PhD Student Jingrui Sun recently completed their studies titled:
CONNECTIVITY RESTORATION FOR FISHES IN
POST-INDUSTRIAL RIVERS OF NORTH EAST ENGLAND
Many rivers in developed regions experienced a strong decline in ecological function
during the Industrial Revolution, due to poor water quality, degraded habitat and
diminished hydrological connectivity. Post-industrially, water quality has dramatically
improved in many rivers, and clean-water indicator species have returned, yet such rivers
often remain very fragmented by river engineering, with locally degraded habitat and
resultant effects on ecological communities, especially of fishes. River restoration
activities are widespread, but their effectiveness in restoring biodiversity and ecological
function remain poorly known. This study explores the causes of decline of fish
populations in rivers of industrial North East England, their partial recovery, and the role of
river restoration, especially through removal and mitigation of anthropogenic river barriers.
Jingrui Sun has just published a peer-review paper from his PhD thesis that provides one of the first medium-term assessments of fish community and abundance responses to connectivity improvements at a sub-catchment scale.
It shows that:
a) Connectivity improvements, especially barrier removals, have helped naturalise stream hydromorphology through sediment transport, increasing riffle area and reducing fine sediment.
b) After a delay of 3-4 years, specialist stream fishes such as trout (highly mobile) and bullhead (poorly mobile) have increased their abundance markedly, and a higher proportion of the Deerness trout are now migratory (due to fewer obstacles).
c) At a subcatchment scale, the fish community remains unchanged, although there are local differences. Stone loach, which are tolerant to fine sediment have become less abundant; eel have become more abundant and widely distributed, but remain rare.
d) Salmon remained absent over 7 years of intensive sampling (OK EA caught 1 juvenile in very lowest Deerness reach), suggesting a hysteresis effect in decline vs recovery.
e) Locally, small barrier removal benefitted habitat naturalisation and stream fishes much more than nature-like / rock ramp fish pass provision.
f) Milestones for expected recovery after longitudinal (upstream-downstream) connectivity restoration need to be set on realistic timescales of at least 5-10 years and may only be achieved after the majority of barriers have been removed/mitigated (and remain dependent on there also being good water quality, and habitat).
Following a busy week of planting, we have completed our 3 natural flood management (NFM) sites located along Alderdene Burn. These consisted of 550m of new hedging and 2 riparian woodland sites, 0.14 ha and 0.5 ha in size, funded by our project partners at Durham Woodland Revival. These sites were chosen following drone and walkover surveys of the area which were then used to identify the locations in which surface runoff was a particular problem and therefore where NFM interventions would be most effective. As they mature, the hedge and trees will intercept surface runoff and slow the rate at which water enters Alderdene Burn. The species used for the hedge were chosen as those which are native and traditional for hedging in the local area, whilst also being beneficial for pollinators through their staggered flowering times. The riparian woodland species are also native and were chosen not only for their high water tolerance but also for their ability to quickly become established and spread as this will help the area begin to intercept water more quickly and effectively.
A huge thank you goes out to everyone who helped us with the planting, including the Skill Mill, local volunteers from Lanchester tree planting group, and WRT staff and trustees. We would also like to thank Penny and Neil Davies for their generous financial contribution towards helping the trees to become established, it is much appreciated and will give them their best chance of reaching maturity and providing the intended NFM benefits.
In earlier phases of this project WRT have worked with local landowners to fence off watercourses, improve gateways, create storage ponds and build leaky dams. Further leaky dam creation, fencing, drinking point installation and improvements of a final gateway are due to be made in the upcoming weeks which will complete the Alderdene Burn NFM Project. These interventions will all work in combination with the tree and hedge planting to reduce soil erosion and slow the flow of water in Alderdene Burn, helping to protect Lanchester from flooding for years to come.
The Cong Burn fish pass was installed 2012 to raise the water level around a 3 ft weir carrying a sewer pipe to an adjacent Sewage Treatment Works. The photo looks downstream toward the confluence with the Wear. The RH bank, looking downstream, has been revetted with10ft vertical larch logs driven into the bank base, reinforced with horizontal larch rebarred together and backfilled with willow brash. The brash successfully regenerated and has since grew to a size where it should be coppiced next winter and used for bank revetment elsewhere. The revetment at this site prevented the burn eroding around the fish pass.
Looking upstream with the larch and willow bank revetment on the left. The rock ramps increase the elevation of each pool until the weir is submerged in the smooth water glide above the top rock ramp. The whole rock ramp can often be covered with gravels, resembling a natural graduated riverbed, when the main river holds up the flow of the Cong burn and sediments drop out of suspension. These gravels are scoured away at times when the Cong burn is flowing strongly, and the main river is low.
Looking upstream from the footbridge just above the Wear confluence. The larch and willow revetment can be seen along the full length of the LH bank with the rock ramp in the distance. The shot is sadly not enhanced by the plastic sheet hanging off the tree.
This view shows the regenerated willow grown from the brash used to backfill the larch logs. These trees should be coppiced not only to provide native woody material to be used elsewhere, but to prevent them becoming top heavy and destabilising the extremely sandy bankside. One for next winter…
Prince Charles launched the Terra Carta or Earth Charter 10 January 2021 https://www.sustainable-markets.org/terra-carta/
Extract from the foreword by HRH The Prince of Wales: “The interdependence between human health and planetary health has never been more clear. As we start a new decade, it is time to focus on the future we wish to build, and indeed leave, for generations to come....… To build a productive and sustainable future, it is critical that we accelerate and mainstream sustainability into every aspect of our economy.”
WRT completely endorses this approach toward commercially and environmentally sustainable private business and wishes to promote the practical application of these principles locally in our catchment and across the region.
Useful Guardian Article with links https://www.theguardian.com/environment/2021/jan/11/prince-charles-businesses-terra-carta-pledge-planet-first-nature-age-of-extinction
The WRT are currently working with three local farmers and other partners to collect soil and water data to better understand how water and nutrients move through the soil under varying tillage regimes. The Trust procured a MobiLab that will be used to analyse soils at depths of 300mm, 600mm and 900mm measuring the levels of Nitrogen compounds across the crop rooting zone. For more information see the article below:
WRT Director Peter Nailon recently presented UK1's project summary to the Topsoil partners. This focused on soil health & and upcoming field investigations taking place in the Wear and Tyne Catchments,
After dispiriting news on the state of UK’s rivers last week, the Rivers Trust CEO Mark Lloyd looks to lift our spirits for World Rivers Day by highlighting some of the wonders that can still be found in our waterways. But, he warns that we need much more ambition if we’re going to spearhead the green recovery and rebuilding after COVID-19 that is urgently needed.
In recent weeks, we have seen several newspieces which make uneasy ready for nature lovers, especially for those passionate about protecting freshwater habitats. The WWF’s Living Planet Report showed the continuing decline of wildlife globally, with the biggest losses to freshwater ecosystems; the Environment Agency released new water quality data showing us that 0% of English rivers are in good overall health; and Sir David Attenborough’s latest documentary “Extinction: The Facts” gave a stark warning that extreme biodiversity loss places us at risk of further deadly global pandemics.
The good news is that we know what to do and we even know how to do it. In the past year, the Rivers Trust movement has led the way in delivering effective nature-based solutions, from new fish passages in the Severn and Don catchments unlocking our waterways for migratory salmon, to constructing wetlands to improve water management in urban areas. Our map of sewage overflow discharges throughout England has brought together data from numerous sources to make them available, free of charge, to everyone. This is linked to a significant surge in interest in introducing designated bathing water standards in UK rivers following the launch of our Together for Rivers campaign, with the River Wharfe in Ilkley vying to be the first site to achieve this.
Despite all this great work at a local and catchment scale, our rivers are as unhealthy as they were 3 years ago. If we are to turn things around, it is imperative to keep collecting good, clear data on the health of our rivers. We also need an honest conversation at a national scale about the really big decisions that need to be taken, such as whether we are prepared to invest HS2-equivalent sums to modernise our drainage and sewerage system; what public goods we should expect in return for farm subsidies; and how polluters are going to be properly regulated so that their actions don’t heap costs onto the rest of society.
Finally, we need to dramatically improve public understanding of the water system so that we massively reduce the impact of chemicals washed down drains, the profligate waste of high quality drinking water, the sanitary products flushed down toilets, the misconnections of washing machines and dishwashers, and the poorly-performing septic tanks that collectively cause huge environmental damage.
As Sir David Attenborough said: “What happens next, is up to every one of us.”
The document brings together North East businesses of varying sizes who are involved in innovative work around the environment, climate change & sustainability. Download the article via the link below:
River water levels via Farson Digital