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Tracing an Invasion Paradox across Scales: Patterns and Tests for the Effects of the Introduced Predatory Grouper, Roi (Cephalopholis argus) in Hawai‘i.

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Title:Tracing an Invasion Paradox across Scales: Patterns and Tests for the Effects of the Introduced Predatory Grouper, Roi (Cephalopholis argus) in Hawai‘i.
Authors:Giddens, Jonatha L.
Contributors:Zoology (department)
Date Issued:May 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Theory, observation, and experimental studies in invasion ecology have led to
what is known as the ‘invasion paradox’, where both the factors that determine the
invasability of ecosystems, and the invasiveness of species are context specific. As the
patterns observed and the underlying processes are sensitive to the extent and resolution
of inquiry, paradox can best be understood by tracing patterns and processes across
scales. In Hawai‘i, a mid-sized predatory grouper, roi (Cephalopholis argus) was
introduced during the 1950s, and subsequently established and spread throughout the
main archipelago. Yet, the seascape factors that drive their distribution, a determination
of their impact on the native reef fish assemblage, and methods for assessing and
managing roi populations, were previously unknown. To address this gap in knowledge, I
conducted studies of roi in Hawai‘i at three levels of organization: 1) field observations at
the population level; 2) field manipulative experiments at the community level; and 3)
species distribution modeling at the seascape level. I trace salient factors of roi
invasiveness and community invasability across the three scales, and relate these to the
human social system, as the roi introduction effects, and is affected by human
communities. I found that with low population mortality rates, introduced roi has the
potential to be an effective invader. Yet, over a long-term predator removal experiment,
roi had no effect on the abundance of their prey. Likewise, in the seascape context,
populations of roi declined in relation to increasing densities of native fish species. In the
broadest sense, this introduced species has inspired community-led conservation action in
Hawai‘i through roi fishing tournaments and thus, roi present an opportunity to engage
across sectors and strengthen collaborative ocean management.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017.
URI:http://hdl.handle.net/10125/62828
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Zoology


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