Diagnosing and mitigating the adverse effects of extreme winter climate on salmonid spawning
School of Biosciences, Cardiff University
Project ID: CUK230
Annual Stipend: Doctoral stipend matching UK Research Council National Minimum
Application Deadline: 30 April 2018
Previous work in Wales and elsewhere has identified the sensitivity of rivers to climate change.
Amongst all freshwater organisms, Brown trout Salmo trutta and Atlantic salmon Salmo salar are particularly vulnerable to extreme temperatures in both winter and summer, and potentially also to extreme flows. The geographical location of Wales at the South West edge of the European range for these two species means that populations here could be among the first to be seriously impacted or even extirpated should climatic tipping points be reached.
Apparently widespread impairment to salmonid spawning and/or recruitment occurred in Welsh rivers in 2015/16, manifest as dramatically reduced fry numbers during juvenile surveys during summer 2016. In some rivers, parr numbers were also reduced markedly. These patterns imply potential effects on two year classes and followed unusually high temperatures during periods critical to spawning (December 2015) as well as exceedingly high flows during December 2015.
Working hypotheses to explain these effects implicate:
- potential thermal effects on spawning and pre-spawning fish
- potential thermal effects on egg survival and development
- downstream washout or displacement of fry and/or parr.
Given the importance of salmonids in Wales, there is now an urgent need to:
- diagnose the reasons for the impairment to salmonid spawning and/or recruitment in winter 2015/2016, and to identify the processes involved
- assess future risks to Welsh salmonids under possible climate-change future
- guide possible management action.
This proposed project will inform these diagnostic and future planning needs by:
- examining long-term trends in fry and parr numbers from available sites in relation to putative climatic drivers of change
- modelling the spatial pattern of thermal conditions across affected rivers in both surface water and interstitial environments using available data to assess how thermal patterns in main channels, tributary networks and locations at different altitude might explain spatial patterns in spawning impairment
- mapping and modelling thermal conditions and salmonid habitat availability across key Welsh catchments under different future climate scenarios to identify important refuge habitats
- reviewing and evaluating potential management options to protect salmonids in Welsh rivers under future climates (including extremes) and to increase resilience.
How to Apply
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To be eligible, the successful candidate will need to be resident in the convergence area of Wales (West Wales and the Valleys) on registration, and must have the right to work in the region on qualification.
Knowledge Economy Skills Scholarships (KESS 2) is a pan-Wales higher level skills initiative led by Bangor University on behalf of the HE sector in Wales. It is part funded by the Welsh Government’s European Social Fund (ESF) convergence programme for West Wales and the Valleys.