Sharing freshwater insights at the 2023 Cumbrian Lakes Research Forum

A rainy Wednesday in November 2023 marked our eighth annual Cumbrian Lakes Research Forum bringing together freshwater experts from research, government agencies, charities and businesses working in and around the Cumbrian Lakes. This year’s event was the first hybrid iteration and we welcomed 20 online attendees as well as 30 in-person at UKCEH Lancaster. Heather Moorhouse summarises the discussions…

This year’s Cumbrian Lakes Research Forum focused on water quality, quantity, access, and freshwater biodiversity, with examples from both the Lake District and further afield, highlighting wide relevance of freshwater research and the importance of cross-catchment and interdisciplinary dialogue.

Flood histories

Our first presenter was Daniel Schillereff from King’s College London who spoke about reconstructing the flood histories of Cumbrian Lakes using sediment cores from Brotherswater, Ullswater, Bassenthwaite Lake and Buttermere. He described how building a picture of flood histories can help us to understand flood-rich versus flood-poor periods in time and how historical trends can help predict future flood trajectories.

By measuring lake sediment characteristics such as grain size, geochemical composition, and radioactive isotopes, Daniel and his team determined flood records over centennial timescales. They found a relationship between the North Atlantic Oscillation and winter floods, and that landscape modification has increased the vulnerability of Cumbrian catchments to flood hazards. The importance of site-selection and understanding the processes of sediment delivery were key recommendations from his experience (see Convergent human and climate forcing of late-Holocene flooding in Northwest England).  

Phosphorus histories

Continuing to fly the flag for palaeolimnology, second speaker Madeleine Moyle from the University of Liverpool described her work with John Boyle on reconstructing phosphorus (P) histories. Much like flood histories, long-term P records are rare. P is often the limiting nutrient for algal growth not just in Cumbrian lakes but many freshwaters - even small inputs can change a lake’s ecology, with many lowland lakes experiencing nutrient enrichment from human activity (see Towards a history of Holocene P dynamics for the Northern Hemisphere).

Madeleine and John’s work has focused on using P recorded in the sediments as well as models to infer in-lake and catchment P inputs to assess and help improve appropriate current in-lake total P targets. A synthesis of records from the northern hemisphere showed the centennial scale influence of human induced land-use change and why in the present-day context of climate change and socio-cultural factors, historical baselines may not be the most meaningful targets for restoration. Using sediment records can help provide the catchment context and feed into discussions that ensure realistic targets to address present-day disruption of ecosystem functioning.

Restoration

The next speaker was Melanie Fletcher, Senior Specialist in Standing Waters at Natural England. Melanie emphasised the need for collective working for large-scale restoration, and presented the nature of shoreline disturbance at Bassenthwaite Lake, identified, and mapped using a walkover survey in collaboration with UKCEH. Shoreline pressures ranged from hard engineering eg. road infrastructure or recreational access to grazing pressure, poor drainage, and shoreline vegetation disturbance.

To start to address these pressures, Natural England, the Lake District National Park Authority, West Cumbria Rivers Trust, and fantastic volunteers worked on a range of restoration techniques mimicking natural processes and engaging with visitors to the site about the work. The techniques included willow staking, fixing willow pegs into the ground to stabilise eroding banks. Sadly, some of these were subsequently removed, highlighting the importance of ongoing community advocacy and support in restoration.

Addressing knowledge gaps

A discussion session followed, centred on addressing scientific knowledge gaps to help improve freshwater management. A key issue is how to better apportion and quantify the multiple sources of P in lake catchments such as Windermere. Sources range from the diffuse to point, from septic tanks to forestry, agricultural and wastewater operations. The level of regulation of these sources varies, as does maintenance and operational practice. Coupled with a lack of resourcing for monitoring, this makes it difficult to determine accurately where, when and how P is getting into our freshwaters.

Ultimately, climate change will likely dominate, modify, and interact with other stressors - as scientists we need to be able to keep up with these changing baselines and trajectories. Robust monitoring and empirical evidence was therefore noted as paramount to not only address these scientific knowledge gaps but also translate them into action.

Lynsey Harper from the Freshwater Biological Association (FBA) kicked off the afternoon session with an overview of the Love Windermere Partnership and its Data, Science and Evidence workstream objectives. These include the Windermere Integrated Science Plan, producing State of Windermere reports, and seeking long-term funds to support and promote robust science.

One scientific programme partly run by the FBA in conjunction with Lancaster University is The Big Windermere Survey. This survey has achieved the broadest spatial coverage of Windermere sampling in a single day and has engaged with over 450 volunteers. The four surveys conducted so far have targeted each season, meaning that an annual overview of conditions is now possible. Broadly, summer and autumn sampling events recorded a higher proportion of sites with high nutrient levels and faecal indicators. This large spatial survey, which has enabled the detection of hotspots of poor water quality, has been funded for another two surveys in November ‘23 and February ‘24.

Reservoirs

Reservoirs were the next subject of discussion, with Alex Elliott from UKCEH presenting his work modelling the effects of reservoir drawdown on phytoplankton community composition. Whilst based on reservoirs in the Thames catchment, this work provides important learnings for reservoirs elsewhere, including those in the Lake District such as Thirlmere.

Modelling revealed a difference in phytoplankton community change between drawdown in shallow and deep reservoirs, with deep reservoirs often being drawn down to a greater extent, leading to problematic changes in phytoplankton communities. These changes involved the greater abundance of small centric phytoplankton which can penetrate water filters and require costly end- of-pipe treatment. Ultimately, these results indicate that from a water company perspective, deep reservoirs whilst less productive when water levels are high, may be more vulnerable to water level changes than previously thought and require more considered management across the reservoir network.

Nitrogen impacts

Next on the agenda came two talks on the nutrient nitrogen (N). The first, presented by UKCEH’s Don Monteith, covered the impacts of N on upland waters using monitoring from the UK Upland Waters Monitoring Network (UWMN), an incredible 35-year dataset. These upland waters show recovery from acidification thanks to transnational agreements that have dramatically reduced sulphur dioxide emissions.

Interestingly, whilst N oxide emissions have also reduced since 1990 it has not been to the same extent as sulphur dioxide. Algal growth in upland waters are typically co-limited by N and P, with inputs of organic-N causing changes to upland water ecology. For example, the UWMN has recorded an increase in the macrophyte Juncus bulbosus, a species indicative of N-enriched conditions. The complex nature of N-cycling and leaching from both soils and aquatic systems, coupled with atmospheric deposition make quantifying these sources and therefore, feeding into emissions solutions, difficult.

Next, Imke Grefe from Lancaster University, presented her work on the N-biogeochemistry of stream-lake networks of the Lake District. Imke has compared the different processes between upland and lowland networks to disentangle the different sources, processes and characteristics that shape N-cycling at these sites. Her findings indicate that in lowland lakes the residence time influences nitrate retention more so than trophic status, but in uplands, atmospheric deposition appears to be an important nitrate source. Both these talks were a timely reminder that nutrient management requires holistic consideration, and a recognition of land-soil-water interactions.

Community engagement

The penultimate presentation was delivered by Taylor Butler-Eldridge from the University of Exeter, whose PhD project “Swimdermere” explores outdoor swimming and environmental health. Over 12 months, Taylor has been to sites along the shores of Windermere over 100 times leading swim-along interviews and conducting lake hangouts. By engaging and immersing himself (quite literally) in the spaces of the outdoor swimming community, Taylor’s research provides understanding as to the motivations, experiences, and challenges of outdoor swimmers at Windermere. Understanding who, where and how communities are accessing the lake and lake information is invaluable to catchment managers and scientists who wish to work with these communities more closely.

The final presentation of the day from the FBA’s Trine Bregstein highlighted exciting developments in the long-standing citizen science “Riverfly” monitoring programme. Riverfly involves kick-sampling to collect invertebrates which are then identified with their presence/absence and abundance recorded. Scores are generated according to the pollution sensitivity of these different invertebrate groups, and if scores fall below an expert-determined trigger level, these are then passed on to the Environment Agency to follow-up. Updates to the database mean it will become easier to track trigger breaches and their follow-up.

The spatial reach (103 catchments monitored in 2022-2023) and interest in Riverfly continues to grow (4253 surveys uploaded to the database in 2022-2023), with Riverfly offering “Urban” and “Extended” programmes to quantify a wider range of aquatic invertebrates. It is also now developing and testing a Riverfly scheme for standing waters. This is very much in its early stages and more trials will be conducted in the next few months.

Wrapping up

To wrap up the day, we had a discussion around the challenges of implementing best management practice in freshwaters. There was a resounding agreement that long-term accessible and sustainable funding remains one of the biggest challenges to managing freshwaters, often dictated by political and societal trends rather than environmental or societal necessity.

The need to work in diverse and multi-disciplinary partnerships was seen as paramount, but difficulty in translating complex priorities and coordinated action requires perseverance and patience. Inclusive public engagement was also highlighted, with suggestions to collaborate with experienced storytellers, outdoor brands, and social media experts. The Cumbrian Lakes Research Forum underlines the importance of working creatively and collectively. We look forward to sharing more learnings and research at next year’s hybrid event. 

Heather Moorhouse