Habitat degradation modifies the strength of interspecific competition in coral dwelling damselfishes

Boström-Einarsson, Lisa, Bonin, Mary C., Munday, Philip L., and Jones, Geoffrey P. (2014) Habitat degradation modifies the strength of interspecific competition in coral dwelling damselfishes. Ecology, 95 (11). pp. 3056-3067.

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Habitat degradation is predicted to exacerbate competition for critical resources; however, the relationship between habitat quality and competition is poorly understood. In this study, we used a manipulative experiment to test the effects of habitat degradation on competition between two planktivorous, coral-dwelling damselfishes, Chrysiptera parasema and Dascyllus melanurus. Experimental reefs were constructed with either healthy (100% live) or degraded (10% live) Acropora longicyathus coral, stocked with varying densities of these two fish species, and monitored for two months. On healthy habitat, the mortality of C. parasema was density dependent, and increased substantially in the presence of the dominant interspecific competitor D. melanurus. In contrast, on reefs where habitat was degraded, C. parasema mortality was highly variable, density independent, and was no longer influenced by the presence of dominant competitor D. melanurus. Behavioral observations revealed that agonistic interactions for both species increased with density on degraded habitat, but not on healthy habitat. In addition, on degraded reefs, both species displayed a reduced association with reef habitat and ventured further away from shelter with increasing densities of the dominant competitor D. melanurus. These results suggest that reduced habitat quality can have such a profound effect on reef fishes, that it eliminates density-dependent mortality and competitive dominance hierarchies, thereby substantially altering the mechanisms that structure reef fish communities.

Item ID: 37034
Item Type: Article (Research - C1)
ISSN: 1939-9170
Keywords: agonistic behavior, Chrysiptera parasema, coral reef fishes, damselfish, Dascyllus melanurus, density dependence, habitat degradation, habitat loss, interspecific competition, intraspecific competition
Funders: Australian Research Council (ARC), College of Marine and Environmental Sciences, James Cook University, Center of Excellence for Coral Reef Studies
Date Deposited: 07 Jan 2015 07:45
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 40%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060202 Community Ecology (excl Invasive Species Ecology) @ 30%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 40%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 60%
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