Invasive species trait-based risk assessment for non-native freshwater fishes in a tropical city basin in Southeast Asia

Abstract

Biological invasions have created detrimental impacts in freshwater ecosystems. As non-native freshwater species include economically beneficial, but also harmful, species, trait-based risk assessments can be used to identify and prevent the import of potentially invasive species. Freshwater fishes are one of the most evaluated freshwater taxa to date. However, such assessments have mostly been done in sub-temperate to temperate regions, with a general lack of such research in the tropics. In view of this knowledge gap, this study aims to determine if a different set of traits are associated with successful establishment of non-native fishes within the tropics. In tropical Southeast Asia, Singapore represents a suitable model site to perform an invasive species trait-based risk assessment for the tropical region given its susceptibility to the introduction and establishment of non-native freshwater fishes and lack of stringent fish import regulation. A quantitative trait-based risk assessment was performed using random forest to determine the relative importance of species attributes associated with the successful establishment of introduced freshwater fishes in Singapore. Species having a match in climate, prior invasion success, lower absolute fecundity, higher trophic level, and involvement in the aquarium trade were found to have higher establishment likelihood (as opposed to native distributional range and maximum size being among the commonly identified predictors in subtropical/temperate trait-based risk assessments). To minimize invasive risk, incoming freshwater fishes could be screened in future for such traits, allowing lists of prohibited or regulated species to be updated. The findings could also potentially benefit the development of invasive species action plans and inform management decisions in the Southeast Asian region. Considering a geographical bias in terms of having relatively less documentation of biological invasions in the tropics, particularly Asia, this study highlights the need to perform more of such risk assessments in other parts of the tropics.

Potential risky exotic fish species, their ecological impacts and potential reasons for invasion in Korean aquatic ecosystems

“…Among the multiple effects of a successful invasive species, it must have spread to the novel ranges, have massive environmental and economic consequences by threatening the human services rendered by the ecosystem (Emery-Butcher et al 2020). Some of the most crucial factors that help establish viable fish populations are the climate match with the native and novel area, prior success as invasive species, higher trophic plasticity, being attractive for multiple human uses (commercial fisheries, aquaculture, game fishing, ornamental trade), and have lower absolute fecundity rate (Cambray 2003;Chan et al 2021). Therefore, it can be summed up that if a species can harm the new ecosystem structure, quality, and physical habitat, it can pose a severe threat to human health and economy, can grow and reproduce rapidly, have the ability to establish viable populations, can spread even aggressively and cause a decline of native species are successful invaders.…”

The hidden risk of keystone invaders in Canada: a case study using nonindigenous crayfish

“…Managers are increasingly turning to tools like risk assessments to identify which species should be prioritized for limited resource allocations and to avoid lengthy and costly eradication efforts (Mandrak and Cudmore 2015;Marshall Meyers et al 2020). Trait-based assessments are one approach to identify higher-risk species (Chan et al 2021), including crayfish (Zeng et al 2015). Another complimentary approach follows the invasion cycle and several screening-level risk assessment tools have been developed (reviewed in Kumschick and Richardson 2013) with most being either decision trees (Reichard and Hamilton 1997;Kolar and Lodge 2002;Caley and Kuhnert 2006) or scoring systems (Pheloung et al 1999;Daehler et al 2004;Copp et al 2009;Drolet et al 2016).…”

Integrating invasive species risk assessment into environmental DNA metabarcoding reference libraries

“…For fish, perhaps the most widely used is the Fish Invasiveness Screening Kit (FISK; Copp, 2013 ), a question‐based spreadsheet tool adapted from the Australian Weed Risk Assessment that has been applied over 1900 times across 45 countries and six continents (Vilizzi et al, 2019 ). Other fish risk assessments tools have been developed to meet regulatory needs (e.g., the probabilistic US Fish and Wildlife's Freshwater Fish Injurious Species Risk Assessment model, Marcot et al, 2019 ), to provide more quantitative trait‐based predictions (Chan et al, 2021 ; Howeth et al, 2016 ), to consider vector‐specific factors (Chan et al, 2013 ), or to incorporate more detailed knowledge of species environmental tolerances (Gallardo et al, 2013 ) and habitat requirements (Poulos et al, 2012 ). Risk assessments can inform policy to reduce propagule pressure and the probability of accidental introduction and robust early detection surveillance programs that use either conventional direct capture methods or, as we show, passive surveillance or indirect detection methods such as eDNA metabarcoding (Simmons et al, 2016 ).…”