Invasive alien species and biodiversity: impacts and management

Abstract

As far back as the 18th century, many naturalists including Augustin Pyramus De Candolle and Charles Darwin, observed the phenomenon of non-native species. These were defined as ‘species outside of their bioregion which can possibly threaten native ones (De Candolle 1855; Darwin 1859; Pyšek et al. 2004). It was however only after the 1950s that scientists became aware that biological invasions can have a deleterious effect on habitats and ecosystems (Elton 1958; Macdonald and Jarman 1984; Davis 2009). The ‘father’ of invasion biology, Charles Elton, defined biological invasions as ‘ecological explosions’ meaning ‘the enormous increase in number of some organism’ in newly invaded ranges (Elton 1958). A combination of colonial rule, rapid economic development and increasing global trade exchanges across continents and borders have had a key role in human-mediated movement of propagules and species and have led to the subsequent establishment of non-native species in new regions outside their natural range (Turbelin et al. 2017). Indeed, the number of new recordings of invasive alien species (IAS) have incessantly increased worldwide during the last 200 years, but more than a third of all first introductions were recorded between 1970 and 2014 (Seebens et al. 2017). Over the last 30 years, numerous studies have demonstrated the negative effect of IAS on native biodiversity from the genetic (e.g. interspecific hybridization) to the ecosystem and landscape level (Largiadèr 2008; Kumschick et al. 2015; Lazzaro et al. 2020; Viciani et al. 2020). Today, biological invasions are considered among the main drivers causing biodiversity loss and species extinctions in the major plant and animal taxa across the world (IUCN 2017; Dueñas et al. 2021). Particularly, according to Bellard et al. (2016), IAS are the second most frequent threat connected with species’ extinction events since 1500. Besides biodiversity loss, the most recent literature on IAS has pointed out that these species have negative impacts on agriculture, ecosystem services and human well-being (including human health), ultimately causing serious economic problems (Pejchar and Mooney 2009; McGeoch et al. 2010; Paini et al. 2016). Economic damages due to IAS should include costs related to the direct damage caused by the species as well as those to be ascribed to their prevention, control and management (Marbuah et al. 2014). Even though environmental issues caused by IAS are recognized worldwide, knowledge on their current and future impacts on native biodiversity is still largely unknown (Downey and Richardson 2016; Essl et al. 2020). Numerous IAS can colonize, with different strengths, ecosystems in different bioregions of the world; whilst on the other hand, biological invasions are a continuous phenomenon and so far only observed for too short a period (i.e. mainly over the last century) to really understand the response of the native species assemblages and ecosystems. Yet, the management of the most invasive alien species is still challenging or an unsolved problem all over the world. For precisely these reasons, at Biodiversity journal, we felt it was high time we curated a themed issue, sharing examples from around the globe, on Invasive Alien Species and Biodiversity: Impacts and Management. Throughout, we have tried to provide new insights into such an important, and yet still under-studied area of research and scientific practice. In The spread of exotic fishes in the Italian rivers and their effect on native fish fauna during the last three decades the authors analysed 30-years of data recording (1985–2014) of fishes in Italy (BioFresh Project) with the aim to investigate the effects of introduced alien fish species on native species. The results showed that the richness of alien species is still increasing in Italy, while native species are decreasing. In addition, the invasion of the rivers in the Continental and Mediterranean biogeographic regions of Italy has induced more changes at the community level than the invasion of rivers in the Alpine region. Knowledge around IAS in the marine environment is still scarce. The synthesis Marine alien species: a challenge to biodiversity conservation in Marine Protected Areas. The case study of the Egadi Islands MPA (Tyrrhenian Sea, Italy) provides an insight into the management of IAS across Marine Protected Areas of the Mediterranean region describing the spread dynamics and future trends of nonindigenous organisms. Potential risks of invasive alien plant species on native plant biodiversity in Sri Lanka under climate change, Champika investigates the implications of the potential distribution of plant invasions on native biodiversity under climate change using a species’ modelling approach. Biodiversity-rich zones are at potentially BIODIVERSITY 2021, VOL. 22, NOS. 1–2, 1–3 https://doi.org/10.1080/14888386.2021.1929484