In a rapidly changing world characterised by acute anthropogenic pressures, knowledge regarding the effects of environmental change on biodiversity is of key importance. Within-channel degradation of riverine habitats, often through excess fine sediment pollution, is amongst the most common and widely studied forms of freshwater degradation, with deterioration in spawning substrate quality through fine sedimentation associated with global declines in freshwater biodiversity. Despite this, knowledge regarding the environmental tolerances of many species, particularly during their early development, remains limited. This is particularly true for lithophilic (stony-substrate spawning) fishes. Whilst a body of literature on the influence of fine sediment content (“fines”) on the spawning success of some salmonid fishes exists, knowledge of the effects of fines and the variability of other environmental parameters on the spawning of other, typically non-salmonid species, remains limited, despite their ecological, recreational and socio-economic importance in many European rivers. This has consequences which transcend our understanding of fish ecology and without better understanding of the tolerances of river fish eggs and larvae to spawning substrate characteristics and variable abiotic parameters, we do not know whether in-situ spawning habitats are conducive to successful reproduction. This also means we do not currently have any readily quantifiable or transferable method of gauging the success (or failure) of river restoration activities in relation to species-specific environmental parameters or thresholds. In addition, some river restoration projects are limited in their success due to a lack of specific objectives, post-monitoring evaluation and/or consideration of landscape processes that provide the context for specific sedimentation problems. Thus, studies that utilise robust experimental designs are essential for understanding the factors that contribute to successful spawning habitat restoration. This project therefore aims to increase our understanding of the environmental tolerances of some poorly studied yet ecologically, recreationally and economically important freshwater fishes.

Further, spawning habitat, nest characteristics and levels of natural recruitment of target species (including barbel Barbus barbus, chub Squalius cephalus, brown trout Salmo trutta, and grayling Thymallus thymallus) will be assessed in the natural environment. The project will also investigate how degraded habitats might be improved to increase reproductive success.

Figure 1A Effect of sand content on cumulative daily emergence of barbel (Barbus barbus) larvae to the surface water column (filled circles = control; filled squares = 10% sand; blank triangles = 20% sand; blank squares = 30% sand; blank circles = 40% sand; adapted from Bašić et al. (2018)) and B Gravel jetting, used to remove fines from barbel spawning gravels in the River Great Ouse, UK.


The research will involve the acquisition of experimental data in field and laboratory settings. The project will involve an interdisciplinary approach comprising the following elements: (1) laboratory experiments utilising the Environment Agency recirculating aquaculture systems at their national hatchery in Calverton (Nottinghamshire, UK) to quantify environmental tolerances of eggs and larvae of one or more poorly studied lithophiles. Fitness physiology and/ or behaviour of emerged larvae may be monitored through time to assess legacy effects of conditions during early development. (2) A multi-river study of the spawning habitats, nest characteristics and recruitment of target species to develop better understanding of where, how and how successfully fish spawn in different rivers. (3) Field experiments to investigate the ecological and physical effects of some commonly applied spawning substrate restoration techniques.

Training and Skills

The student will develop a conceptual and theoretical understanding of lotic ecosystems, develop skills in dealing with large hydromorphological and ecological datasets and develop an understanding of data requirements to analyse internal dynamics and external stressors within freshwater ecosystems. The student will develop skills in fish identification, field sampling, data management, statistical analysis and physical modelling techniques. They will interact and collaborate within an interdisciplinary network of scientists and will have the opportunity to present their research at national and international meetings. The ex-situ experiments will provide the opportunity to work alongside Environment Agency staff at their national hatchery.


Year 1: Training in research methods, time management and experimental design. Review of literature on river restoration methods and environmental tolerances of lithophilic fish eggs and larvae. Examination of available datasets. Orientation with partner organisations and collaborators at the Environment Agency. Design experiments and field sampling campaigns. Training in fish sampling techniques and modelling approaches, including the identification of data requirements and interpreting data structures and patterns. Commence experimental data collection (incubation experiments at the EA hatchery). Initiation of data analysis (data from ex-situ laboratory experiment(s) in Calverton).

Year 2: Design experiments and field sampling campaigns. Main field and experimental data collection period which could involve: incubation experiments at the EA hatchery, field studies to characterise nest and spawning habitat characteristics of target species, fry surveys to gauge recruitment in study systems and/or controlled experiments to test the efficacy of in-situ river restoration methods. Analysis of data collected in years 1/2. Draft journal paper/ conference presentation, as appropriate.

Year 3: Incubation experiments. Analysis of data collected in years 2/3. Writing of PhD thesis chapters, draft journal papers and conference presentations to academics and practitioners.


Partners and collaboration (including CASE)

This project will utilise and nurture long-standing relationships with the Environment Agency, including undertaking an experiment at the EA national hatchery in Calverton, Nottinghamshire (UK). The project aims to foster new relationships with the River Anglers Conservation Group (RACG) who will help disseminate findings of the research to the wider public. The RACG will also provide access to secondary data via their “National River Fish Spawning Survey”, which may form a part of this project.  

Further Details

For further information about this project, please contact Professor Paul Wood (Geography and Environment, Loughborough University – p.j.wood@lboro.ac.uk). For enquiries about the application process, please contact the Department of Geography and Environment, Loughborough University (SocSciRes@lboro.ac.uk). Please quote CENTA18-LU5 when completing your online application form: http://www.lboro.ac.uk/study/apply/research/.