Comparison of phototrophic shell-degrading endoliths in invasive and native populations of the intertidal mussel Mytilus galloprovincialis

Marquet, Nathalie; Nicastro, Katy R; Gektidis, M.; McQuaid, C. D.; Pearson, G. A.; Serrão, Ester; I Zardi, Gerardo

http://hdl.handle.net/10400.1/4097

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Abstract(s)

The intertidal mussel Mytilus galloprovincialis is a successful invader worldwide. Since its accidental introduction onto the South African west coast in the late 1970s, it has become the most successful marine invasive species in South Africa. One possible explanation for this phenomenon is that M. galloprovincialis suffers less from phototrophic shell-degrading endoliths in its invasive than in its native range. We assessed photoautotrophic endolithic pressure on M. galloprovincialis in native (Portugal) and invasive (South Africa) ranges. Invasive populations were more heavily infested than native populations. In Portugal, only the biggest/oldest mussels displayed endolithic erosion of the shell and the incidence of infestation was greater at higher shore levels where more prolonged exposure to light enhances endolith photosynthesis. In South Africa, even the smallest size classes of mussels were heavily infested throughout the shore. In Portugal, endolithicinduced mortality was observed at only one location, while in South Africa it occurred at all locations and at significantly higher rates than in Portugal. Important sub-lethal effects were detected in infested native mussels, confirming previous studies of invasive populations and suggesting an energy trade-off between shell repair and other physiological constraints. We observed a positive relationship between infestation rates and barnacle colonization on mussel shells, suggesting possible facilitation of barnacle settlement/survival by shell-boring pathogens. Identification of endoliths revealed common species between regions. However, two species were unique in the invasive range while another was unique in the native region. Different levels of endolithic infestation in the invasive and the native range were not explained by the effect of major environmental determinants (Photosynthetically Available Radiation and wave height). The results reject our initial hypothesis, indicating that invasion success of M. galloprovincialis is not simply explained by escape from its natural enemies but results from complex interactions between characteristics of the invaded community and properties of the invader.

Keywords

Marine invasion Endoliths Parasitism Bioerosion

URI

http://hdl.handle.net/10400.1/4097

Citation

Marquet, N.; Nicastro, K.R.; Gektidis, M.; McQuaid, C.D.; Pearson, G.A.; Serrão, E.A.; Zardi, G.I. Comparison of phototrophic shell-degrading endoliths in invasive and native populations of the intertidal mussel Mytilus galloprovincialis, Biological Invasions, 15, 6, 1253-12, 2013.