status of the pathways of introduction

In document The sTaTus of biological invasions and Their managemenT in souTh africa 2017 (Page 54-58)

3. PathWaYS of iNtroduCtioN

3.3. status of the pathways

3.3.1. status of the pathways of introduction

based on socio-economic data, many of the pathways of introduction appear to be playing an important role in south africa and in many cases the prominence of these pathways has increased over time (see figure 3.1 and Table a2.1). There are 72 official ports of entry through which people, goods and transport vessels can enter the republic. eight of these are maritime ports, ten are airports and 54 are land border posts (figure 3.2). The number of people entering south africa through these ports of entry has increased over time, and in 2016 over 21 million people entered the country (figure 3.3). according to the World Tourism and Travel council (2017), over 10 million of these were tourists. Tourism and travel is an important industry in south africa and the contribution this sector has made to gross domestic Product (gdP) has increased over time (figure 3.4). The quantity of food imported into south africa through the ports of entry has also increased over time, and in 2013 over 7 million tonnes of food was imported (figure 3.5). These pathways are examples of many that are playing a major and increasing role in south africa, and as alien taxa could be transported into the country within the luggage of tourists, or as contaminants of imported food, these pathways, along with a number of others, might be playing an important and increasing role in the introduction of alien organisms.

Figure 3.2 South African ports of entry. Any person, who wishes to enter into or depart from South Africa, can only legally do so through these ports. Information was obtained from the South African Department of Home Affairs (2017).

ChaPter 3IPaThWaYs of inTroduc

Figure 3.3 The number people arriving in South Africa by air, road and sea transport in 2006 and 2016. Data were obtained from Statistics South Africa (2017).

2009 2011 2013 2015 2017 2019 2021 2023 2025 2027

2007

Year

45

Contribution to GDP (billions of US dollars at real prices)

40

1995 1997 1999 2001 2003 2005

Figure 3.4 The contribution of travel and tourism to South Africa’s gross Domestic Product has increased over time and is expected to continue to increase in the future. Data were obtained from the World Tourism and Travel council (2017).

Year

1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2011 20132005 2007 2009

Quantity of imported food (million tonnes)

7

Figure 3.5 The quantity of food imported into South Africa has increased, particularly since 2000. Data were obtained from the food and Agricultural organisation of the United Nations (fAo, 2017).

Tus of biological invasions and Their managemenT in souTh africa2017

as many introduction pathways are prominent in south africa, it is not surprising that alien taxa have been intentionally and accidentally introduced to the country through a wide variety of introduction pathways. although most alien taxa have been intentionally imported for the ornamental plant trade and then have escaped from gardens (figure 3.1, figure 3.6 and figure 3.7), many have also been released for biological control or have been introduced for agriculture (figure 3.1 and figure 3.7).

although most alien taxa have been intentionally imported into the country, a large number have also entered the country accidentally (figure 3.6). for example, many alien taxa have been introduced as contaminants on imported plants, or as stowaways on visiting ships (figure 3.1 and figure 3.7). organisms that have been introduced to south africa’s neighbouring countries have also spread into the country; however, no alien taxa are known to have spread into south africa through human-built transport infrastructure that connects previously unconnected regions (figure 3.1 and figure 3.6).

Pathway of introduction

Release in nature escape from confinement Transport – contaminant Transport – Stowaway corridor Unaided Unknown 0

500 1000 1500

Number of introduced taxa

Figure 3.6 Number of alien taxa introduced to South Africa through the pathways of introduction (following the categorisation scheme adopted by the convention on Biological Diversity), and the number of taxa for which pathway of introduction was unknown.

ReleASe IN NATURe

Number of introduced taxa

Biological control erosion control/

dune stabilisation fishery in the wild Hunting landscape/flora/

fauna improvement conservation purposes or wildlife

management

Release in

nature for use other intentional

release Not enough detail

animals forestry fur farms Horticulture ornamental purpose other than horticulture

Research

(in facilities) live food and live baits other

contaminant Timber trade Transportation

of habitat Not enough detail

equipment container/bulk Hitchhikers in

or on airplane Hitchhikers on ship/boat Machinery/

equipment People and

their luggage organic packing material Ship/boat

ballast water Ship/boat hull

fouling vehicles other means

of transport Not enough detail 0

100 200

Pathway of introduction

Figure 3.7 Number of alien taxa introduced to South Africa through the pathways of introduction, and the number for which designation at the pathway subcategory level was not possible due to insufficient information. The graphs show the results for the pathway subcategories of the (from top to bottom) ‘Release in nature’, ‘escape from confinement’, ‘Transport – contaminant’ and ‘Transport – Stowaway’ pathway categories. Results for the unaided pathway are not shown (see figure 3.6 for the results of this pathway).

ChaPter 3IPaThWaYs of inTroduc

although data were insufficient for many of the pathways of introduction, for some pathways data were sufficient to evaluate recent changes to the rate of introduction, and to assess the effectiveness of control measures. for eleven pathways, between 2000 and 2009 there was either a minimal change or an increase to the rate of introduction in comparison to that of the previous decade (figure 3.1). Therefore, although control measures were enacted for some pathways in the 1980s, for many pathways the rate of introduction has not declined (figure 3.1, also see box 3.1 for an example). The rate at which alien taxa have been introduced to south africa has declined for only one pathway: biological control (figure 3.1). regulatory process complications caused a decline in the number of taxa introduced for the biological control of invasive plants (Klein, 2011; Klein et al., 2011), while the number of insects released to control insect pests has also declined since the 1980s (cock et al., 2016). overall the introduction of biological control agents was, therefore, lower in the 1990s and 2000s than in the 1980s (see figure a2.4). as the complications in these regulatory processes have since been resolved, and as biological control research and implementation for alien plants has recently increased (Zachariades et al., 2017), it is likely there will be an increase in the release of biological control agents in the future (figure 3.1). There have been no new alien taxa introduced for fishing or aquaculture since the 1980s (figure 3.1; also see figure a2.4 and figure a2.5). While this decline might be due to the control measures that were implemented during this period [i.e. animal diseases act (act no. 35 of 1984)], changing fashions or other socio-economic factors could also have played a role. during the last full decade (2000–2009), the annual rate of introduction has fluctuated, with an average of 7 taxa introduced per year (figure 3.8). overall, and despite the control measures that are in place, the rate of introduction appears to be increasing (figure 3.9).

Year Number of taxa introduced per year

2005 2006 2007 2008 2009

2004 2001

0 2000 5 10 15

2002 2003

Figure 3.8 The number of taxa introduced to South Africa during each year in the last full decade.

Tus of biological invasions and Their managemenT in souTh africa2017 Number of introduced taxa

Time period

0 20 40 60 80 100

1950-1959 1960-1969 1970-1979 1980-1989 1990-1999 2000-2009 2010-2019

Figure 3.9 The number of taxa introduced to South Africa during each decade since the 1950s. Data for 2010 to 2019 were incomplete and are shaded in grey.

In document The sTaTus of biological invasions and Their managemenT in souTh africa 2017 (Page 54-58)