The unique feeding mechanism of parrotfishes plays crucial ecological roles in tropical coral reefs. By scraping and excavating the substrate, parrotfishes disturb benthic communities, remove calcareous layers of the reef and contribute to the formation, reworking and transport of sediments. Although previously considered generalist herbivores, new evidence regards parrotfishes as “microphages” which target epilithic and endolithic microorganisms colonising the substrate. These organisms, predominantly cyanobacteria, provide a protein-rich nutritional source and, therefore, represent a principal dietary target for some parrotfish species.
My Masters by Research will explore the intricacies of parrotfish feeding in the context of nutrient enrichment from seabird guano deposits. I aim to study parrotfish feeding rates, dietary targets and substrate preferences across nutrient gradients in the Seychelles. The project will involve observations of parrotfish feeding and microhistology analyses of core samples from reef substrata.
Seabird-derived nutrients from breeding colonies leach to surrounding reefs and mediate patterns in primary production. An enhanced availability of photoautotrophs, particularly microbes, may have implications for parrotfish feeding, and consequently, the ecological functions performed by this diverse and abundant group of fish.
The introduction of invasive species to island ecosystems poses an major threat to biodiversity. For example, the loss of breeding seabird colonies as a result of rat infestations has cascading effects which alter productivity and functioning on nearby coral reefs. Invasive species eradication, ecological restoration and reinvasion prevention remain challenging, however, should be considered a conservation priority.