1. Implications of climate change for functional diversity in alpine river systems Khamis, K.*,. Milner, A.M., Hannah, D.M & Brown, L.E. k.khamis @bham.ac.uk

2. Meltwater: -low water temperature -channel instability -high suspended sediment -variable flow regime -high flow velocity Meltwater – Groundwater stress gradient Groundwater: -constant water temperature -stable channel and bed -low suspended sediment -constant flow regime -high flow velocity

3. Biodiversity and the meltwater gradient

4. Research questions How does community weighted expression of traits vary along the meltwater gradient? What are the underlying community assembly processes across the gradient? Do functional diversity changes along the gradient reflect taxonomic turnover? Reduction in meltwater

5. Study region The Pyrénées (42°- 43° N) - southern limit of European glaciation Rapid retreat since LIA maxima (~30 km 2 ice cover) 21 glaciers in the Pyrénées (5 km 2 )

6. Study region

7. Five glacier-fed river basins Gradient of glacier influence in each basin Variable geology/slope/basin area between study catchments

8. Methods: trait selection Trait groupingNumber of traitsRationale Maximal body size 5Small body size - resilience in unstable habitats due to reduced time to maturity Voltinism3Life cycle plasticity – resilience in unstable habitats Adult stage2Aerial adult - refugia from ecological unfavourable periods Reproduction8Egg laying - avoidance of scouring and abrasion Dispersal4Strong aerial dispersal resilience in unstable habitats Resistance4Freeze tolerance of eggs and larvae – resistance Respiration4Tegument respiration - resistance to high sediment loads Substrate relationship 6Clinger – resistance to high flow velocity Functional feeding group 6Feeding plasticity in stressed environments (no obligate predators) - Resilience Body form3Streamlined body - resistance to high flow velocity

9. Ordination : 3 table (RLQ) (72.3 %) (21.2 %) (72.3 %) Meltwater contribution Sites weighted by traits and environmental variables

10. Ordination : 3 table (RLQ) (72.3 %) (21.2 %) Sites weighted by traits and environmental variables Environmental stress

11. Ordination : 3 table (RLQ) (72.3 %) (21.2 %) Traits in ordination space

12. Ordination : 3 table (RLQ) (72.3 %) (21.2 %) Taxa in ordination space

13. Phylogentic Resistant Resilient P < 0.05 Regression of community weighted traits

14. R 2 = 0.28 ** R 2 = 0.65 ** R 2 = 0.36 *** RaoQ – abundance weighted measure of FD Fric – convex hull measure of FD Fric peaks at intermediate levels of meltwater contribution – not independent of species richness RaoQ negative relationship with meltwater contribution – independent of species richness Functional diversity patterns

15. Null models R 2 = 0.28 ** R 2 = 0.65 ** 1000 randomizations – shuffling trait matrix while holding richness and abundance constant SES: (observed FD - expected FD)/ SD(expected)

16. Null models Trait convergence Trait divergence R 2 = 0.28 ** R 2 = 0.65 ** R 2 = 0.36 *** 1000 randomizations – shuffling trait matrix while holding richness and abundance constant SES: (observed FD - expected FD)/ SD(expected) Mass effects obscuring patterns Env. Filtering – limiting similarity

17. Distance decay and redundancy Slope = 0.0026 Obs slope = 0.0020 Null slope = 0.0012 Taxonomic turnover Functional turnover

18. Conclusions Communities are structured along the meltwater gradient based on functional traits. Trait profiles sensitive to meltwater reduction have the potential to act as ecological indicators of climate change. Needs wider testing (meta-analysis) as biogeographic and basin specific factors may be important. Change in assembly processes along gradient - convergence - divergence of functional space. Taxonomic and functional turnover similar – replacement of functionally unique taxa along gradient.

19. Acknowledgements Parc National des Pyrénées Funding for project: ACQWA Logistical support: Richard Johnson Lab support: Mel Bickerton Field assistance: Lawrence Bird, Faye Jackson and Robert Senior