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.

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

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.

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.