Pet stores, aquarists and the internet trade as modes of introduction and spread of invasive macrophytes in South Africa

Abstract

Submerged aquatic invasive plant species are increasingly being recognised as a major threat to South African water ways. Pet stores, aquarists and the internet-mediated trade were investigated as pathways for submerged invasive macrophyte introductions into South Africa. Online and manually distributed surveys were used to determine the extent of movement of invasive as well as indigenous submerged plant species in South Africa. Sixty-four stores and twenty-three aquarists were surveyed. Four areas of risk were identified in this study. Firstly, and most importantly, a variety of invasive and/or prohibited plants are sold by pet stores. Secondly, there is a lack of knowledge regarding identification as well as regulation of submerged species, which may then result in the unintentional trade of potentially invasive species. It seems that, in many cases, the pet stores are ignorant or misinformed of the potential dangers, rather than intentionally attempting to breach the legislation. Thirdly, aquarists own, trade and move plants in and around the country, which makes it very difficult to monitor which species are being moved around South Africa and to what extent. Finally, the internet is a pathway of potential concern, but it is difficult to quantify its contribution to the trade of invasive species in South Africa.

Insect herbivory on native and exotic aquatic plants: phosphorus and nitrogen drive insect growth and nutrient release

“…Exotic plants are introduced through aquaculture and global plant trade (Kay & Hoyle, 2001;Martin & Coetzee, 2011;Hussner, 2012) and they rank among the top four threats to freshwater biodiversity (Dudgeon et al, 2006) with more than 96 invasive exotic aquatic plants already established in Europe (Hussner, 2012). They grow fast, disperse quickly and easily establish in eutrophied ecosystems (Simberloff et al, 2011).…”

Understanding and managing the introduction pathways of alien taxa: South Africa as a case study

“…Since 1975 there has been a dramatic increase in the number of reptiles (individuals and species) imported into South Africa for the pet trade (van Wilgen et al 2010). Similarly, the increasing number of plant escapes likely reflects the prominent role of the ornamental plant trade (Foxcroft et al 2008;Martin and Coetzee 2011). These trends are not unique and globally there has been a decline in the release pathway for vertebrates (since ~1900; and an increase in the escape pathway for vertebrates (~1940s; Kraus 2007) and plants (from ~1780;Hulme et al 2008).…”

“…pet store or nursery owners) as well as the general public need to be educated on the risks posed, existing protocols and the identification of banned taxa (Reichard and White 2001;Martin and Coetzee 2011). To decrease propagule pressure (abundance in trade) and in turn the likelihood of escape, the sale price of high risk taxa could be increased (Dehnen-Schmutz et al 2007;van Wilgen et al 2010).…”

“…Finally, the attention of management and policy makers must be drawn to new, inconspicuous pathways that facilitate escapes, e.g. internet and traditional medicine trade (see Martin and Coetzee 2011;Wojtasik 2013 (Saccaggi and Pieterse 2013). Unfortunately the effectiveness of South Africa"s inspection protocols is unknown, and the increasing number of unintentional introductions indicates that quarantine services do not have the resources to properly police ports of entry (Giliomee 2011).…”

Invasive aquatic pets: failed policies increase risks of harmful invasions

“…The aquarium ambulia (Limnophila sessiliflora), hydrilla (Hydrilla verticillata), and the "killer algae" (Caulerpa taxifolia) were placed on the Act No. 36 of 1983 and the Federal Noxious Weed List of 1999 making it illegal to import these species into the U.S.A. and South Africa, respectively (Martin and Coetzee 2011;Díaz et al 2012).…”