Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Dynamics and processes influencing recruitment of the invasive mussel Xenostrobus securis and the coexisting indigenous Mytilus galloprovincialis in north-western Spain.

Abstract

The local extent of populations of invasive species is dependent on coupled dispersal- recruitment dynamics and subsequent interactions with the recipient community and the local environment. In this study several field experiments were conducted in order to investigate the main factors controlling larval supply (settlement and recruitment time-series), substrate selection (7 different treatments) and post-recruitment mortality (predation exclusion experiment) of the invasive mussel Xenostrobus securis and the coexisting, commercially important native mussel Mytilus galloprovincialis. The study aimed to evaluate differences between the two species in spatio-temporal patterns of recruitment along an estuarine gradient in the Ría de Vigo (NW Spain). Settlement and recruitment of X. securis were coupled to the distribution of the adult populations and were mainly restricted to the innermost part of the ria, in direct contrast to the patterns displayed by the native M. galloprovincialis. The recruitment period of the invader in the study area lasted 5 months, partly overlapping with that of M. galloprovincialis. Xenostrobus securis larvae did not display a substrate preference, whereas M. galloprovincialis larvae preferred substrates with the presence of conspecifics. Although predation pressure was greater on M. galloprovincialis than on the invader, size-dependent predation pressure was observed in both species, suggesting that smaller individuals are more vulnerable to predators. Density-dependent processes may also account for recruitment density, especially under low predatory pressure. Despite having life-history traits characteristic of a successful invader, X. securis populations have remained stable since 2012 and are mainly restricted to the inner part of the Ría de Vigo. This observation suggests that the species spread may be controlled by seasonal dispersal barriers associated with topographic features.