The invasion process of the non-indigenous mussel Xenostrobus securis (Lamarck, 1819)spread, impacts and the role of climate change

Zusammenfassung

In the inner part of the Ria de Vigo and Ria de Pontevedra, M. galloprovincialis used to be the only mussel species, but since the introduction of X. securis, the native species seems to have been displaced by the invasive species (Garci et al. 2007). This situation offers a good opportunity to understand the mechanisms of invasion and spread of the invader, and hopefully it will allow us to tackle the problem of new introductions in an early future. Thus, the aim of this thesis is to understand the distribution and mechanisms of invasion of the invasive mussel X. securis as well as its impact on associated fauna (Part 1). In addition, we want to explore how a future climate change scenario may affect to this species (Part 2). To fulfill all the proposed objectives, an experimental research program was carried out including monitoring studies and manipulative experiments in the field and in the laboratory. In the field, we carried out the observational studies of distribution and benthic assemblages (Chapter I and II) and the manipulative experiment of biotic interactions (Chapter III). In a mesocosm experiment at laboratory, we examined the responses of mussel assemblages of different composition to climate change by manipulating the temperature and pH of seawater (Chapter IV). Finally, we conducted a combined laboratory/field experiment to evaluate if past environmental stress (i.e. decreasing pH and increasing temperature) affected prey choices by the native dogwhelk Nucella lapillus (Linnaeus, 1758) and preys vulnerability (Chapter V).