Fully-funded PhD: The impacts of introduced Large Woody Structures on aquatic macroinvertebrate diversity and sediment dynamics in UK river systems

This research will investigate how aquatic macroinvertebrate assemblages and sediment regimes change following the introduction of large woody structures (LWS) into river systems. This understanding will contribute to river restoration and flood alleviation practice by quantifying the public good that LWS can offer when designed strategically to maximise biodiversity and habitat gains. 

Limited previous research shows that LWS used as engineered log jams for natural flood management (NFM) projects can offer improvements in the aquatic invertebrate assemblages and create localised temporary sediment storage for fine silts and sands, but we do not understand what controls the extent of these benefits in space and time. 

This research will use distributed field data collection (macroinvertebrates, sediment character and dynamics) and a complementary set of flume experiments to quantify these impacts and to systematically investigate which local biotic and abiotic factors control the extent of LWS-related biodiversity and habitat improvements across a range of different UK river systems. The project will be of significant benefit to practitioners working in river restoration and NFM as the research will expand our knowledge and understanding of the role artificially placed LW plays within the stream ecological and geomorphological processes. 

At Manchester Met, we are committed to developing an inclusive and equitable research environment and we welcome applications from individuals of underrepresented groups in postgraduate research. The successful candidate will be part of a growing, vibrant doctoral community with access to our cutting-edge £117M Dalton Building.

Project aims and objectives

This research project aims to assess the impact of Large Woody Structures on aquatic macroinvertebrate assemblages and sediment regimes. It seeks to answer the following research questions:

The objectives are to:

• Carry out a desk review of, and collate, instances of LWD interventions across the UK and categorise and classify sites into intervention type, intervention age, catchment and river system type.
• Identify a selection of LWS sites (20<n<40) that together cover a broad range of river systems and intervention types, across gradients of those local biotic and abiotic environmental factors that are, a priori, hypothesised to drive positive impacts on macroinvertebrate diversity and sediment dynamics.
• Collect field data from LWS and paired control sites (macroinvertebrate samples for lab identification, channel long profiles, sediment characteristics and dynamics).
• Analyse through statistical analysis significant causal effects on the ecological and geomorphological outcomes of LWS introduction at these field sites.
• Test and extend outcomes of the field data analysis for geomorphological impacts using flume experiments that assess how key control variables (such as channel slope, sediment supply, LWS installation) affect sedimentation patterns and habitat generation.