Prioritising surveillance for alien organisms transported as stowaways on ships travelling to South Africa
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Date
Authors
Faulkner, Katelyn T.
Robertson, Mark P.
Rouget, Mathieu
Wilson, John R.U.
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
The global shipping network facilitates the transportation and introduction of marine and terrestrial
organisms to regions where they are not native, and some of these organisms
become invasive. South Africa was used as a case study to evaluate the potential for shipping
to contribute to the introduction and establishment of marine and terrestrial alien species
(i.e. establishment debt) and to assess how this varies across shipping routes and
seasons. As a proxy for the number of species introduced (i.e. `colonisation pressure') shipping
movement data were used to determine, for each season, the number of ships that visited
South African ports from foreign ports and the number of days travelled between ports.
Seasonal marine and terrestrial environmental similarity between South African and foreign
ports was then used to estimate the likelihood that introduced species would establish.
These data were used to determine the seasonal relative contribution of shipping routes to
South Africa's marine and terrestrial establishment debt. Additionally, distribution data were
used to identify marine and terrestrial species that are known to be invasive elsewhere and
which might be introduced to each South African port through shipping routes that have a
high relative contribution to establishment debt. Shipping routes from Asian ports, especially
Singapore, have a particularly high relative contribution to South Africa's establishment
debt, while among South African ports, Durban has the highest risk of being invaded. There
was seasonal variation in the shipping routes that have a high relative contribution to the
establishment debt of the South African ports. The presented method provides a simple way to prioritise surveillance effort and our results indicate that, for South Africa, port-specific
prevention strategies should be developed, a large portion of the available resources should
be allocated to Durban, and seasonal variations and their consequences for prevention
strategies should be explored further.
Description
S1 Fig. The location of the five selected South African ports, and the benthic bioregions as
per Sink et al. [70].
S2 Fig. The number of ocean going vessels arriving at South African ports each year.
S3 Fig. Examples of pairwise-comparisons of the climatic conditions of ports.
S4 Fig. Examples of pairwise-comparisons of the marine environmental conditions of ports.
S5 Fig. The biogeographical regions as classified by Mead et al. [69] and the position of the five selected South African ports.
S6 Fig. The number of ship visits, number of days travelled, marine environmental distance and terrestrial environmental distance for the South African ports.
S7 Fig. The seasonal, relative contribution of shipping routes from foreign ports to the marine and terrestrial establishment debt of South African ports.
S8 Fig. Seasonal variation in the number of ship visits, number of days travelled, marine environmental distance and terrestrial environmental distance of the South African ports.
S9 Fig. The number of marine and terrestrial watch list species that might be transported along the twenty shipping routes to each South African port with the highest relative contribution to marine and terrestrial establishment debt.
S10 Fig. Temporal trends in the contribution of different regions to South African merchandise imports.
S1 Table. Details of the foreign ports included in the analysis.
S2 Table. Species on the watch list developed for South Africa by Faulkner et al. [71], the environment in which they occur (marine or terrestrial), whether they are found in climate zones or marine ecoregions that are associated with the source ports of high risk shipping routes, and if so whether they have a history of shipping-facilitated introduction.
S3 Table. Marine and terrestrial watch list species that might be transported along the twenty shipping routes to each South African port with the highest relative contribution to marine and terrestrial establishment debt.
S4 Table. The relative contribution of shipping routes from foreign ports to marine and terrestrial establishment debt.
S5 Table. The seasonal, relative contribution of shipping routes from foreign ports to the marine and terrestrial establishment debt of South African ports.
S2 Fig. The number of ocean going vessels arriving at South African ports each year.
S3 Fig. Examples of pairwise-comparisons of the climatic conditions of ports.
S4 Fig. Examples of pairwise-comparisons of the marine environmental conditions of ports.
S5 Fig. The biogeographical regions as classified by Mead et al. [69] and the position of the five selected South African ports.
S6 Fig. The number of ship visits, number of days travelled, marine environmental distance and terrestrial environmental distance for the South African ports.
S7 Fig. The seasonal, relative contribution of shipping routes from foreign ports to the marine and terrestrial establishment debt of South African ports.
S8 Fig. Seasonal variation in the number of ship visits, number of days travelled, marine environmental distance and terrestrial environmental distance of the South African ports.
S9 Fig. The number of marine and terrestrial watch list species that might be transported along the twenty shipping routes to each South African port with the highest relative contribution to marine and terrestrial establishment debt.
S10 Fig. Temporal trends in the contribution of different regions to South African merchandise imports.
S1 Table. Details of the foreign ports included in the analysis.
S2 Table. Species on the watch list developed for South Africa by Faulkner et al. [71], the environment in which they occur (marine or terrestrial), whether they are found in climate zones or marine ecoregions that are associated with the source ports of high risk shipping routes, and if so whether they have a history of shipping-facilitated introduction.
S3 Table. Marine and terrestrial watch list species that might be transported along the twenty shipping routes to each South African port with the highest relative contribution to marine and terrestrial establishment debt.
S4 Table. The relative contribution of shipping routes from foreign ports to marine and terrestrial establishment debt.
S5 Table. The seasonal, relative contribution of shipping routes from foreign ports to the marine and terrestrial establishment debt of South African ports.
Keywords
Shipping routes, Asian ports, Durban, South Africa, Marine, Pathways, Marine
Sustainable Development Goals
Citation
Faulkner KT, Robertson MP, Rouget M,
Wilson JRU (2017) Prioritising surveillance for
alien organisms transported as stowaways on
ships travelling to South Africa. PLoS ONE 12(4):
e0173340. https://DOI.org/ 10.1371/journal.pone.0173340.