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The extended ecology of the Sharknose Goby Cleaner Fish

Whittey, Kathryn 2021. The extended ecology of the Sharknose Goby Cleaner Fish. PhD Thesis, Cardiff University.
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Far from being specialised occurrences, symbiotic relationships including mutualisms, are ubiquitous. The coral reef ecosystem is the product of a mutualistic symbiosis between corals and their endosymbiotic zooxanthellae. The coral polyp creates a sheltered space for the zooxanthellae, while the zooxanthellae provide nutrients to the host through photosynthetic activity. This mutualism has allowed a diverse range of coral animals to evolve and together multiple species of corals create a highly complex 3-dimensional habitat. The plethora of available habitat space has facilitated the evolution of multiple species and, as such, coral reefs are one of the most biodiverse habitats on Earth. In addition, the diversity on coral reefs has facilitated the evolution of a multitude of behavioural niches. Cleaner fish mutualisms are perhaps one of the best-studied interactions on coral reefs. However, the role that the coral habitat plays in facilitating the cleaner-client mutualism is often overlooked and how specific habitat traits affect cleaning behaviour is unknown. This thesis firstly, quantifies the structural components of the cleaner fish’s (Elacatinus evelynae) coral habitat and demonstrates that cleaners more frequently inhabit tall corals and that structural complexity increases cleaning interactions (Chapter 2). Unfortunately, due to anthropogenic global change, coral habitat is threatened and corals are disappearing. It is therefore timely that we discover what important attributes corals may contribute to marine inhabitants. Further to this, since the extent of the loss is so vast, multiple studies have sought to artificially replicate coral structure. Although artificial reefs are being widely deployed it is not fully understood how fish respond to these artificial structures at an individual level. Thus, this thesis investigates the behavioural interactions of fish species with novel artificial structures, finding that damselfish associate with artificial structures more than natural corals, potentially due to the increased space available for algae farming (Chapter 3). In addition to the structural element, corals harbour microbial communities that are also threatened by global change. Commensal microbial communities are integral to host health, yet there is little known about these communities in wildlife populations. Fish harbour a diverse microbiota on their skin, and this mucosal layer is in constant contact with organisms in the marine environment; as such it is possible that microbes may be shared between closely interacting individuals. This is particularly relevant to the sharknose goby (E. evelynae), which spends the majority of its time in direct contact with the coral cleaner station. Therefore, the microbial communities of the sharknose goby and its habitat were characterized and intriguingly, cleaners share bacterial genera with Palythoa caribaeorum, a common but toxicbenthic constituent of cleaner fish stations (Chapter 4). Finally, to further knowledge of microbial communities of the sharknose goby, the gut and skin communities are described and using microbial gene predictions several genes associated with toxicity in other fish species are identified (Chapter 5). In summary, this thesis investigates a range of species interactions at multiple scales, from fish and coral habitat interactions to the association of fish with coral bacteria. This thesis furthers our knowledge of how individual fish respond to artificial reefs and demonstrates key aspects of E. evelynae ecology.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Date of First Compliant Deposit: 31 May 2022
Date of Acceptance: 30 May 2022
Last Modified: 31 May 2022 09:55

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