Mechanisms of habitat segregation between an invasive ( Mytilus galloprovincialis ) and an indigenous ( Perna perna ) mussel: adult growth and mortality

摘要: The invasive mussel Mytilus galloprovincialis and the indigenous Perna perna coexist intertidally on south coast of South Africa through partial vertical habitat segregation: M. dominates upper shore P. lower shore. Recruitment patterns can explain zonation perna, but not species. We examined role post-recruitment interactions by measuring spatial temporal differences in adult growth mortality rates two Specifically, we tested hypothesis that interspecific reflect distribution patterns. study locations, Plettenberg Bay Tsitsikamma, are 70 km apart with sites (separated 300–400 m) per location, each divided into three zones. Growth was measured seasonally using different marking methods 2001 2003. Cumulative summer 2003/2004. Both species generally grew more slowly upshore, they showed effects season. For significantly reduced winter low zone, unaffected season high zone. galloprovincialis, either or increased winter, even Thus, under cool warm temperatures, respectively; while similar between summer, much faster than winter. Mortality upshore. zone-dependent greater for low-shore (generally) across Tsitsikamma. had higher seems able to maintain dominance at certain because galloprovincialis. conclude seasonality reflects their biogeographic affinities coexistence is possible pre-recruitment limit