Climate change and glacier retreat in the French Pyrénées: implications for alpine river ecosystems

Khamis, Kieran (2014). Climate change and glacier retreat in the French Pyrénées: implications for alpine river ecosystems. University of Birmingham. Ph.D.

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Abstract

Climate change disproportionately threatens alpine river ecosystems due to the strong connections between cryosphere, hydrology and physicochemical habitat. Our general understanding of how these systems will respond to warming is, however, based on conceptual models derived from studies undertaken at relatively small spatial scales. This research utilizes: (i) field data collected from five glacierized river basins in the French Pyrénées; (ii) field based experimentation; and (iii) climate/hydrological modelling, to improve understanding of alpine river ecosystem change.

Despite a linear, harsh-begin, physicochemical habitat gradient running from high to low meltwater (snow and ice) contribution, observed benthic macroinvertebrate community level metrics were unimodal (i.e. mid-meltwater peak). Community assembly processes shifted from niche filtering/stochastic (trait convergence) at high meltwater sites, to limiting similarity/stochastic (trait divergence) at low meltwater sites. Benthic macroinvertebrate community structure, feeding interactions and body size spectra were altered when invertebrate predator range expansion was experimentally simulated.

Empirical observation (space for time substitution) and statistical modelling both suggest an increase in reach scale diversity (alpha) is likely as glacier cover is lost. However, a reduction in habitat heterogeneity is likely to lead to biotic homogenization (reduced beta diversity) as a specialist high meltwater community is replaced by a more generalist community. The need to consolidate monitoring strategies is highlighted and functional trait profiles are suggested as useful bio-monitoring tools for detecting future change.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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