Prioritising potential incursions for contingency planning: pathways, species, and sites in Durban (eThekwini), South Africa as an example

Abstract

Increased trade and travel have resulted in an increasing rate of introduction of biological organisms to new regions. Urban environments, such as cities, are hubs for human activities facilitating the introduction of alien species. Additionally, cities are susceptible to invading organisms as a result of the highly altered and transformed nature of these environments. Despite best efforts at prevention, new incursions of alien species will occur; therefore, prioritising incursion response efforts is essential. This study explores these ideas to identify priorities for strategic prevention planning in a South African city, Durban (eThekwini), by combining data from alien species watch lists, environmental criteria, and the pathways which facilitate the introduction of alien species in the city. Three species (with known adverse impacts elsewhere in the world) were identified as highly likely to be introduced and established in Durban (Alternantheraphiloxeroides,LithobatescatesbeianusandSolenopsisinvicta). These species are most likely to enter at either the Durban Harbour; pet and aquarium stores; or plant nurseries and garden centres – therefore active surveillance should target these sites as well as adjacent major river systems and infrastructure. We suggest that the integrated approach (species, pathways, and sites) demonstrated in this study will help prioritise resources to detect the most likely and damaging future incursions of alien species.

Climate and socio‐economic factors explain differences between observed and expected naturalization patterns of European plants around the world

“…SDMs are increasingly used as a basis to implement biosecurity policies, for example, by drawing up watch lists or lists of undesirable species (e.g. Padayachee et al., 2019). As biosecurity measures are usually taken at a regional scale while SDMs predict expected distributions at smaller scales, it is critical to determine which portion of a region should be suitable for an alien species to become naturalized, and hence, of concern.…”

The application of selected invasion frameworks to urban ecosystems

“…as a contaminant (stowaway) of a commodity) (Blackburn et al 2011). Owing to an increased number and variety of entry methods, urban areas experience multiple accidental introductions (Padayachee et al 2019).…”

The legacy of over a century of introductions: Spread debt of rainbow trout (Oncorhynchus mykiss) in Mpumalanga Province, South Africa

“…For example, establishment debt can be used to identify new invasions that have implications for the development of post‐border biosecurity and implementation measures to prevent the spread of potential invasive species (see Seebens et al, 2018). Spread debt can be used to identify additional areas that are likely to be invaded, and management implications include the identification of priority areas for control, the identification of areas where spread reduction methods are required, and spatial planning of the management of biological invasions (e.g., Khosa, Marr, Wasserman, Zengeya, & Weyl, 2019; Padayachee, Procheş, & Wilson, 2019). There are few studies that have investigated some aspects of invasion debt in South Africa, such as establishment debt (e.g., Faulkner, Robertson, Rouget, & Wilson, 2016; Novoa, Kaplan, Kumschick, Wilson, & Richardson, 2015; Walker, Gaertner, Robertson, & Richardson, 2017), spread of single species (e.g., Moore, Runge, Webber, & Wilson, 2011), and only one study has investigated all four components of invasion debt (Rouget et al, 2016).…”