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The role of gaping behaviour in habitat partitioning between coexisting intertidal mussels

Nicastro, K, Zardi, G, McQuaid, C, Stephens, L, Radloff, S and Blatch, Gregory L (2010) The role of gaping behaviour in habitat partitioning between coexisting intertidal mussels. BMC Ecology, 10. pp. 1-11. ISSN 1472-6785 (print) 1472-6785 (online)

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Background Environmental heterogeneity plays a major role in invasion and coexistence dynamics. Habitat segregation between introduced species and their native competitors is usually described in terms of different physiological and behavioural abilities. However little attention has been paid to the effects of behaviour in habitat partitioning among invertebrates, partially because their behavioural repertoires, especially marine benthic taxa, are extremely limited. This study investigates the effect of gaping behaviour on habitat segregation of the two dominant mussel species living in South Africa, the invasive Mytilus galloprovincialis and the indigenous Perna perna. These two species show partial habitat segregation on the south coast of South Africa, the lower and upper areas of the mussel zone are dominated by P. perna and M. galloprovincialis respectively, with overlap in the middle zone. During emergence, intertidal mussels will either keep the valves closed, minimizing water loss and undergoing anaerobic metabolism, or will periodically open the valves maintaining a more efficient aerobic metabolism but increasing the risk of desiccation. Results Our results show that, when air exposed, the two species adopt clearly different behaviours. M. galloprovincialis keeps the shell valves closed, while P. perna periodically gapes. Gaping behaviour increased water loss in the indigenous species, and consequently the risk of desiccation. The indigenous species expressed significantly higher levels of stress protein (Hsp70) than M. galloprovincialis under field conditions and suffered significantly higher mortality rates when exposed to air in the laboratory. In general, no intra-specific differences were observed in relation to intertidal height. The absence of gaping minimises water loss but exposes the invasive species to other stresses, probably related to anoxic respiration. Conclusions Gaping affects tolerance to desiccation, thus influencing the vertical zonation of the two species. Valve closure exposes the invasive species to higher stress and associated energy demands, but it minimizes water loss, allowing this species to dominate the upper mussel zone, where the gaping indigenous P. perna cannot survive. Thus even very simple behaviour can influence the outcome of interactions between indigenous and invasive species.

Item Type: Article
Uncontrolled Keywords: ResPubID22185, environmental heterogeneity, species, Mytilus galloprovincialis, Perna perna, dehydration, stress, gaping behaviour
Subjects: Historical > Faculty/School/Research Centre/Department > School of Biomedical and Health Sciences
Current > FOR Classification > 0602 Ecology
Current > FOR Classification > 0605 Microbiology
Depositing User: VUIR
Date Deposited: 12 Jul 2012 02:29
Last Modified: 12 Jul 2012 02:29
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Citations in Scopus: 45 - View on Scopus

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