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Marine Ecology Progress Series

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MEPS 439:203-212 (2011)  -  DOI:

Elevated size and body condition and altered feeding ecology of the grouper Cephalopholis argus in non-native habitats

Amanda L. Meyer1,2,*, Jan Dierking1,3,*,**

1Department of Zoology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
2Present address: Pacific Reefs National Wildlife Complex, US Fish and Wildlife Service, Honolulu, Hawaii 96850, USA
3Present address: Leibniz Institute of Marine Sciences (IFM-GEOMAR), Evolutionary Ecology of Marine Fishes Group,
24105 Kiel, Germany
*The 2 authors contributed equally to this study

ABSTRACT: In 1956, the shallow-water grouper Cephalopholis argus was introduced from Moorea (French Polynesia), where grouper diversity (14 species) is high, to the Main Hawaiian Islands (MHI), where only 2 rare native deep-water groupers occur. In this non-native environment, the species has flourished and has become the dominant apex predator on many reefs. In the present study, a comparison of non-native populations of C. argus in the MHI with native populations in Moorea showed that mean total length (32.0 vs. 26.9 cm), mass (722 vs. 326 g), growth, and body condition were each significantly elevated in the MHI. In addition, while an ontogenetic shift towards larger prey occurred in both locations, it was faster and more consistent in Moorea than in the MHI. As a result, while small C. argus of comparable size in the 2 locations consumed similar-sized prey, large C. argus in Moorea consumed significantly longer and deeper-bodied prey than their counterparts in the MHI. This pattern was unrelated to the size distributions of available prey and may thus reflect stronger intra- and interspecific competition for small prey in Moorea. Although ecological release in a broader sense (i.e. a combination of predator release, parasite release, and competitive release) may play a role, the most direct explanation for the observed differences between C. argus in native habitats in Moorea (with many competing grouper species) and non-native habitats in the MHI (few competitors) would be competitive release (here used in the sense of benefits resulting from the reduction of interspecific competition).

KEY WORDS: Competitive release · Ecological release · Interspecific competition · Niche shift · Invasive species · Peacock hind · Main Hawaiian Islands · Moorea (French Polynesia)

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Cite this article as: Meyer AL, Dierking J (2011) Elevated size and body condition and altered feeding ecology of the grouper Cephalopholis argus in non-native habitats. Mar Ecol Prog Ser 439:203-212.

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