwhile trip.

Helen and Peter recording the harlequin ladybird
in Qingdao, China.

Helen Roy (Centre for Ecology & Hydrology and volunteer scheme organiser for the UK Ladybird Survey)

Peter Brown (Anglia Ruskin University and volunteer scheme organiser for the UK Ladybird Survey)

Additional information

UK Ladybird Survey

Staff page of Dr Helen Roy, CEH

Staff page of Dr Peter Brown, Anglia Ruskin University

International Congress on Biological Invasions 

Great Britain non-native species secretariat

* Random fact - Qingdao city was host of the 2008 Olympic sailing competition

Thursday, 24 October 2013

Biodiversity indicators and the Biological Records Centre

The 2013 update to the UK Biodiversity Indicators has just been published on the JNCC website.
CEH scientists working within the Biological Records Centre contribute to several of the indicators, building on our wealth of knowledge and links to most of the UK's wildlife recording schemes. In particular, for 2013, our scientists have contributed to development of the new index on the status of priority species (C4a).

Dr Nick Isaac of CEH explains more:

"The new indicator C4a uses data from national surveys, such as the UK Butterfly Monitoring Scheme. The index provides an annual summary of the abundance of 210 mammal, bird, butterfly and moth species, all of which have been identified as priorities for the four national conservation agencies. This property makes this index much more sensitive than the old C4, in which species were categorised as declining, stable or increasing based on expert opinion."

"In addition, we also produced a supplementary index based on distribution data. These 'biological records' are not collected in a standardised way, which makes the data extremely noisy and liable to produce biased estimates of species trends. Within the Biological Records Centre, we've invested heavily in trying to understand this bias, and to extract a meaningful signal of change from the noise in the data. This investment has now paid off, because we're now able to report on the status of  taxonomic groups, such as bees, that lack standardised monitoring schemes."

"Both the abundance and distribution-based indicators show a decline of 50-60% since 1970, reinforcing the message that conservation agencies have their work cut out to prevent more species from going extinct."

More details of the C4a indicator can be found in the technical report, "Status of threatened species - status of priority species".

Other UK biodiversity indicators with CEH involvement include:

  • C6. Insects of the wider countryside (butterflies) population (data from CEH's joint stewardship of the UK Butterfly Monitoring Scheme with Butterfly Conservation)
  • C2. Habitat Connectivity (Countryside Survey data)
  • B6. Pressure from Invasive species (reflecting our work with the National Biodiversity Network)
  • B5. Pressure from Pollution
  • C7. Plants of the wider countryside (data from CEH's Countryside Survey)

CEH science also played a key role in the 2011 National Ecosystem Assessment, which is the basis of Indicator D2. Biodiversity and ecosystem services (terrestrial).

Additional information

Biological Records Centre

Staff page of Dr Nick Isaac, CEH

Tuesday, 22 October 2013

National hydrometric data - what does the future bring for the UK's NRFA?

In two previous blog posts this month, we explored how the hydrometric data held by the National River Flow Archive and the National Groundwater Level Archive have been used in past and present scientific research, and how such a valuable data resource is vital for taking a long view of both hydrological trends and significant one-off events. Our series has coincided with a special meeting, on Tuesday 22 October 2013, to celebrate 30 years of the NRFA being hosted at CEH's Wallingford site. To conclude the series, Jamie Hannaford, head of the National River Flow Archive, looks to the future and at what the next few years might bring...

The past 30 years have seen incredible change in how we do our jobs, most obviously in the technology used to gather and disseminate hydrometric data. The next 30 years will undoubtedly see huge change again. When you think about it, 30 years is a generational timescale, it's a career span, it's a period that can expect to see life-changing developments. Hydrometric data and analysis is already important to society for underpinning effective water management, but it will assume even greater importance in global water management over the next 30 years, thanks to the challenges of population growth and movement, land use change and of climate change leading to an intensification of the hydrological cycle.

The NRFA, as the UK's national hydrometric information service, will be crucial to meeting these challenges, lying as it does at the heart of the hydrometric information lifecycle and managing as it does a long-term archive that will be able to take an ever longer view of events such as the 2010-2012 drought to flood transformation. Reliable, easily accessible, contextualised data and analysis will play a key role as scientists and water practitioners meet the world's water resource management needs.

The NRFA already provides its data and analysis in many formats

From the original print publications the NRFA delivered in the 1980s, to the digital outputs it now provides, our data is already, and will continue to be, served in many formats, but our fundamental maxim will always be to turn the data into valuable information. We always make sure we know where the data is coming from, so we can guide our end users.

The technological landscape will certainly continue to develop. Will we be a nation of armchair hydrologists by 2043? In some respects, thanks to remote sensing and satellite capabilities, it's possible to some extent now. But as well as opportunities, technology brings its own challenges - both in the huge amount of data that can be gathered and in the interpretation and validation of that data. For all the hydrometric data that can be gathered, we still need to understand what it is telling us. And we still need our monitoring partners to collect data first-hand to complement the models and the satellite technology.

The provision of reliable hydrometric data in the 21st century will be
crucial for global water management

Future developments

An important area for the NRFA now is to look at how to integrate our river flow data with other types of monitoring, for example near real-time soil moisture data, citizen science initiatives etc, to build up a fuller environmental picture. Our role will be to bring these other types of information together with the river flows; to help with interpreting and understanding them in context with other environmental variables.

Currently we are reviewing our hydrological summaries and looking at different options for enhancement, for example using the best modelling capabilities from CEH and other organisations to deliver improved outlooks and better drought indicators. We are working more closely than ever with international colleagues in organisations such as the US National Drought Mitigation Center and CSIRO in Australia, and aim to improve the information that we and other national hydrometric data providers can supply. It is a challenging task to undertake when hydrometric networks are under pressure worldwide, along with the resources for long-term monitoring.

In the shorter term, you can expect the NRFA to offer daily catchment rainfall on its website from next year. We will also be taking on the validation for HiFlows-UK, the UK's principal source of flood peak data, and making this available from our website in the near future.

Who can really say what the NRFA in 2043 will look like? The last 30 years have been a tremendous effort of stewardship, and the next 30 years will be also, but we are ready and able for the challenge, thanks to the support of our partners. Our data and analysis has informed the likes of the Pitt Review on flooding, which followed the 2007 summer floods, as well as the National Ecosystem Assessment and the IPCC's recent 2013 climate change assessment. We will continue to give that much needed national, strategic assessment that is crucial for water management in this country.

Jamie Hannaford

Additional reading

Dixon, H, Hannaford, J and Fry, M J, 2013, The effective management of national hydrometric data: experiences from the United Kingdom. Hydrological Sciences Journal.

The 2010-2012 drought and subsequent extensive flooding - a remarkable hydrological transformation by Terry Marsh, Simon Parry, Mike Kendon & Jamie Hannaford. 2013. PDF [7.05mb]

Hydrometric data - the long view (first in our special blog series on the NRFA and hydrometric data)

An unprecedented hydrological transformation (second in our blog series)

View photos from the NRFA 30th anniversary event on Flickr

Related links

National River Flow Archive

Staff page of Jamie Hannaford, CEH

CEH makes a Big Bang at Cumbria science fair

Staff and students from CEH's Lancaster site shared their enthusiasm for all living things at the South Cumbria Big Bang science fair earlier this month. Their stall, entitled "Slimy Science Creature Challenge", encouraged primary and secondary students to get their hands dirty and think about what it means to work in ecology:

Five staff and students from our Lancaster site introduced young students to the science of ecology at the South Cumbria Big Bang Fair, held in Furness College, Barrow-in-Furness from 15-16 October 2013.

The stall included a "Slimy science creature challenge", where 50 magnets depicting organisms from diatoms to wolves were hidden in a large bucket of green slime (created using Gelli Baff, which consists of the stuff used as an absorbant in disposable nappies). The (highly competitive!) student contestants had a limited time to extract as many creatures from the goo using only one hand, then only a minute to decide to which level of the food chain their organisms belonged - not as easy as it sounds! All contestants were rewarded for their efforts with a sweet treat, and the top scorer from each session went away with a mini microscope to help them hone their ecological skills at home.

Secondary students from around the south Cumbria region visited on Tuesday, whilst on Wednesday it was the turn of the primary school students. Much fun was had by all and, judging by the results, there are some very capable young people who are willing to get their hands dirty! It wasn't all goo and slime though, as the contents of a compost bin (and the associated flora and fauna) were available for students to examine using a microscope. Meanwhile, CEH staff were on hand with leaflets and magazines explaining the roles of ecologists and hydrologists, and how enjoyable environmental science can be as a career choice.

The Cumbria Big Bang Fair was organised by STEM Cumbria and was visited by more than 400 students each day from all over the region. It was host to a plethora of different businesses, educational institutions and enterprises that use STEM (Science, Technology, Engineering and Maths) on a day to day basis.

Our Lancaster-based staff plan to take part again next year to help inspire the next generation of budding environmental scientists.

Beth Penrose, Jacky Chaplow, Claudia Moeckel, Elaine Potter and Andy Sier

Additional links

Cumbria STEM Ltd

Thursday, 10 October 2013

An unprecedented hydrological transformation

A huge number of scientific papers have delved into the extraordinary data held by the National River Flow Archive and National Groundwater Level Archive. As our blog series on hydrometric data continues, Simon Parry of CEH (right) discusses one of the most recent papers to use the data, newly published in the Weather journal, which analyses the dramatic transformation from drought to flood in the UK during the summer of 2012.

Whilst this year's fine and dry summer was very much welcome, it was not typical of the more unsettled summers of the last few years. Although the Olympic and Paralympic Games in 2012 were spared the worst of the weather, from April 2012 onwards a succession of wet fronts drenched the UK, in particular England & Wales, resulting in the wettest year for more than a century.

This episode emphatically put to an end concerns about the water resources situation, which saw hosepipe bans implemented in April across south, central and eastern England affecting 20 million consumers. Recent research by CEH scientists, in collaboration with the UK Met Office, published last month in Weather, finds that the transformation from drought to floods in England & Wales is without modern parallel in the historical record (Parry et al. 2013).

The extreme drought of 1975-76 remains the most severe in the historical record, most likely the worst experienced in the UK for at least the last 250 years (Rodda & Marsh 2011). This episode was terminated dramatically in September and October 1976, over which time England & Wales received almost double the long-term average rainfall.

The 2010-12 drought did not reach the same intensity as 1975-76 (Kendon et al. 2013); the summers were not hot or particularly dry in 2010-12, in contrast with heatwave-dominated droughts in 1976 and 2003. However, the rainfall shortages were concentrated in the winter half-years (October-March), a vital time for the recovery of water resources and, as such, outflows from England & Wales in March 2012 were lower than the corresponding point in 1976. Hosepipe bans were implemented in several areas at the end of the normal groundwater recharge season (April); there was little prospect of improvement in the water resources situation, barring something extraordinary happening...

Something extraordinary did happen. Whilst the transformation in 2012 may not have been as spectacular in rainfall terms as that of 1976, England & Wales recorded new record rainfall (series from 1766; Alexander & Jones 2001) for April, June and the summer half-year (April-September), and April-December 2012 was the wettest of any nine-month period in ~250 years.

Flood damage in England, December 2012. Photo: Heather Lowther

Groundwater recharge through the summer half-year

The most important impact of the succession of rain-bearing frontal systems was to re-wet soils which allowed the replenishment of groundwater to resume. What made the transformation in 2012 particularly unprecedented was the resumption of groundwater recharge through the summer half-year; the patterns of hydrological response tracked in the opposite direction to normal seasonal conditions.

Perhaps owing to the British preoccupation with the weather, much attention is given to rainfall figures in characterising the water situation in this country. However, water resources are more complex than this; the relationship between rainfall and runoff is not one-to-one, owing to catchment characteristics and antecedent conditions.

The distinction between a transformation in rainfall and the unprecedented hydrological transformation is an important one; the former would not necessarily have terminated hydrological drought conditions, but the latter did so emphatically. If there had been no concurrent response in groundwater levels following the rainfall, it is likely that hosepipe bans would have remained in place even through a moderately wet summer. This would have been a difficult message for the water companies to communicate to the public, so perhaps the industry was happy on more than one level to have witnessed a hydrological transformation without modern parallel.

Simon Parry

Simon Parry is a hydrologist based at the Centre for Ecology & Hydrology's Wallingford site.



Alexander, L V, and Jones, P D (2001) Updated precipitation series for the UK and discussion of recent extremes. Atmospheric Science Letters, 1, 142-150.

Kendon, M, Marsh, T and Parry, S (2013) The 2010-2012 drought in England and Wales. Weather, 68 (4), 88-95.

Parry, S, Marsh, T and Kendon, M (2013) 2012: from drought to floods in England and Wales. Weather, 68 (10), 268-274.

Rodda, J C and Marsh, T J (2011) The 1975-76 drought - a contemporary and retrospective review, Centre for Ecology & Hydrology. 58pp. [PDF, 13mb]

Additional information

A comprehensive report by Terry Marsh, Simon Parry and Jamie Hannaford, in collaboration with Mike Kendon (Met Office), on the 2010-12 drought and subsequent hydrological transformation will be published later this month and will be available to download freely from the CEH website.

Next in our hydrometric data blog series, Looking forward - where the archives are going next... Watch this space!

Related links

CEH Blog: Hydrometric data - the long view

National River Flow Archive  

Thursday, 3 October 2013

Hydrometric data: The Long View

Each week BBC Radio 4's The Long View uses a variety of expert witnesses to examine stories from history that resonate in today's headlines.

Later this month, CEH will host more than 100 distinguished hydrologists who will spend a day taking the 'long view' of the data collection and research work of the UK's National River Flow Archive (NRFA) and National Groundwater Level Archive (NGLA), both of which have been hosted at our Wallingford site since the early 1980s, but which contain records dating back to the first half of the 19th century.

Wendover Springs - thought to be the earliest extant stream flow monitoring
site in the UK. 

The 30th anniversary celebration of the Wallingford move, to be held on 22 October 2013, will review the achievements of the archives and the exploitation of this rich hydrological data resource by a broad user community, which includes regulators such as the Environment Agency, water companies, academic scientists, and environmental and engineering consultancies. The data has also made its way into several scientific papers referred to in the recent IPCC WG1 assessment.

In addition to river flow and groundwater level data, rainfall records and reservoir levels are also held in the archives and the incredible dataset has allowed CEH and BGS scientists to produce a variety of key publications examining both hydrological trends – for example, Are UK floods getting larger? – and the significance of one-off events, such as the 1976 drought. Comparisons between the latest data and the historic record also provide the backbone of the UK's monthly hydrological summary.

Whilst delving through the archives in preparation for this post, I came across this fascinating history of hydrological monitoring before 1985 [PDF], which details how, although Britain has a three centuries-long history of rainfall recording, river flow monitoring only became 'fashionable' after the second world war as industry and government increased their demand for water. The work to establish a national river flow gauging network in the 1950s and 1960s built on a small number of sites that had been established over the previous century, including Wendover Springs in Buckinghamshire - thought to be the earliest extant stream flow monitoring site in the UK.

On the day itself, presenters will look back at how hydrometric monitoring developed in the UK, in response to factors such as the perceived increase in water requirements. They will also examine some of the latest techniques for both monitoring the UK's water cycle, investigate how monitoring and the archive might develop in the future, and tackle the difficult question of what data should we be archiving nationally, given the resource constraints imposed by the current financial situation. In summary, they will take a 'Long View' of a data archive from one of the UK's major environmental monitoring networks, an archive which is particularly important because the UK climate is inherently variable, so short-term tendencies may well not be indicative of long-term trends.

Barnaby Smith

CEH website: Images of gauging stations which have provided some of the oldest records in the archive

Flickr: Album of historic images from the Pynlimon catchments

Additional information

Over the next couple of weeks we will be blogging in more detail about some of the material being presented at the meeting. Further details of the meeting can be found here. Registration is now closed but we will be making much of the content available from this blog and the NRFA pages on the CEH website.

If you're interested in learning more, take a look at the NRFA web pages, where you can find reams of information on how monitoring takes place and how the data is used, and you can also download data for more than 400 of the UK's river flow gauging sites. Information about the records and details of scientific papers which have used the records can be found on the NRFA publications pages.