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Faunal composition within algal mats and adjacent habitats on Likuri Island, Fiji Islands

Published online by Cambridge University Press:  17 November 2008

Andrea C. Alfaro*
School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1020, New Zealand
W. Lindsey Zemke-White
School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1020, New Zealand
Winifereti Nainoca
School of General Studies, Fiji Institute of Technology, Samabula Campus, Suva, Fiji Islands
Correspondence should be addressed to: A.C. Alfaro, School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1020, New Zealand email:


The faunal composition within three mono-specific algal habitats was investigated at Likuri Island, southern Viti Levu, Fiji Islands. Gracilaria maramae was the dominant alga within algal drift mat, seagrass bed, and rocky substrate habitats at the study site. This algal species exhibits two distinctive morphologies depending on whether it is attached or loose-lying. When attached to seagrass blades or rocky substrates, this alga has long straight branches stemming from a single holdfast, while detached individuals develop curled tendrils that re-attach to adjacent substrates. Re-attachment behaviour and high growth rates result in a dense mat of drift algae, which provides a suitable micro-habitat for macro-invertebrates. The sources of algal fragments that contribute to the algal mat appear to be nearby seagrass beds and rocky substrates, where this species may settle directly from spores. Storm events may detach these algae, although pulling experiments showed that the attachment to rocky substrates is 5 times stronger than the attachment to seagrass blades. Results from the macro-faunal samples indicate that the loose-lying algal mat habitat had the highest abundance and biodiversity of organisms, followed by the seagrass bed, and then the rocky substrate habitat. The ability of loose G. maramae fragments to re-attach, along with their high growth rate, may provide a unique micro-habitat for highly abundant and diverse faunal assemblages, which in turn may sustain adjacent near-shore communities. This study highlights the ecological importance of floating algal mats to coastal ecosystems, which should be considered in future management strategies throughout the Fiji Islands.

Research Article
Copyright © Marine Biological Association of the United Kingdom 2008

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