IAS_4.7.2_519

The impact database developed through this chapter highlights the incompleteness of information on impacts of
invasive alien species in Central Asia (mainly due to language barriers) and Africa. There are also discernible biases within regions. For example, in Africa, most impacts are documented from South Africa; eastern and northern Africa being much less covered.
These biases are observed across all realms, but especially in marine ecosystems, where the extent and timing of
research efforts lag behind terrestrial studies (Ojaveer et al., 2015). Quantitative data on ecological impacts are generally scarce, even in well-studied regions. Although research on marine invasive alien species is relatively recent (initiated in the 1960s and 1970s), there are already distinct geographic and taxonomic knowledge biases on impacts of marine invasive alien species. Impacts for the vast majority of marine alien species have not been quantitatively or experimentally studied over sufficiently long temporal and spatial scales,
and their cumulative and synergetic connections with other drivers of change affecting the marine environment are largely unknown. A literature survey on alien marine macroalgae revealed information on impacts for only 30 species globally (Davidson et al., 2015). Evidence for most of the documented ecosystem impacts in European seas is based on expert judgement or correlations, with only 13 per cent of the documented impacts inferred from manipulative or natural experiments. A similar paucity of impact data is apparent in North America. A recent synthesis of global ecological impacts21 comprises 76 species, about 4 per cent of documented marine alien species, and the ecological impacts of 49 of the species were quantified in only one study each.
This chapter also highlights biases in the study of impacts of invasive alien species across units of analysis: in the marine realm, most studies were confined to intertidal/shallow subtidal areas, and in the terrestrial realm few impacts have been documented in deserts, tundra and high elevation mountainous habitats.
The impact database developed through this chapter also reveals a lack of understanding and synthesis of impacts of invasive alien microbes across all regions of the world. Some microbes are pathogens of plants, animals or humans, and due to their small size and parasitic lifestyle, many microbes can frequently be transported, introduced and established.
While microbes can be considered as invasive alien organisms (Nuñez et al., 2020; H. E. Roy et al., 2017), they
have been long ignored in the field of ecology, and this could be a reason for their small representation.
Similar to trends in publications in other disciplines (Nuñez et al., 2021), many of the publications reviewed in this chapter focus on impacts occurring in a narrow set of wealthy countries. Although references in other languages could drastically improve the understanding of impacts of invasive alien species, about 95 per cent of the publications listed in the impact databased developed through this chapter are in English, severely underrepresenting studies in non-English scientific journals (Angulo, Diagne, et al., 2021; Nuñez &
Amano, 2021).