Marine hitchhikers: a preliminary study on invertebrates unintentionally transported via the international pet trade

Abstract

The pet trade in aquatic organisms is a significant source of non-indigenous species introductions. In comparison with ornamental animals, unintentionally transported invertebrate assemblages are easily overlooked by traders and keepers. Moreover, hitchhiking species detection and identification is difficult even for experts. The densities of “hitchhikers” in aquaria may be relatively higher than those in the wild. These phenomena are known in freshwater aquaria but poorly studied in marine ones. We found 17 species of non-ornamental marine invertebrates in one of the leading importers of aquarium species in the Czech Republic in November 2017. The set comprised six gastropods, two bivalves, three cnidarians, two echinoderms, two crustaceans, and two polychaete worms. In one case, a symbiont was also detected, associated with the host “hitchhiker”. No “live rocks” are traded by the surveyed wholesaler. Thus, the found animals were not imported together with this item as larvae or eggs. Contrary to the transport of targeted ornamental species, it is clear that transport of “hitchhikers” is occurring despite standard legislative regulations and should be brought to the attention of conservationists, wildlife managers, policymakers and other stakeholders.

Survival, Growth, and Reproduction: Comparison of Marbled Crayfish with Four Prominent Crayfish Invaders

“…The accelerating rates of international trade, travel, and transport are leading to a mixing of biota across the world and the number of species introduced to new regions continues to increase worldwide [ 1 , 2 , 3 ]. This is true for many taxonomic groups [ 4 , 5 , 6 , 7 ]. Some of these introduced organisms become established and invasive in new environments, continuing to spread and negatively affecting their introduced environment [ 8 , 9 ].…”

Idea paper: Monitoring and databasing nonnative species to manage establishment debt in aquatic ecosystems

“…In particular, indoor bodies of water, such as aquariums, are a dominant medium of aquatic invasion (Cohen et al, 2007; Padilla & Williams, 2004; Strecker et al, 2011). Aquariums are often contaminated with unintentionally introduced nonnative species, referred to as “hitchhikers” (Duggan, 2010; Duggan et al, 2018; Ložek et al, 2021; Patoka, Bláha, Devetter, et al, 2016; Patoka, Bláha, Kalous, et al, 2016; Patoka et al, 2017, 2020). On the other hand, there are many indoor bodies of water and are usually under human control; accordingly, they are relatively easy to evaluate and manage.…”

Threats at home? Assessing the potential ecological impacts and risks of commonly traded pet fishes

“…While most species in the pet trade spend their entire lives in confinement, many are released or escape from producers, importers, retailers and owners, and can exert impacts on recipient ecosystems through predation, competition with natives, hybridisation, habitat degradation and the spread of disease and associated biota (Polo-Cavia et al 2010;Kraus 2015;Mrugała et al 2015;Emıroğlu et al 2016;Patoka et al 2016Patoka et al , 2020Lozek et al 2021). Reasons for release include displays of aggression, increasing size, and maintenance costs (Duggan et al 2006;Fujisaki et al 2010;García-Díaz et al 2015), or high reproductive output leading to overstocked tanks (e.g.…”