The impact of bottom trawling on seabed ecosystem functioning

Marine sediments harbour significant levels of biodiversity that play a key role in ecosystem functions and services such as biogeochemical cycling, carbon storage and the regulation of climate. Mobile bottom fisheries constitute the most widespread physical disturbance to seabed habitats. The disturbance of surface sediments enhances mixing and resuspension and causes shifts in faunal assemblage. By depleting fauna and changing the species composition, bottom fishing may result in alterations in the functional traits (bioturbation, bioirrigation) of a community, which in turn has broad implications for the overall ecosystem performance. An improved understanding of the link between species functional traits and proxies of processes for specific ecosystem functions, and the influence of bottom trawling on these relationships is important to improve our ability to predict the impact of fishing disturbance on benthic ecosystem functioning more accurately. This PhD provides an opportunity for important research to be undertaken to build a more concrete knowledge base on the ways fisheries interact with global biogeochemical cycles.

The PhD will use a combination of meta-analysis, numerical and biogeochemical modelling techniques to examine the influence of trawling on benthic species functional traits and the biogeochemical process rates (e.g. oxygen consumption and nutrient fluxes) that drive key ecosystem functions such as the cycling of organic matter (carbon and nutrient). This PhD is primarily desk-based and will make use of existing spatiotemporal datasets of benthic faunal, geochemical and physical data from the North Sea. The student will have the opportunity to develop skills in trait-based approaches, biogeochemical modelling and evidence synthesis tools, as well as develop science communication skills through participation in international or national conferences, and presentation of research during seminars held at Heriot-Watt university, Bangor University, Royal Netherlands Institute for Sea Research (NIOZ) and Centre for Environment Fisheries and Aquaculture Science (CEFAS). There will also be an opportunity to participate in the ICES working group on Fisheries Benthic Impacts and Trade-offs (WG FBIT) that brings together a multidisciplinary group of scientists from more than 15 countries to advance assessment methods of trawling impacts on benthic marine communities and their functioning.

 

Funding

This is a full scholarship, funded by Heriot-Watt University for 3.5 years and covers the PhD tuition fees and stipend (currently £19,237 per annum). Full funding is available to UK, EU and international students.

 

Eligibility

Required qualifications:

• First-class honours degree or a 2.1 honours degree plus Masters (or equivalent) in marine biology, biogeochemistry, quantitative ecology, biological oceanography or in a related field,
• Skills in analyses of large data sets (time-series and spatial analyses, statistical modelling) and/or experience of biogeochemical modelling,
• Experience with statistical software such as R,
• Enthusiasm for working in an international and interdisciplinary team,
• A high level of proficiency in written and spoken English.

Merits:

• Knowledge in community ecology, biodiversity, trait-based approaches, functional ecology, benthic ecology and biogeochemistry,
• Knowledge in ecological statistics, multivariate statistics, nonlinear models, meta-analysis, quantitative data analysis, applied mathematics,
• Ability to work independently to solve problems,
• Capacity to interact well in a research group (i.e. team work),
• Capacity to be creative and organized.

 

Supervisory team

The student will be based at the Lyell Centre under the supervision of Dr Marija Sciberras but will work closely with Prof Karline Soetaert (NIOZ), Prof Jan Hiddink (Bangor University) and Dr Clement Garcia (CEFAS). The team brings expertise in impacts of anthropogenic stressors on marine benthic ecosystem functioning, systematic review, meta-analytical analysis, environmental and biogeochemical modelling. All are based in research-active departments that span a broad range of ecological, environmental and geochemical research, exposing the research student to a range of research areas. The student will be required to undertake periodic research visits to work with co-supervisors at NIOZ and at CEFAS.

 

How to apply

Applicants are requested to send a cover letter stating why they are interested in the PhD, what ideas you could bring to the project, and outline any relevant experience. Please also submit a CV with all qualifications to date. The cover letter and CV should be sent to Dr Marija Sciberras (m.sciberras@hw.ac.uk). Candidates are invited to contact Dr Sciberras for an informal chat about the project.

In addition, to apply you must complete our online application form via the Heriot-Watt University website.

Please select PhD Marine Biology as the programme and include the full project title, reference number and supervisor name (Dr M Sciberras) on your application form. Ensure that all fields marked as ‘required’ are complete.

Once have entered your personal details, click submit. You will be asked to upload your supporting documents. You must complete the section marked project proposal; provide a supporting statement (1-2 A4 pages) documenting your reasons for applying to this particular project, why you are an ideal candidate for the position and what ideas you could bring to the project. 

You must also upload your CV, a copy of your degree certificate and relevant transcripts and an academic reference in the relevant section of the application form. 

You must also provide proof of your ability in the English language (if English is not your mother tongue or if you have not already studied for a degree that was taught in English within the last 2 years). We require an IELTS certificate showing an overall score of at least 6.5 with no component scoring less than 6.0 or a TOEFL certificate with a minimum score of 90 points.

Please contact egis-pgr-apps@hw.ac.uk for technical support with your application.

 

Time-lines

The closing date for applications is 27 May 2024. Applicants must be available to start the PhD in September 2024.

 

Reading List

Beauchard O, Thompson MSA, Ellingsen KE, Piet G, Laffargue P, Soetart K. 2023. Assessing sea floor functional biodiversity and vulnerability. Marine Ecology Progress Series. doi: https://doi.org/10.3354/meps14270
De Borger E, Tiano J, Braeckman U, Rijnsdorp AD, Soetaert K. 2021. Impact of bottom trawling on sediment biogeochemistry: a modelling approach. Biogeosciences. doi.org/10.5194/bg-18-2539-2021
Hiddink JG, Jennings S, Sciberras M, et al. 2018. Assessing bottom-trawling impacts based on the longevity of benthic invertebrates. Journal of Applied Ecology. doi.org/10.1111/1365-2664.13278
Sciberras M, Hiddink JG, Jennings S, et al. 2018. Response of benthic fauna to experimental bottom fishing: a global meta-analysis. Fish and Fisheries. doi.org/10.1111/faf.12283
Toussaint E, De Borger E. Braeckman U et al. 2021. Faunal and environmental drivers of carbon and nitrogen cycling along a permeability gradient in shallow North Sea sediments. Science of the Total Environment. doi.org/10.1016/j.scitotenv.2021.144994