WTT Blog Posts

Extinction of Experience

April was a quiet month for me as my academic commitments stole the lion’s share. But I can’t believe we are already at the end of May! May is probably my favourite month…. here in North Yorkshire, the ramsons and bluebells are in full swing and the beech buds burst to dapple them in shade and provide such a vibrant, fresh green for a week or so. And then there are mayflies of course but that’s another story.








I get an even stronger urge to be outside as much as possible, to immerse myself in the busy comings and goings of late spring. Luckily for me, the Conservation Officer role of my Wild Trout Trust duties (and occasionally my academic research) allows me to do so.

A month or so earlier, a paper popped up on my academic radar on ‘Extinction of experience: the loss of human-nature interactions’. It struck an immediate chord, having felt stifled and starved of those very interactions for the 10 years I worked in London. Fewer and fewer people, especially children, have daily contact with nature. This ongoing alienation prompted Robert Pyle to coin the phrase ‘extinction of experience’ some 20 years ago. The authors of the current paper report that some consequences of the loss of interaction with nature include deteriorating public health and well-being, a reduced emotional affinity toward nature, and a decline in pro-environmental attitudes and behaviours, which implies a cycle of apathy toward nature. They recommend that the policy makers of today need to focus more attention and effort on planning how best to reduce the extinction of experience and reconnect people with nature. The benefits seem obvious: achieving a healthier society and overcoming a wide range of environmental issues.

I am a proud father of a three year old daughter (the ‘Greyling’ - a definite PB), and such things play on my mind. I want her to have the opportunity to experience nature as I did. And I get an enormous kick from her curiosity toward nature. ‘Hornathorn’ (hawthorn) trees smell funny apparently. Sung to the tune of Rudolph the red-nosed reindeer (about our bird feeder frequenting pheasant) is ‘Ferdy the gaudy birdie, has a very splendid tail’. And whenever I pick her up from nursery with a rod wedged next to her car seat there is the inevitable question, ‘Yuk, do trout really eat flies like that?’    

Strikes me, although I am biased, that fishing is a great way to counter the extinction of experience. There’s the simple, out-of-the-house (off the sofa / video game) aspect, a curiosity angle of not knowing quite what might emerge from under the water, welfare and respect for other creatures stemming from catch and release, as well as all the other wildlife that we hear and see on the bank or which we can turn to when we blank! We will all have some experience that springs immediately to mind. This year especially, The Angling Trust have been trying to help young people create opportunities via their scheme Get Hooked On Fishing. My daughter has been kayak fishing with me several times on holiday and loves it. She’s chief shark spotter on the prow!

Riverfly monitoring is another great scheme to engage and mentor young people and instil a sense of environmental stewardship, but speaking from personal experience (and I would dearly love to be wrong) I haven’t seen anyone below the age of twenty doing it. I have spent many an hour with the Greyling, poring over a plastic tray, surreptitiously using her keener eyesight to best effect. So, are we missing a trick? There seems to be a distinct need to maintain the momentum gathered from all the fantastic ‘trout/troot in the classroom’ schemes around the British Isles now that I blogged about back in January, and forge links to riverfly groups and youth angling opportunities. Maybe that way, and with the Environment Agency considering a free licence for juniors under the age of sixteen, we will finally see a decline in the number of juniors taking up fishing and perhaps the slowing of another extinction event…..

Mike Blackmore's 'Mad March'

Mike is the WTT Conservation Officer for the South and West. 

At this time of year, there is often a hectic dash to get money spent before the end of the financial year and get trees pollarded/coppiced/hinged before the start of the bird nesting season. March 2016 was no exception and my very understanding wife allowed me to work through three weekend days and a bank holiday to fit it all in.

On the River Biss just outside Trowbridge, some delicate chainsawing and back-wrenching rope-pulling was undertaken to demonstrate different ways of managing fallen trees without removing them from the river. The largest of these was tackled by Land Rover and winch but the rest was done on volunteer power alone.

A short skip across the border from Wiltshire to Somerset and eight days were spent in the river officially known as the Somerset Frome (to distinguish it from the Dorset Frome, Bristol Frome or the Gloucestershire Frome) but known locally as the Frome Frome after the town Frome through which the Frome flows (At this point it is important to note that if the eight times you just heard Frome in your head, it rhymed with 'home', you’re saying it wrong! Now read it again and this time rhyme it with 'broom'. These things matter in the Westcountry!)

This project involved using live willow to protect eroding banks, hinging trees for marginal cover and transforming a straightened, silty backwater into a sinuous and flowing fish nursery.

The sixteen volunteers that gave up their time to help out, and the ever helpful Council Rangers worked extremely hard and should be rightly proud of themselves. The project has kick-started further improvements and provided a platform for further fund raising by the Bristol Avon Rivers Trust.

Both projects were funded by rod license money from the Environment Agency team at Bridgewater and a special mention should go to Technical Fisheries Officer Matt Pang who helped out in between nights spent patrolling for eel poachers and doing shifts in the family chip shop. This after not long becoming a father – who needs sleep?!

Photos: Somerset Frome project phase 1 . The project included a green erosion repairs, junk removal, juvenile fish/marginal plant habitat enhancement and a bit of river restoration.

MB frome work


 MB frome







MB frome 3

MB frome 4







MB frome 5


MB frome 5







Before and after shots of how the brushwood berms filled up with silt after just ONE day’s high flows. Exactly what we want to allow plants to establish.

Frome berms  MB frome berms with silt


What do we need, to know if it works?

Typical! Not two weeks after completing my round-up for the Science Spot in Salmo trutta, the annual glossy WTT publication that our members receive, an interesting paper on IMWs (Intensively Monitored Watersheds) lands on my desk. While not exactly on topic, it includes interesting snippets that would have embellished my article. However, as I wrote in the Salmo piece, the means by which knowledge is transferred nowadays means: I can (and have already) tweeted about this paper (but not included any precis or personal view of its content); I can (here, now) blog about it and impart some detail; or I can sit on it for 12 months and tell you all about it in the 2017 issue of Salmo!

IMWhats? In the Pacific Northwest, a vast tract of land with a very loosely defined boundary but it’s roughly 67 times the size of Wales if you’re interested in that sort of thing, there are at least 17 IMWs. They are an attempt to test the effectiveness of a broad range of stream restoration actions for increasing the freshwater production of anadromous salmon and steelhead and to better understand fish–habitat relationships. This is no mean feat, and the paper by Bennet and his colleagues reports on the lessons learned so far.

Billions of dollars have been invested in stream restoration across the US since 1990 alone, on the premise that improvements in freshwater habitat will lead to increased population viability and the potential delisting of threatened or endangered species. To achieve this, one needs to assess population responses to restoration, and these have rarely been documented because many restoration projects have not been monitored at the population scale. Instead:

  • Monitoring has tended to focus upon the reach scale and/or has occurred over too short a time period (less than 5 years). Experiments need to be 10 years or.
  • Restoration projects have typically been of a small size relative to the size of the watershed, and include a variety of restoration ‘actions’ such as culvert removal, reducing diffuse pollution, and installation of large woody material, which confounds an assessment of the effectiveness of each individual restoration type.
  • Identifying good ‘control’ streams to compare responses against is difficult, and it is also difficult to guarantee that control streams will remain suitable for their intended role for the duration of any project.

Add to that, inherently high natural environmental variability; all these contrive to limit power to detect a response in any one fish population. As an aside, these are exactly the underlying factors that affect our assessments of natural flood management, particularly pertinent in light of recent winter spates and ongoing reviews of how we will respond to those in the future. One of the closest analogues to an IMW we have in the UK, in terms of detailed monitoring of a population, not the efficacy of restorations, is provided by the long-term Atlantic salmon research on the River Frome; small scale by comparison, yet still valuable to inform stock management and conservation measures.

So, an IMW is an experiment that uses a management action (restoration) as a treatment and intensive monitoring to detect whether a watershed-scale fish response to that action occurred. The required scale, in both space and time, mean that this is an expensive business and not the sort of undertaking that can be applied to a typical WTT restoration! Also, because the IMW concept uses broad-scale, long-term ecological experimental designs, the expectations of stakeholders need to be managed carefully!

LWD woody material restoration river habitat wild trout trust

However, these sorts of ecosystem-scale experiments are required to provide the empirical data to test assumptions of improved fish populations, as well as provide reliable, robust and compelling evidence of the efficacy of common restoration techniques that are applied the world over (and certainly by WTT). If we drop X trees into Y barren stretches of straightened river channel, will the local angling club catch more fish because of it in Z years time?

While IMWs are still in their infancy, emerging data are positive, and the headline-grabbing figures are certainly encouraging:

  • Juvenile coho salmon survival in an Oregon river increased 50% in summer and 300% in winter after restoration improved rearing habitat.
  • 250% increase in numbers of juvenile fish in areas of a Washington creek with restored habitat compared to those without.
  • By helping beavers to construct dams to reduce erosion and boost the water table on an Oregon river, the production of juvenile steelhead correspondingly increased 175%.
  • Reconnection of side channels expanded habitat availability on a Washington river and fish numbers in those areas increased by 400-800%.

Each individual project undertaken by WTT (and the many other valuable works carried out by rivers and wildlife trusts, the Environment Agency etc) may fall into the ‘small size restoration’ category compared to an average IMW, but look at the number and coverage within the British Isles, and they start to tot-up. And as I have alluded to before here, we shouldn’t dwell on size because while they might not all add up to fish population increases, there are other benefits to be found.

Start 'em young

There has been much ‘Twittering’ of late as various organisations across the UK are venturing into classrooms to engage with children via aquatic beasties, and particularly our totemic species - the brown trout.

WTT chums at the Clyde River Foundation (CRF) coordinate #Clydeintheclassroom. It’s a huge venture, working with some 90 classes to engage with >2000 kids this year alone. It’s also very much a hands-on project, using aspects of the trout life history to promote awareness of river ecology, to engage with nature, and to help young people across the River Clyde catchment develop a sense of pride in their local environment. Furthermore, it provides a great basis for outdoor learning and STEM education.

Clyde River Foundation classroom education outreach enegagement science trout

On a recent visit to chat with Willie Yeomans, Catchment Manager at CRF, I learned that through the project, they have engaged with over 20,000 children at almost 400 schools. Check out the info-graphic above; that's some reach! Willie is keen to point out that on the Clyde, the trout are not used as part of a stocking project but purely as an educational tool; they’ve used triploids for a number of years now.

I’ve also been chatting with Gareth Jones, Catchment Science Coordinator for Ribble Life Together at Ribble Rivers Trust. Within the Ribble catchment and currently only in primary schools, they operate #troutintheclassroom with similar aims to those of Clyde RF. At Ribble, they are building upon the trout life-cycle by adding a variety of new activities from angling development / coaching, invertebrate monitoring, mayfly in the classroom, demonstration tables for river form and functioning, to poetry and musical events. Check out some of the enthusiastic school blog posts available on Burnley’s Urban River Enhancement Site.

In my day, things like this were definitely 'extra-curricular'! Excellent ventures I'm sure you'll agree, and they are not the only ones, just two I have personally come across recently. If you are a Twitter user, try the #hashtags mentioned above to see the kids (and trout) in action!

WTT has for a long time offered a similar educational project - Mayfly in the classroom – with free, downloadable resources on the WTT website, here.


Sediment sources and salmonid successes

Village pond weir dam sediment

On my WTT-inspired ramblings recently, I came across a shocking sight, above. Shocking because firstly, I was expecting to see a village pond complete with a raft of local ducks bobbing around, not a barren mudscape stuck behind a defunct dam; and secondly, because I immediately started to wonder where all that accrued sediment was being washed away to….. and where it was being deposited… and might it not be being dumped upon some salmonid redds at a rather inopportune time?

Sear sediment source salmonid embryo alevin

And a couple of days later, I was alerted to this. The image above depicts the graphical abstract of a recently published research paper by Professor David Sear, a key figure on the WTT Scientific Advisory Panel. While fine sediments are known to be a cause of embryo mortality in benthic spawning fish species such as brown trout, most research to date has focussed on the quantity accumulating around eggs, rather than any 'quality' issues associated with particular sediments.

For instance, some sediments will be mostly mineral, while others will contain a proportion of organic matter; it is the latter component which could be particularly detrimental to salmonid (and other species') embryos because of the potential for microbial breakdown of that organic matter, thereby reducing oxygen concentrations available to the eggs.

David and his colleagues exposed the embryos of two salmonids, brown trout and Atlantic salmon, to different sediment loads from different sources. Importantly, source as well as mass of sediment affected spawning habitat quality. While brown trout were less sensitive to sediment impacts compared to salmon, both were markedly affected by sediments derived from sewage treatment works; even the results from damaged road verges was worrying.

The organic content was the key driver determining the impact of a sediment source. Moreover, the effects were still apparent in surviving alevin via reductions in mass, length and yolk sack mass relative to experimental controls, so the overall fitness of the progeny that make it through the egg stage is still compromised. Any detrimental impacts at the vulnerable alevin stage is likely to lead to population consequences later on.

This important research highlights the inadequacy of current metrics and sediment targets which are based on quantity of sediment of a given size, or total daily maximum loads, on the assumption that all fine sediments will have an equal impact upon aquatic ecology. It thus provides resource managers with the evidence to support the development of sediment screening techniques, enabling them to target particular sediment source control strategies in the landscape. Critically, these strategies must encompass the characteristics of the mobilised sediment delivered to waterbodies from specific sources and not just the proportion of different sources of fine sediment.

Being in a relatively upland location with little improved land surrounding it, and situated in a small village, I am hoping that the pond sediments I found are of low organic content. Plus, recent snow melt has hopefully flushed it rapidly through the system so it has not had time to settle on any favourable spawning gravels. Hopefully!

For access to the research paper, click here, and for further recent information on land use and soil impacts on rivers, click here to be taken to a WTT news item from last year.

Reflecting on all this rain

Lothersdale farm fields

This is the view from my office window. Of late, I have been lucky to see across the valley. When it has been sufficiently clear there has been a stark message staring me in the face. So, what’s wrong in this image? OK, it’s not a great image but then it was taken in blowing rain. The field (centre shot) has a similar slope / exposure as those surrounding it yet it is the only one veined with rivulets of water. It is also the only one under permanent livestock grazing as compared to the fields on either side through which stock is rotated regularly. The result is a reduced crop plant height, root structure (and probably diversity), and more compacted soils leading to serious (visible) overland flow during times of heavy rain. At the bottom of that field is a tributary of the River Aire; little wonder that the Aire is often occupying the full width of its floodplain (below).

Aire flood


Everyone and their dog has had a view on the recent flooding in Cumbria and Lancashire, and not surprisingly these views tend to polarise; those driven by raw emotion as personal possessions and property are lost or destroyed, versus more objective analyses based upon long-term data records. Inevitably there are some commentators calling for the construction of more and better flood defences whilst there are those advocating more upstream thinking and rewilding of the upper catchments to slow the flow by intercepting rainfall and buffering impacts downstream.

Let’s face it, we have to contend with a long historical legacy of denuding the catchment of natural vegetation and in particular trees, as well as the development of village to city scale infrastructure upon floodplains with vast areas of impermeable surface and many pinch-points on watercourses like bridges and culverts. It is difficult to envisage the scale of defences that would be required to withstand the unprecedented rainfall at the beginning of December (1 in 1300 year; CEH site). Certainly, the aesthetic amenity and access values of having a babbling brook flowing through a village, or river gliding through a town centre, i.e. reasons that those very sites were originally settled, would be lost completely. It is also estimated (from models, because obviously there are no empirical data available) that 100% reforestation of the upper catchment would be unlikely to completely prevent such a scale of flooding when the water reached more urbanised / less natural infrastructure in the lowlands.

For a very measured consideration of the role trees may play in soaking up excess rainwater, read this contribution to The Conversation. I say measured, the message is positive from tree planting programmes such as the Pontbren Project, which followers of WTT will have heard us talk about on numerous occasions. However, providing robust and replicated scientific evidence along the lines of 'X trees planted here saves Y households over there from flooding following Z rainfall' is difficult.

There are clear evidence-based benefits to be derived from an integrated approach involving the whole catchment (summarised in the UK National Ecosystem Assessment Technical Report, here). And there are tantalising glimmers of potential uptake of such measures with the Environment Secretary announcing the investigation of upstream options for slowing key rivers amidst the Cumbrian Floods Partnership goals, calls for increasing the existing target of 11 million trees planted by 2020 to be upped to 200 million (via Confor), and established projects for ‘slowing the flow’ such as that in the Vale of Pickering reported in the recent Environment Agency blog ‘Creating a better place’. There is clearly no point in simply ploughing money into flood defences at the lower end of the catchment and expecting them to withstand the brunt of the water conveyed there by a depauperate system upstream, a point raised again and again by George Monbiot, and plain for all to see, unfortunately, in Keswick and Carlisle.

The key is integration and that includes depolarising the ‘camps’ currently at loggerheads, such as the ‘rewilding’ versus farming contingent. There are undoubtedly opportunities for more extensive areas of woodland (re)generation in the uplands, but not to the detriment of farmers, who are in essence the cultural element that is critical to the survival of communities in such rural areas. Hence, upstream options need to be (carefully) put into place to complement any (hopefully) sensitive ‘softer’ engineering within our urban environments such as SUDS – Sustainable Urban Drainage Systems. I say softer engineering in the hope that the dredging debate does not rear its ugly head again. Constraining water to an overly deep channel and conveying it downstream as quickly as possible costs millions, requires costly upkeep, is typically reactive, and rarely works as recent events show; and the environmental costs are always high (see the WTT view on dredging).

There is no panacea, but by thinking holistically to embrace and fortify natural ecosystem resilience to extreme events, perhaps we can move away from the oft repeated rhetoric of flood defence.

Small land use changes reap big freshwater benefits

The UK landscape is a mosaic primarily of agriculture interspersed with woodland, grassland, urban enclaves and veined with river networks and wetlands. We should all realise by now that this pattern in the landscape has a marked effect on 'ecosystem goods and services', the natural benefits that the environment provides to us, and particularly those associated with freshwater. How we use (or abuse) the land, i.e. influence the landscape pattern, and the downstream consequences to water quality are a focus of the current consultation on diffuse pollution to which WTT has already responded (and I encourage you to do so too).    

A new study of an urbanising but predominantly agricultural landscape in the US draws upon data from 100 Wisconsin sub-watersheds and has important implications for managing and restoring landscapes to enhance surface water quality, groundwater quality, and groundwater supply. The study considered the landscape pattern in terms of composition (the type and amount of particular patches) and its configuration (the layout of those patches); and while both appear to have some bearing upon freshwater services, the composition had a stronger influence on water quality and supply. 

river Aire, erosion, buffer strip, land use, managementIn other words, tweaking the relative size of some of those patches in the pattern could bring about considerable benefits to freshwaters. This is especially important when considering that large-scale changes to the landscape will rarely happen. One of the small tweaks with a disproportionate benefit would be to increase the size of wetlands and buffer strips within the landscape, native vegetation placed between cropland and lakes and rivers, with the multiple benefits of providing shade, bank-stability, litter and shelter, whilst taking up nutrients and trapping soils (reducing erosion) from the land. To many recipients of WTT Advisory Visits, this should sound very familiar! Compare and contrast the river banks in the image here: on the far bank there is a fence and (narrow) buffer strip; on the near bank, there is no protection and the erosion is evident. A picture paints a thousand words, but do we necessarily take heed?

In essence, the study above is landscape scale support for some of the very small scale mitigation measures advocated, for example, by my colleagues at the Lancaster Environment Centre (and in collaboration with the Game & Wildlife Conservation Trust). In a report card for the European Commission, they summarise some of their published findings on how small artificial wetlands created in the corners of agricultural land can prevent soil loss and recapture agricultural by-products, thereby reducing pollution of nearby watercourses. Simple, but oh so effective. WTT Conservation Officers spent a very interesting day at the site of this work, Loddington in Leicestershire, earlier in the year.


Making Connections

Man-made barriers, obstacles, call them what you will, are commonplace along our waterways as we have (typically) in the past tried to harness or control the flow of water for our own use. Some of these installations were incredibly insensitive to the local and more widely spread ecology and physical processes in rivers and streams, not just the fish that might want free passage both up and downstream at all life stages, and in all seasons.Swanside Beck, low cost baffle, weir, Ribble Rivers Trust, connectivity

I recently spent an afternoon with Mike Forty, a PhD student registered at Durham University, and based with the Ribble Rivers Trust. His work, using telemetry to assess the efficiency with which fish can pass obstacles, has been enlightening, and some of the statistics he can rattle off are mind-boggling. His work was featured in the presentation that Jack Spees (Director of RRT) gave at our recent WTT Gathering and captured on video here. For example, the low cost baffle system that was installed on a previously almost impassable weir on Swanside Beck (picture to right) can now be ascended in 23 seconds (according to one sea trout), and several resident brown trout have been up and down it numerous times!

Canal & Rivers Trust, weir, connectivity, Eshton BeckAnother of these low-cost baffle systems is being installed on Eshton Beck. Kevin Sunderland (Aire Rivers Trust) has been a driving force for connectivity issues with weirs, not only here, but throughout the Aire catchment. The Canal & Rivers Trust are undertaking the work in consultation with the local Environment Agency and I went along with Pete Turner to see them in action (pic to left). The design was drafted so that the gauging component of the weir would not be affected by any changes in flow over the crest.

This structure is ~0.5km upstream of the confluence with the R Aire, and by my reckoning after a swift glance at a map, should open up ~15km of potential stream network. This could be particularly important for trout and other fish from the Aire that are severely limited in spawning habitat within the mainstem channel. I wonder if Bradford City Angling Association catch returns will demonstrate and noticeable increase in smaller size classes of trout over the next few seasons?

Check out the new app which will hopefully allow the public at large to contribute to identifying and prioritising river obstacles wherever they may be.

Pre works assessment for Eastburn Beck

Eastburn Beck is a tributary of the River Aire in Yorkshire. It is typical of a northern freestone stream / river that has had a chequered history with industrialisation, and as a consequence, it has lost some of its vitality to the constraints of walled banks and a host of weirs. The walls keep long sectioEastburn Beck stream river weir conectivityns straightened and have allowed housing to develop on what would have been a far more sinuous, meandering floodplain. The weirs interrupt the natural progression of pool-riffle sequences and have choked the supply of gravels downstream.

The result is a series of impounded shallow sections with uniform depth, flow, and substrate on the bed, and little in the way of cover within stream. While some of the overly wide, shallow sections with plenty of jutting stones creating small pockets of turbulence provide excellent habitat for juvenile trout (and is also favoured by the local pair of dippers), there is a distinct lack of spawning, fry and adult holding habitat.

Trout can be observed in the impounded sections, but that’s not really good news as it is likely that they can also be easily picked off by predators such as heron, goosanders and mink. There is simply very little habitat structure to provide refuge.

As part of a funding bid with Pete Turner (Environment Agency, and driving force behind the Upper Aire Project which recently won the Large Project Category in the WTT Conservation Awards), and in close collaboration with Don Vine (Yorkshire Wildlife Trust), I have put together a proposal to ‘rewild’ some of Eastburn Beck. This is following up on some valuable pilot work by Kevin Sunderland (Aire Rivers Trust) to address connectivity issues. The aim is to improve the habitat for invertebrate and fish communities alike - and by improve, we mean we want to diversify the habitat and make it into a richer mosaic of habitat types which will cater for all life stages of bugs and fish.. This will involve exploiting some of the weaknesses in tEastburn Beck EA Environment Agency electrofishing trouthe redundant weirs and then letting the coming winter spates do some reorganisation of the gravels into hopefully a more natural channel form (yet still within the confines of the walls). Then we will assess what further augmentation is required.  

But how can we measure the success (or not) of our venture? Before we do anything in river, it is important to collect some background and reference data. Essentially, we are conforming to a Before After Control Impact (BACI) experimental design. Sampling before and after any remedial work at the impact sites can be compared to samples before and after at unaffected reference (control) sites; we would expect negligible or little change at the control sites and hopefully some measurable positive changes at the impact sites!

So, to get the ball rolling, Pete organised colleagues from the Environment Agency Yorkshire & NoEnvironment Agency trout survey Eastburn Beckrth East fisheries team to electrofish 50m sections of Eastburn Beck and conduct a preliminary River Habitat Survey for those same sections. A more detailed report will be forthcoming but the population of trout was lower than might be expected, and the size distribution heavily skewed towards smaller individuals, as one might predict from the current habitat available. A few bullhead were also evident.  

The next step is to initiate some riverfly monitoring and to hopefully engage with the local community who seem very passionate about the beck where it flows alongside Lyndhurst Wood near Glusburn. Keep tabs on the development of our project here.

It’s not the length that matters….

Does river habitat restoration have to be a certain scale before it can be considered beneficial to the wider ecology of a river? It’s a question in one form or other that our WTT Conservation Officers often get asked. Is it really worth putting that one log deflector or hinged willow etc into that reach? Without the time or resource to conduct a robust scientific study, we’re often simply basing our opinions upon experience of what has seemed to work before. Despite the increasing number of river restoration projects being initiated across the world, scientific evidence on the long-term impacts of such projects and what makes them a success or a failure is still quite thin on the ground.

Well, apparently it is worth doing at the small scale according to some new research, provided that quality and diversity of habitat are accounted for.

As part of a large project involving sites across 10 different regions of Northern Europe, a research team has studied the effects of two restoration projects in each region: one on a short section of river and one on a longer section. At each restored section, the team not only sampled habitat composition in the river, but interestingly also its floodplain. To complement this, they sampled aquatic plants, insects and fish, as well as floodplain vegetation and ground beetles, and the food web composition and any land–water interactions across the boundary between the two.  These findings were then compared to samples taken upstream at non-restored sections of river of roughly equal length.

After accounting for potential variations in river size and restoration approaches across the different regions, the team found that the length of the actual restoration made no significant difference to its apparent ecological health and the diversity of life within.  The most important driver was the substrate composition of the river bed, i.e. the aquatic habitat it provides for organisms. So, exactly the sort of measures that WTT advise on and instigate to rehabilitate river habitat such as increasing the presence of wood (e.g. tree kickers or hinged willows) to diversify water flows and depths and sort gravels, were found to be responsible for increased populations of fish, aquatic insects, aquatic plants and floodplain vegetation.

Perhaps one of the most interesting findings was the marked effects that were felt beyond the boundary of the river and into the actual floodplain. In-river restorations tend to improve the linkage between the water and the land by creating habitat types close to the river bank, such as bars of deposited gravel and sand, which are often absent in degraded sites. These are readily colonised by floodplain plants and animals which have good dispersal ability.

The study (available here) provides further scientific evidence underpinning some of the holistic restoration work that WTT does to improve habitats, not only for trout, but for all flora and fauna living in and along our river corridors.

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