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Cambridge NERC Doctoral Training Partnerships

Graduate Research Opportunities

Lead supervisor: David Aldridge, Zoology

Co-supervisor: Ed Turner, Zoology

Brief summary: 
This project will investigate spatial and temporal patterns of parasites within native and invasive freshwater snails to develop and test fundamental concepts in host-parasite relationships. The effects of parasites on conservation and behaviour can be studied.
Importance of the area of research concerned: 
Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail–trematode interactions. However, surprisingly little attention has been paid to the effect of trematodes, and other parasites, on the ecology and conservation of gastropods in temperate regions. Moreover, the introduction of invasive non-native gastropods (e.g. New Zealand mudsnail, Chinese mystery snail) presents the potential for the introduction of novel parasites to native gastropods, and the possible purging of parasite load from the invader (Enemy Release) resulting in greater potential for spread and impact. Trematodes also affect host behaviour, increasing the likelihood of predation by definitive hosts. This project offers the opportunity for investigating a novel study system, combining field-based surveys with laboratory experiments, to develop and test concepts that may be of both specific importance to gastropod conservation, but also serve as a model for understanding broader host-parasite dynamics.
Project summary : 
Recent studies by the group have shown that trematode parasites in UK freshwater bivalves can castrate their host, halting reproductive output. We have also found trematodes and other parasites in a number of gastropod species (e.g. Viviparus viviparus), although the parasites' distribution, abundance and effects remain to be studied. Gastropods are important ecosystem engineers, grazing biofilms, regulating plant growth and affecting sediment structure. Parasites may play an important role in mediating important ecosystem effects and may also play a previously overlooked role in driving declines in endangered gastropod species. The interactions between different parasites within a single host open up opportunities for investigation of drivers of community structure. Studying invasive snails offers opportunities for investigating concepts such as 'spillover' and 'enemy release'.
What will the student do?: 
Initially, studies will involve field-based collections and laboratory dissections to understand spatial and temporal patterns in parasite loads. Field-based observations will lead-on to the development and testing of hypotheses through laboratory manipulations and further field work. The student may wish to develop ideas in either the direction of ecological engineering and conservation, or host-parasite models, or both. Large populations of Viviparus viviparus are readily available to sample from rivers close to Cambridge. Invasive populations of New Zealand mudsnails are available in the River Thames, and Chinese mystery snails have recently established in the Pevensey Levels. There are opportunities in the laboratory for experimentally manipulating the trematode load within snails. Behavioural studies of infected and uninfected snails could be conducted and the ecological and conservation implications assessed.
References - references should provide further reading about the project: 
Brian, J.I. & Aldridge, D.C. 2019. Endosymbionts: An overlooked threat in the conservation of freshwater mussels? Biological Conservation, vol. 237, pp. 155-165.
Brian, J. I. & Aldridge, D. C. 2021. Abundance data applied to a novel model invertebrate host shed new light on parasite community assembly in nature. Journal of Animal Ecology, vol. 90, pp. 1096-1108.
Fredensborg, B. L. & Poulin, R. J. 2006. Parasitism shaping host life-history evolution: adaptive responses in a marine gastropod to infection by trematodes. Journal of Animal Ecology, vol. 75, pp. 44-53.
You can find out about applying for this project on the Department of Zoology page.