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Responses of river life to channel changes
- 1. Investigating the responses of in- channel biota to the hydromorphological modification of river channels. Anna Doeser Supervised by Dr Nigel Wilby, Prof David Gilvear and Chris Bromley (SEPA)
- 2. Spatial scales of influence 40% 10% 20% 20% 10%
- 3. Factors explaining current biological and physical composition Temporal scales of influence hoursdaysweeksmonthsyearsdecadescenturies
Editor's Notes
- Introduce self Project title Supervised by…… Funded by SEPA thought the IMPACT studentship
- Take this small patch we might survey for its invertebrate composition and sediment characteristics to represent the river reach The current ‘snap shot’ taken in this sample of the abundance, diversity function or other characteristic you might survey are a Reflection of………… The physical and biological elements and processes at spatial scales ranging from individual sediment particles and flow streams to the entire draining network So what is observed here integrates to some extent what has been going on in other parts of the stream and wider landscape not sampled How important activities at other scales depends on the site and its history We could suppose that… Click 40% is a result of v small scale actions in the sampled patch 10% - from the patches neighbouring small scale patches 20 % from other channel features 20% from wider channel and riparian influences And 10% from wider landscape
- So thinking now about the sampled patch and the effects of processes and events occurring over temporal scales to explain our observations The current biological and physical composition and function of the patch at the observed time will be an integration of things going on over longer timescales Over hours short term movements of individuals Days – effectts ofo movement of predators Weeks – residual effects of recent high or low flows Months – see seasonal patters of drough, seasonal snow melt Years – intructions of invasive spc, longer term channel readjustments You get the idea… The spatial and temporal variables add up to a nested hierarchical system in space and time, with many elements interacting through complicated mechanisms often with the influence of feedback and the uncertainty of thresholds needing to be met before change is experienced The relative importance of factors at each scale probably varies between systems and will have a natural range that the system has evolved with – additional pressures will alter these patterns