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Duke University

Publication Date

Spring 2015

Program Name

Australia: Rainforest, Reef, and Cultural Ecology


This study examines the use of sub-tidal open-bottom, rocky, and seagreass habitats by the Siganus genus (herbivores), Gerres genus (benthivores), and planktivores in the Hinchinbrook Channel Estuary in Queensland, Australia. The Hinchinbrook Channel Estuary, a tropical estuary cutting between Hinchinbrook Island and the Australian mainland, is surrounded primarily by mangroves. Its sub-tidal habitats are largely unexplored due to factors such as low visibility and the presence of estuarine crocodiles. In this study, I reviewed 699 underwater videos collected by James Cook University PhD candidate Michael Bradley in order to analyze feeding and movement behavior of pre-identified fish.

The results of this study show that Siganids feed mostly in seagrass areas but are often present in rocky areas, potentially using the rocky structures as protection and refuge. Gerres also feed mostly in seagrass areas but also feed in open-bottom areas, which suggests that while seagrass areas are important, even habitats that appear barren provide service to certain fish. I observed Gerres searching on the benthos in all habitats but did not see them feed in rocky habitats, and they were seldom sighted there. Planktivores, on the other hand, feed most often in rocky habitats and also feed occasionally in the other two habitats, suggesting a need to apply conservation efforts to all of these sub-tidal habitats. The videos revealed site-attached behavior (when fish remain in the same area for an extended period of time) mostly in rocky areas yet at least some site attachment in all of the habitats, again suggesting that all hold some importance for fish.

Understanding the use of sub-tidal habitats by these particular groups of fish is important, as they all are connected to other habitats like coral reefs through their movement and feeding, and thus the habitats studied affect these other ecosystems. Understanding these connections can help inform management techniques to maintain maximum connectivity and increase resilience of the ecosystems. I recommend management techniques including stringent fishing and recreation rules in the Hinchinbrook Channel and a reduction in agricultural chemicals used in the surrounding areas. I also recommend further research on other habitats and fish species in the estuary and similar research in other estuaries.


Animal Studies | Aquaculture and Fisheries | Asian Studies | Environmental Studies | Marine Biology | Pharmacology, Toxicology and Environmental Health | Systems Biology | Zoology


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