Mayfly

Spring is on its way...saw my first mayfly today at Kettlewell. Anyone know the family/species?

Ecology of rivers

The ecology of a river changes as you move downstream. The river continuum concept describes this. Rivers ecosystems were once seen as discrete entities. An ecosystem in the middle reaches was different and seperate from ecosystems up and downstream. Now the river is seen as a continuum with gradual changes as you move downstream. All ecosystems within a river are linked to those above and below. This could be through the spiralling of nutrients as they move with the current and cycle through the ecosystem or through the movement of energy and nutrients as fish and other taxa migrate upstream.

Whilst this shift in ecosystem type is seen as a continuum if we chose an ecosystem from the lower reaches of a system and compared it to one from the upland headwater sections they would appear as discrete and unconnected. For example the number and type of collectors would be completely different with the lower reaches being composed of species that can tolerate low dissolved oxygen levels. Shredders and grazers would be absent from the lower reaches but very apparent in the upland river system.

The movement of matter from the upland system to the lower system connects the two. And salmon or trout may connect matter whenthey smolt to migrate coastal zones and headwater streams. These long range migratory species transport nutrients between different sections of a river. Observing these changes is fascinating, trying to understand them as part of a continuum is complex. But rivers are the result of numerous intercating processes that link apaprently discrete sections and draw nutrients in from land based ecosystems. Conversely rivers deposit nutrients onto the land whenever they flood and indirectly transfer nutrents through species such as bats, herons and kingfishers. A river is never isolated, it is a response to processes on the land and is connected along its course and to the floodplain both in time and space. Rivers connect land, freshwater and sea.

Willow Spiling To Protect Farmland

Bank erosion of streams pollutes watercourses with fine sediments and phosphates that can disturb the local ecology. It also removes sections of the farm to be deposited downstream, either within the river or on someone else’s land when the river overtops it’s banks. There are numerous methods for controlling this process and so reduce the rate at which soils are lost to rivers. The obvious method is fencing the watercourse to remove stock from the bank side. This allows vegetation to flourish creating a strong root stock that binds soils together. But sometimes just fencing the river bank is inadequate as erosion has taken hold and every flood pulse takes another section of bank and then the watercourse begins to eat into fields.

More drastic hard engineering methods can solve this. Gabion baskets for example create a strong buffer between fields and water. Such methods can be successful but they operate against natural processes and so always look at odds with the landscape. Moreover they too can wash out adding an extra ugliness as they hang into the river spilling their gravel back to the water.

There are intermediate methods that are successful and work with the natural features of a river. Matt Neale, the local ranger for upper Wensleydale, has championed willow spiling to protect banks, and fields, from erosion. This method seems to do the trick on most occasions and adds habitat to the river providing refuge and shade for fish, birds and mammals such as otters. Having visited sites where the Eden Rivers Trust had successfully employed the method Matt identified sections of the Ure that would benefit from this method. The first place he trialed willow spiling was on the river Ure just below Hawes. Here the river was eating into the bank and soil was being lost rapidly from the farm with every high flow event.

The method is simple but effective. Stakes are driven into the river bed close to the bank, spaced at two or three metre intervals. Live willow rods are then woven between the stakes to provide a permeable barrier between the river and the bank. This helps to reduce stream power and thus erosion and it also slows the water enough to allow sediments to drop out behind the willow spiling. The bank then builds up as new sediment is deposited whenever the river overtops the willows. The added benefit with using willow rods is that they take root and flourish in these locations. The roots further bind the soil whilst the new tree growth slows the water down even further and more matter is deposited until the bank becomes completely revegetated. The habitat created by this is valuable and helps to protect farmland creating one of those rare win-win situations.

Since the first trial Matt has carried out the method on several other sections of the river Ure and Duerley Beck. He has refined the process and now builds up coarse gravel behind the spiling to encourage fine sediments to deposit out offering further protection to the willow rods whilst they take root. When possible soil is packed into the coarse sediments providing a substrate for the growth of bank side vegetation, again this further binds the bank providing a more stable environment which offers improved chances that the work will be successful. When it is appropriate the bank is reprofiled to create a less vulnerable slope.

All of the sites that Matt has worked on have been succesful with one exception. This is at a location where a large glacial deposit, possibly a recessional moraine, is eroding badly. The land slip is substantial and the processes causing the slip are not simply undercutting of the bank by the river since the slope has become unstable. These glacial desposits are unconsolidated, porous and permeable meaning that water seeps through them providing a good medium for failure points to emerge. Where the processes causing erosion have been caused by river water the method has been extremely succesful and the habitat created appears natural and undisturbed.

Soil Compaction

Many meadows and pastures suffer soil compaction due to the regular passing of heavy machinery and high stocking rates. This can increase run-off during rainfall events and result in the delivery of fine sediments and nutrients to watercourses that can have significant impacts on river ecology. Soil compaction also has impacts on farm yields. If compaction impedes the root stock from penetrating into the soil layers then plant growth, and nutrient uptake, is reduced. This can result in poor crops of silage and hay which are required for feeding stock through the winter months; which is especially important in upland locations where growing seasons are short and winters long.

There are methods to improve conditions where soil compaction has occured. Sub-soil ploughs can penetrate below the compacted layer and break the soil allowing root penetration. This is not always possible in upland regions where soils can be thin with bedrock and boulders close to the surface. Steep slopes can also hinder the use of sub-soil ploughs. Aerators are often a better solution in such locations. These simple rotary blades penetrate into the soil and through the compacted layer allowing greater yields due to oxygen replensihment of the soil and root growth beyond the compacted layer.

If this is carried out in conjunction with newer methods of slurry spreading then yields can be massively improved. Two methods that appear to improve nutrient uptake are dribble bars and slurry injectors. These reduce the liklihood of run-off and allow improved use of a nutrient resource. If carried out alongside aerators and soil testing, for nutrient levels and pH, then savings in time and money can be passed onto the farm enterprise. Often pH levels can be lower then optimal and testing can identify where lime is required. This raises the pH and improves plant nutrient uptake. Soil testing can also idnetify which fields have high levels of phosphates and so allows the farmer to reduce inputs saving them money on fertiliser purchase.

These kind of options, if built into the farm plan, can be beneficial to the farmer and help improve the ecological condition of rivers. Cost of the machinery can be prohibitive but presently there are grants that can help with purchasing the kit. For example Yorkshire Forward's Farm Resource Efficiency Programme grants (FREP: www.yorkshire-forward.com/helping-businesses/rural-businesses/funding/frep) will pay up to 60% of costs. It will even pay up to 50% of costs for the pruchase of one piece of kit for contractors. These grants can make such options feasible for the farmer, either to purchase the kit directly or through their contractors.

Hay time



Soil profiles can help identify if compaction has occurred



Slurry injector





Dribble bar on umbilical

Species found in the dales rivers

Some of the species found in the upland rivers of the Yorkshire Dales.

Brown Trout



Brown Trout Fry



Bullhead





Stone Loach





White Clawed Crayfish





Cased Caddis Fly



Minnows

summer sun

The rivers are very low after the long spell of dry weather. Askrigg and Newbiggin Becks are completely dry in sections and upstream of Worton the main Ure is turning green with algae. These periods of low flow, coupled with algal blooms, create seasonal bottlenecks that limit populations of fish and flylife. Algae can soak up the dissolved oxygen during the night, as plants switch from photosynthesis to respiration. During the early hours the river can become depleted of oxygen to the extent that severe fish kills occur. When the algae dies back it smothers gravel habitat and depletes oxygen as it decomposes through microbial action.

Under natural conditions upland rivers would be oligotrophic, or low nutrient, relying on seasonal inputs of leaf litter and dying salmon after spawning. But in urbanised and agriculutral catchments these dynamics are changed through the inputs of human-derived nutrients. It doesn't take much phosphate to lead to eutrophication (the change from a lower to higher nutrient status). When this occurs the ecology of the river changes too. This can be through reduced populations of typical species or invasions of species pre-disposed to survive under the emerging conditions. In dales rivers populations of fish, including salmon and trout, are lower then expected suggesting issues of pollution. But barriers, such as weirs, also limit their populations showing that impacts on rivers are multiple.

At one time pockets of de-oxygenated water moved with the tide along the Humber estuary stopping upstream migration of spawning salmon and trout, and downstream migration of smolts (salmon and trout that undergo physiological changes enabling them to live in saltwater). With more stringent regulations on industry, and the decline of the UKs indutrial base, this has been reversed and migrating fish stand a chance of reaching their spawning grounds. The rivers trust is trying to improve the habitat of these upland rivers to ensure that spawning streams are able to support populations of salmon and trout fry. Providing shade to river banks through tree planting, preventing cattle and sheep accessing rivers and adding structure to stream habitats (for example through the inclusion of large woody debris) all offer habitat for salmon and trount young.

River restoration

This is an exciting time to be involved in river ecology. Not only is river restoration becoming more research focused but the river itself is now seen as a system directly connected to landscapes by numerous processes and feedbacks. These riverscapes are constantly interacting with landscapes through hydrological connectivity and interspecies relationships meaning that the river is an integral component of the wider ecology of a catchment. More than this the morphology, ecology and quality of a river is governed by processes that work at catchment scales. For example in the headwaters of a stream it is the hydrological flow paths emerging at the upper reaches of the landscape that govern instream flow rates, discharge, sediment and nutrient delivery, river morphology and finally in-stream ecosystems.

In the past this lack of spatial context has often resulted in restoration that fails due to rivers not being viewed as am emergent response of the catchment. Tackling eroding river banks is a case in point. Management and restoration has often focused on the immediate surroundings of the issue, such as putting in place buffer strips, shoring up or reprofiling the bank. This is despite eroding banks being a symptom of upstream processes such as soil compaction, drainage or deforestation which all increase the speed at which water reaches the channel network and thus the erosive power of a river.

Now that these connections are being made river restoration is becoming process orientated and thus more likely to be succesful. Whilst this is exciting it also poses numerous difficulties. One such issue is that working on one location can result in the need to work with multiple land owners (as the focus shifts to upstream processes) some of whom are more receptive then others. This requires skills that go beyond knowledge of river systems into social science and negotiation and may require teams of multi-disciplinary practitioners in order to develop plans and inform land managers. Where such teams are in place river restoration is becoming more succesful and populations of indicator species such as salmon and trout are becoming re-established.

Winter in the Yorkshire Dales

Winter has hit the dales in a way it hasnt for decades. The riverscapes are surrounded in white that glistens in the low winter sun. Sheep huddle together behind walls waiting for deliveries of food that arrives by tractor which, despite their traction, also slip across the surface. The rivers are running low as all the precipitation is stored in snow and ice, the freezing nights keeping water locked up.

Cars have deep coverings of snow and roads look like gorges as the ploughs scrape them free of snow leaving steep edges on either side. The forecast suggests we have at least two more weeks of this and with drifts already reaching above head height the next days promise impresive sights.



The thaw is held up by the sub zero temperatures dipping to -8 in the dales and colder still the further north one travels. When this huge store of water eventually flows the rivers are set to rise substantially. The worst case scenario for those living in towns downstream of here is a rapid temperature rise coupled with rain. Such conditions will undoubtedly lead to flooding, and misery, for many.

Research into land management suggests that compacted soils and extensive drainage exacerbates flooding by shifting water rapidly from land to river resulting in sharp spikes in the hydrograph. The key to the next few years, as we move towards the prescriptions of the EU Water Framework Directive, is to understand how land management effects water and more importantly identify methods for improving conditions whilst making sure upland farmers do not lose income. This is an exciting time for freshwater ecology as local scale perspectives are stretched to the catchment scale which provides many of the controlling factors on river ecology and quality.

The incredible thing is that the whole country is white, smothered in deep drifts and layers of weeks of snow. Satelite photos from NASA display this strange image of the UK. It looks like not only Yorkshire rivers are at risk. In the meantime the landscape looks fantastic and we all hope the thaw occurs in a slow, steady manner.

Redmire falls

Its been a gusty start to the weekend with long spells of swirling rain interspersed with the brightest of autumn sun. The beech and ash trees are vivid yellows and deep coppers. You can follow the track of the wind as it passes and moves down the river bank by the falling leaves. In the strongest gusts it feels as though someone has picked up this pocket of the world and given it a good shaking. One moment the air is empty the next tumbling, spinning, leaves fill it up. The copper leaves twist and turn catching the sun so that they flash like polished bronze.

The river is slowly rising. Ive tried to cross it four times and each time its overtopped my wellies. I get halfway, even further, but am forced to turn back all four times. I got to the tight cataract of water where the river Ure is forced by an upward tilting ledge of limestone down into a bottleneck. This is where the fish will navigate upstream. Here I'm nearly at the far bank and can see that the beech trees are tapped directly into massive beds of grey limestone. Its hard to believe but their roots will force these rocks open, prise them apart so that they tumble into the river. It wont happen here for sometime I think but it will happen.

I have sat and waited here on numerous occasions but still not seen a fish jumping. Today this doesn't bother me because I'm fascinated by the movement of the leaves in the water as they get caught in the current or in eddies. The water by my feet is moving fast and right next to my foot a scour hole holds masses of leaves, they spin in tight circles caught by a twisting current. Its easy to see how pebbles caught in the same place would scrape out a circular pit. In other places leaves are caught against rocks or tangled in mosses. Below the ledge the deep pool is smothered in them. They are massing in rafts in the slower waters of the surface and underneath they move faster caught in the quickest part of the river. It looks like they are sliding beneath the surface leaves.

I sit and wait for an hour or so but nothing happens so I return to the bank and then wade through the shallow edges of the river watching a dipper drop from rocks into the water. It appears to be whirring round, its back causing a rise in the surface so that I can follow its tracks. Everything is spinning and twisting today.

There is a little stream that joins the river on the north bank. I follow it upstream and watch two more dippers, their wings blur as they fly rapidly upstream. Some of the gravel seems to be newly turned and I suspect Ive found a redd. It seems the perfect place, just enough current to replenish the oxygen levels, the gravel is the right size and this spot would only dry out in the deepest, hottest of droughts. I walk round it not wanting to compress the gravel. I think I'll see if I can electro-fish here next spring to see if I'm right.

Change and restoration

Upland rivers are fascinating places that possess a raw quality. Full of rapid change, violent spates to low flows in quick time, they pose challenges to people and nature. It is this rapidity of change that keeps them alive, keeps people drawn to them and puts their ecosystems on a knife edge of existence. One severe flood, drought, landslip or pollution event can alter their ecology for years. And when a natural system flips between threshold states dragging it back to its original condition is complex and challenging, beset with frustrating feedbacks and full of unexpected consequences. The new science of restoration ecology has discovered this time and again. What has appeared to be an obvious intervention can force a natural system to skew off towards some other state not accounted for during intervention planning. This has resulted in more measured approaches to reverse interference and has revealed that ecology does not exist in easily flipped parallel states but occurs in complex dimensions of interacting multivariate factors that we can never fully understand.

But not fully understanding something does not mean that we cannot understand it enough. Beneath the aesthetics of these places lie scale upon scale of interacting processes within and between both the living and non-living components of a system that create forever fluctuating conditions. However, even though they fluctuate, under prevailing conditions they are always pulled back towards some unknown average. In order to understand enough we need to simplify these interactions down to basic assumptions that explain them in as much detail that is required in order to predict the outcome of an intervention. This is not a magical process and can only come from experimentation both in laboratories and natural systems. And we are beginning to understand enough though it would be arrogant to suggest that we will never make mistakes during restoration efforts, but with restoration ecology it is the mistakes that guide learning.

The biggest experiment (and probably mistake) we are undertaking is one we have not planned but has come as a consequence of modern economies and lifestyles. An article published in 2007 in Global Change Biology by Durance and Ormerord showed that upland stream macro-invertebrate assemblages may decline by 21% for every degree centigrade rise in water temperature. This is of concern to freshwater ecologists as after primary production these are the most important components of upland river systems. What we have learned in recent years is that such a change would be difficult to reverse and as future temperatures are forecast to increase for sometime it may be that these upland river systems are destined to become shadows of their present selves.

October rain

After a September with little rainfall October 6th finally brought a decent spell of wet. The rivers responded rapidly swelling up and turing peaty auburn for the first time in weeks. By the time it cleared the Wharfe and Ure where racing and gathering pace. After a dry night they began to drop back and it seemed a good time to look for fish jumping. I headed down to Redmire falls armed with camera and a little hope. A Dipper was sat on a rock beneath Apedale beck and a Heron stood in the shallow edges at the far bank. It reluctantly took to the air, slow wingbeats just managing to get it out the water and away. I headed over the limestone 'steps' and down to the first set of falls. Getting my feet wet I found a good place to sit and I waited there, legs dangling against a mossy boulder, for a couple of hours till dusk set in but nothing stirred, not even a noticeable rise in the pool beneath the falls.

On the way home I stopped at Ballowfields to see if any big trout had moved into the stream there. Too high and fast to see anything. It cant be long now before the fish head up this way so I plan to maintain the vigil in the spare time I get. In the meantime plenty of mapping and writing to be getting on with.