Effects of parasites on food web structure and dynamics: new ways to improve accuracy and ecological realism [SUPER Doctoral Training Partnership (DTP)]

3.5-year NERC Studentship awarded to the SUPER Doctoral Training Partnership

Food webs are central to fundamental aspects of ecology, including complexity, diversity, stability and functioning¹ and powerful tools for the management of complex ecosystems² and fisheries³. Even though parasitism is the most common consumer strategy in the animal kingdom and parasites can be involved in >50% of interactions in trophic networks⁴, they have been ignored in food webs until recently. It reflects the common, but often mistaken, assumption that parasites contribute little to the energy flow in an ecosystem⁵. Parasites can augment and redirect the flow of energy in an ecosystem through the modification of their hosts’ behaviour and productivity is high in parasites since they circumvent metabolically expensive activities such as movement and homeostasis and parasite biomass can even exceed that of top predators in some ecosystems⁶.

Food webs are commonly used to study the resilience of an ecosystem to species loss and other perturbations. Parasite inclusion amplifies complexity and initially increases food web robustness, due to apparently functional redundancy in parasites. However, the life cycles of most parasites include multiple life stages that undergo diet and niche changes that are not accounted for, which exemplifies the need for more accurate methods of parasite inclusion to improve ecological realism in food web ecology.

We are interested in three types of food webs:

1) topological webs representing feeding interactions between species, illustrated by a binary matrix, in which each species (or node) acts as both consumer and resource.

2) energetic food webs that include information on the biomass of each species and represent more accurately the flow of energy in an ecosystem.

3) functional food webs including links representing the effect of each species on another’s population growth.

This studentship provides a fantastic opportunity to contribute to the understanding of how parasites affect food web structures and dynamics in commercially important marine fish species in Scottish waters. With e.g. herring being a key species in food webs of West Coast Scottish waters, recent declines in stocks can result in significant knock on effects of the food web structure and dynamic. Parasites could have an elevated impact on the remaining populations in the ecosystem making long-term recovery of affected stocks more difficult. Ecosystem health and the ability for recovery are crucial to maintain the integrity of food web structures from coast to sea.

Consequently, understanding the role parasites play in marine food webs and ecosystems is a fundamental, but underestimated and understudied aspect of fisheries management around the Scottish coastal zone.

You will gain skills/expertise in

• boat-based fish sampling
• fish dissection and parasite identification
• analysing water samples for eDNA; marker/primer selection, PCR-amplification, DNA library preparation; use of bioinformatic algorithms to extract information from the sequence-data 
• comparing literature, actual parasite data and eDNA results for parasite occurrence in relevant food webs
• developing new parasite inclusion methods and models
• comparing their effects with existing methods on food web topology and structure, as well as energy flow

You will be based at Edinburgh Napier University, with frequent visits to University of Strathclyde in Glasgow, where Dr Speirs is based, and visits to Marine Scotland Science in Aberdeen to meet with Dr Pert. You will be part of a thriving PhD community and supportive environment. 

As a SUPER DTP student, you will benefit from inter-institutional input and shared training from 8 Scottish Universities, supported by our Graduate School and Postgraduate Professional Researcher Development Certificate (PG Cert.), to develop skills in communication, team-working and management in addition to your research skills. There will be numerous opportunities to present at conferences. Through the PhD partnership network and your gained skill set, you will have an excellent employment potential across a range of different environments/disciplines and sectors (e.g. academic, industry, regulatory).

Academic qualifications

A first (at least a 2.1), or Master’s degree (or equivalent) ideally in a relevant field such as parasitology, marine biology/ecology, fisheries biology, environmental biology.

Essential attributes:

• Strong motivation, with evidence of independent research skills relevant to the project
• Fundamental laboratory skills,
• Strong interest in parasitology
• Competency in data analysis, ‘R’
• Good communication skills, time management

Desirable attributes:

• Good knowledge of, strong interest in aquatic biology, taxonomy, food web ecology
• Fish dissection, parasite isolation and identification skills
• Modelling experience
• Sea-worthiness for fish sampling

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The start date of this project is: 27 September 2021