Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade

Abstract

The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of freshwater molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded freshwater molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, molluscs sold as fish feed). We recorded an unexpectedly high diversity—59 species—of freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances. The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native freshwater molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient. Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring, and constitutes a step toward creating a more sustainable ornamental pet trade.

Self‐fertilization, long‐distance flash invasion and biogeography shape the population structure of Pseudosuccinea columella at the worldwide scale

“…A likely explanation is that it results from human activities occurring at global scale such as aquarium‐related plant trade (Duggan ; Ng et al . ) – P. columella is often found in artificial ponds and fish tanks; birds and flooding are other possible ways of dispersion but at shorter distances (Van Leeuwen et al . ; Simonová et al .…”

The ecophysiology of apple snails in rice: implications for crop management and policy

“…Species that appear innocuous in one region can cause problems when established in a new region, as has been the case with P. canaliculata and P. maculata . Despite these dangers, an international trade in apple snails for the pet and aquarium industry continues to be active (Ng et al ., ).…”

“…Apple snails (Ampullariidae) are freshwater snails that naturally occur throughout the humid tropics and subtropics. There are 10 genera and about 120 species (Hayes et al ., ); however, research attention has focused on a small group of snails (principally Pomacea spp., originally from the Americas) that since the 1960s have invaded new regions mainly through the pet and aquarium trade (Horgan et al ., ; Ng et al ., ) but also through deliberate introductions for food and cottage industries by both public and private institutions (Cowie, ; Hayes et al ., , ; Horgan et al ., ).…”

Next-Generation identification tools for Nee Soon freshwater swamp forest, Singapore

“…This is unfortunate because many environmental problems can be diagnosed using DNA barcodes, e.g. the presence of invasive species (Collins et al, 2012;Ng et al, 2016). As for plants, their genes evolve slower so that there is a larger proportion of closely-related species that are indistinguishable based on DNA barcodes (Hollingsworth, 2008;Hollingsworth et al, 2011).…”