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Glenn is Associate Professor in the School of Natural Sciences and is Co-Principal of the Centre for Marine Ecosystems Research.
Understanding the roles of coastal habitats in contributing and maintaining biodiversity is fundamental to our ecological knowledge and management practices. My research attempts to address both fundamental ecological and applied issues, focusing predominantly on two major themes: (1) understanding the interactions of organisms in the marine and estuarine environment, particularly the pathways of connectivity across ecosystems in coastal landscapes; and (2) understanding the role of coastal habitats including seagrasses and estuaries for fish.
Considerable focus has been placed on the importance of cross-boundary movement of material in recent years, but much of that focus has been directed towards movement of nutrients via seabirds to islands and wrack onto beaches and in surf zones. There is limited knowledge on the value of this type of movement in other systems such as seagrass. To gain a better understanding of this type of interaction, I adopt approaches using biomarkers, including stable isotopes and fatty acids, and experimental manipulations. Understanding the relative importance of different types of macrophytes and the pathways that lead to spatial subsidies is a critical aspect of landscape ecology and marine management.
Understanding how consumers interact with food resources, and therefore, ecosystem structure is important for effective management of ecosystems through marine protected areas or resource extraction. For example, while the fishery for western rock lobster is the most valuable single-species fishery in Australia and has been awarded Marine Stewardship accreditation for its environmental sustainability, little was known about the fishery’s impact on the ecosystem. Recent work has shown that, under present day densities, there is no detectable influence by this consumer on the benthic ecosystem. Studies on rates of herbivory in the coral-reef system at Ningaloo Reef have shown high spatial variability in the abundances and grazing rates of herbivorous fish species. This variability needs to be considered when using marine protected areas as a management tool.
Seagrass meadows, like many other coastal habitats with relatively high structural complexity (e.g. reefs and mangroves), can strongly influence fish assemblages in coastal regions. This generalization has emerged from a large number of studies that have shown greater diversity and density of fish in seagrass meadows compared to bare sand areas. My research has indicated that these patterns are far less convincing for fish in meadows of Posidonia and Amphibolis species, with meadows comprising different dominant seagrass species displaying different patterns when compared to bare sand areas, and meadows are dominated by species that spend their entire lifecycle in those habitats. Other research has focused on understanding the structure of fish assemblages in a range of other coastal habitats such as estuaries, surf zones.