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From parasitism to mutualism: exploring the role of ectoparasitism in determining the distribution, health and survival of juvenile coral reef fishes

Supervisor: Professor Andrea Manica

Project summary:

A key ambition of ecological research is to understand the processes that shape the distribution of species through time and space. Antagonistic interactions, such as those between predators or parasites and their prey, are ecologically important and present tractable model systems to explore how natural selection can shape the distribution of biodiversity from a local to global scale (Feeney et al. 2018).

The recruitment phase of most juvenile coral reef fish life-cycles presents a particularly interesting opportunity to study the role that antagonistic interactions play in determining the distribution of biodiversity, given that recruiting coral reef fishes face a "predation gauntlet" as they recruit from their pelagic larval to sedentary juvenile life-history stage (Almany & Webster 2006; Goatley & Bellwood 2016) and also face substantial micropredation threats from ectoparasitic gnathiid isopods (Sellers et al. 2018). Previously, substantial research efforts have investigated the role that cleanerfishes play in mitigating the detrimental effects of gnathiids on reef fishes (Grutter 1999); however, the role that habitat selection plays in mitigating their effects, especially in newly recruited fishes, remains largely unknown. 

What the student will be doing:

Using a combination of behavioural observations, aquaria and field experiments and molecular analyses, we will investigate how the risk of ectoparasitism and micropredation by gnathiids influences settlement decisions by juvenile fishes, as well as the broader consequences of gnathiid-fish interactions for the structure and composition of coral reef fish communities.


Almany & Webster (2006) Coral Reefs 25: 19-25; Feeney et al.

(2018) Ecol. Lett.; Goatley & Bellwood (2016) 283: 20161858; Grutter (1999) Nature 398: 672-673; Sellers et al. (2018) Oecologia.


This project falls within the remit for our Claire Barnes studentship in Marine Biology