Landscape controls on downstream energetics for river ecosystem function and services

Project start date: October 2013 ( 3 year project)

Primary supervisor: Dr I Durance
Secondary Supervisors: Professors A Weightman & S Ormerod

This PhD will integrate three seminal components of river ecosystem theory in that: i) catchment character exerts major controls on downstream ecological structure and function (Hynes 1975) ii) rivers are characterized by upstream-downstream fluxes of matter and energy through the ‘river continuum’ (Vannote et al. 1980) and iii) river biodiversity and ecosystem functions deliver services of major societal value (Maltby & Ormerod 2011). In combination, these three concepts predict that land-use should determine key energetic subsidies to headwaters (e.g. through canopy leaf fall) that are then transported through river networks to affect ecosystem structure, function and services downstream.

This studentship will investigate these upstream-downstream linkages, specifically testing the overarching hypothesis that ecological structure, function and services in Welsh main rivers depend on energetic supplies from catchment headwaters. Any such energetic dependency on allochthonous (i.e. terrestrial) sources has potentially far-reaching consequences for wider landscape management and conservation.

The research will be tied closely tied to the large NERC-funded DURESS project researching the role of river biodiversity in sustaining ecosystem services in upland rivers (see: http://nerc-duress.org/ ). This £3 million NERC-funded endeavour is led by the project supervisors at Cardiff University, and it provides extensive data and investigative opportunities to support the PhD.
The student will address the project’s themes and questions using some combination of i) landscape-scale GIS; ii) modeling energetic sources and network fluxes; iii) energy source attribution using stable isotopes from river ecosystem components (e.g. seston, biofilms, invertebrates, fish, river birds…); iv) species’ composition, traits and productivity in main rivers draining contrasting headwaters; v) biofilm microbial function determined using molecular techniqies; and vi) experimental manipulations.

The supervisors (Dr Isabelle Durance, Prof Andrew Weightman and Prof Steve Ormerod) blend world-class expertise in spatial analysis, ecosystem ecology, molecular ecology and freshwater sciences and the student will gain transferable skills such as GIS, remote sensing, multivariate analysis, experimental ecology and the use of stable isotopes.