PhD Studentship – Assessing the impact of pollution management on freshwater biodiversity
Freshwater habitats comprise a small proportion of the world land surface area (2.3%), but support over 10% of global biodiversity [1]. However, freshwater biodiversity has significantly declined in recent decades, recording greater species losses than terrestrial and marine environments [1]. This is principally driven by the unsustainable use of freshwater by people (e.g., for waste removal, industrial and domestic uses, and modern agriculture) [2]. In particular, habitat degradation (such as pollution) is a long term and pervasive issue that has underpinned reduced ecosystem functioning and freshwater biodiversity losses globally [3]. Pollution events can be ubiquitous (e.g., eutrophication) or can be unique to a particular location, reflecting the composition of contaminants (including traditional and emerging pollutants) and the origin of the pollutants [4]. The consequences can be lethal or sub lethal, and their interactions with other pressures can result in unexpected consequences [4]. In the UK, the release of raw sewage and stormwater into rivers has been extensive in recent years, with combined sewer overflow (CSO) discharge events totalling 372,000 in 2021 [5]. This, combined with other stressors (fine sediment increases, habitat modification) have resulted in declines in water quality, and impacted faunal and floral communities in UK rivers [8]. The impact of pollution is not only limited to the main river channel but can be catchment wide, as during high flow events polluted water and sediment can move onto the floodplain degrading important habitats such as ponds and mires [9] and have been shown to detrimentally impact terrestrial species, particularly soil invertebrates [10].
This is a fully-funded PhD studentship which includes a stipend of ÂŁ18,622 each year to support your living costs.
Key information
Next start date:
September 2024
Location:
Bournemouth University, Talbot Campus
Duration:
36 months
Entry requirements:
Outstanding academic potential as measured normally by either a 1st class honours degree or equivalent Grade Point Average (GPA), or a Master’s degree with distinction or equivalent. If English is not your first language you’ll need IELTS (Academic) score of 6.5 minimum (with a minimum 6.0 in each component, or equivalent). For more information check out our full entry requirements.Â
Project details
Freshwater habitats comprise a small proportion of the world land surface area (2.3%), but support over 10% of global biodiversity [1]. However, freshwater biodiversity has significantly declined in recent decades, recording greater species losses than terrestrial and marine environments [1]. This is principally driven by the unsustainable use of freshwater by people (e.g., for waste removal, industrial and domestic uses, and modern agriculture) [2]. In particular, habitat degradation (such as pollution) is a long term and pervasive issue that has underpinned reduced ecosystem functioning and freshwater biodiversity losses globally [3]. Pollution events can be ubiquitous (e.g., eutrophication) or can be unique to a particular location, reflecting the composition of contaminants (including traditional and emerging pollutants) and the origin of the pollutants [4]. The consequences can be lethal or sub lethal, and their interactions with other pressures can result in unexpected consequences [4]. In the UK, the release of raw sewage and stormwater into rivers has been extensive in recent years, with combined sewer overflow (CSO) discharge events totalling 372,000 in 2021 [5]. This, combined with other stressors (fine sediment increases, habitat modification) have resulted in declines in water quality, and impacted faunal and floral communities in UK rivers [8]. The impact of pollution is not only limited to the main river channel but can be catchment wide, as during high flow events polluted water and sediment can move onto the floodplain degrading important habitats such as ponds and mires [9] and have been shown to detrimentally impact terrestrial species, particularly soil invertebrates [10].
Water pollution in the UK has become an important issue socio-politically [11], with water companies now committing to invest in increasing the sustainability of water management infrastructure and practice [12]. For example, many water companies are increasing storm water storage capacity at the largest wastewater treatment works in the New Forest through installation of holding tanks, and will be piloting local community initiatives to reduce surface water runoff. In addition, Freshwater Habitats Trust (FHT) are leading work to reduce point-source discharges in the New Forest, including from campsites, farms, and private residences. Despite the ubiquity of sewage impact, little is known about the environmental and ecological impacts of the planned improvements; our study provides a unique opportunity to evaluate this impact which will be of international relevance. The New Forest provides an excellent case study and a rare opportunity to examine the effects of mitigating discharges due to the absence of other stressors in the upper reaches of the main rivers. We hypothesise that improving water quality (by reducing CSOs and other point-source discharges) should have a demonstrable positive impact on aquatic biodiversity, returning communities to a comparable diversity to proximal unpolluted rivers. However, there remains a major gap in our knowledge of the patterns in recovery of freshwater ecosystems to an improvement in water quality.
Aim
This PhD aims to quantify ecological (macrophyte, macroinvertebrate and fish) and functional (decomposition) responses to reduction in CSOs and other stressors across three major river networks in the New Forest, incorporating both the main channel and adjacent floodplain habitats. By examining the impact of water quality improvement across a freshwater landscape, incorporating ecological and functional components, a more holistic catchment-wide assessment of ecosystem health can be obtained.
Objectives
O1. Quantify the long-term impacts of (1) episodic CSOs and other point-source, and (2) non-point discharges on environmental condition, and aquatic macrophyte, macroinvertebrate and fish communities in river and floodplain habitats.
O2. Examine the impact of new wastewater management practices (aimed at improving water quality by reducing CSOs and other point-source discharges), on environmental condition, and patterns of recovery by aquatic macrophyte, macroinvertebrate and fish communities in river and floodplain habitats.
O3. Determine the effects of water quality improvement on river ecosystem functioning, by comparing decomposition rates between managed, unmanaged and reference river catchments.
O4. Use data from O1 to O3 to develop catchment-scale management and conservation recommendations to enhance freshwater biodiversity which can be widely applied across the UK.
Methods
Long-term environmental and ecological datasets (1980s-present) will be examined to quantify the long-term impacts of CSO and other point-source discharges, and non-point discharges, on freshwater biodiversity across rivers in the New Foret (01). To quantify the effect of future wastewater management changes on freshwater communities and ecosystem functioning (02 and 03), seasonal sampling of aquatic macroinvertebrates, macrophytes, fish, and decomposition will be undertaken for at least 3 years. Fieldwork will focus on the Beaulieu, Lymington and Dark Water Rivers, as different stretches of these rivers are subject to different stressors, and can be subdivided as (i) no anthropogenic input, (ii) CSO and other point discharges only, and (iii) surface runoff pollution (non-point sources). In addition, the timing of CSO discharge mitigation works at different sites on these rivers will vary within the timeframe for data collection, allowing assessment of temporal change to physical and ecological parameters. Alongside the main river channels, environmental and ecological sampling will also occur in corresponding freshwater floodplain habitats (ponds and wetlands). Aquatic macroinvertebrate [13,14], macrophyte [15] and fish [16] communities will be sampled following standard methodological procedures. Environmental data collection will include a suite of water chemistry parameters, physical habitat, and spatial parameters. Decomposition will be measured using standardised cotton strips, which will be placed in sample sites for different lengths of time each season (21, 37, 50 days). Cotton strip tensile strength will be quantified and used as a proxy for decomposition.
Outcomes
The project is highly novel and timely, given there is a critical need to understand the long-term impacts of water pollution at a multi-habitat scale (most previous research has focussed pollution impacts within a single habitat type), and how wastewater infrastructure and management changes may influence freshwater communities across different trophic levels (previous studies focus on single faunal and floral groups). A consideration of ecosystem functioning (decomposition) alongside biodiversity, will ensure that the effects of new wastewater management practices on overall ecosystem health can be quantified, and the conclusions of this PhD will establish holistic catchment-wide management recommendations. This project will be collaborating with several organisations (Southern Water, FHT, Wild New Forest) and will encourage local community engagement with the project. Given the multi-habitat and large-scale approach to assessing the ecological effects of wastewater management practices, this work will result in at least four scientific publications.
View full project description (pdf 236kb)
The closing date is 30 June 2024
