GREAT THREAT POSED BY EUROPEAN STARLING IN NATIVE SPECIES

European starling Sturnus vulgaris is a native species in Eurasia and North America. It has been introduced intentionally to countries like Australia, New Zealand and South Africa for aesthetic reasons and also for the control of insects, but it is now ironically considered as a pest itself. It has been recently introduced in South America where it is posing a serious threat to the continent because it is spreading very fast [1].

The descriptions of S. vulgaris include; medium sized, black songbird with short, triangular wings with spotted feathers and short tail. Breeding adults and no-breeding adults are differentiated by feathers. The feathers of a breeding adult are thin pointed with yellow bill and black in colour whereas the non-breeding has a black beak and light spots [1].

This alien species has the ability of growing very fast because it is a habitat generalist, it has the ability to utilize a wide variety of habitat types, nest sites and food sources. The fact that it co-exist with humans allows it to become established in agricultural fields, cities, sewage treatment and garbage dumps. [1]

They have a negative impact as they carry diseases like blastomycosis, beef measles and histoplasmosis which are of higher risk to human beings. [1].
Farmers are also experiencing huge problem caused by S. vulgaris as it damage crops, berries and grapes. They also transmit diseases to domestic animals by contaminating water and food sources through live storks.

The overabundance of starlings causes a lack of avian diversity, S. vulgaris drive-off native species like bluebirds (Siglia spp), Purple martin (Progne subis) and Tree swallows (Ridoprone bicolor). After a century of their introduction they contribute in the decline of the above listed species. They have observed taking over the nests of House Sparrows (Passer domesticus) [2].

They pose enough threat to songbird in a way that it is now allowed to kill starling in U.S and Canada and sometimes a bounty is given off to killers. They are not protected by American wild life Conservation laws which make the killing issue not surprising. In other cities their nests are destroyed by human intervention where they intentionally set up the nest boxes in backyards and wooded areas, some also allow Peragrine falcon to build up their nests so that they can help with the control of European starling, as Peragrine falcon are strong eaters of starlings [3].

Economic concern was found in airport at runaways as European starling causes aircraft disasters by clogging up engines causing a shut down of the plane.
One of the Economic benefits posed by European starling in agriculture is the regulation of the number of pests eating the crops. They also serve as food source for some cultures along the Mediterranean Sea [1].

The invasion of European starling is not environmental friendly, it is true that they do assist farmer by controlling pests but the problem still lies immediately as they finish the pests because they become pests themselves and start eating the crops. They also pose high health risk diseases to both humans and animals which concludes European starling as a higher risk invasive species that needs to be removed fast.

References

1. Matthews, S. and Brandt, K. 2006. South American Invaded: the growing danger of invasive alien species. [Internet]. 23 January 2007; 08:57 UTC [Cited 23 Jan 2007]. Available From:
http://www.gisp.org/casestudies/showcasestudy.asp?id=274&MyMenuItem=casestudies&worldmap=&country=
2. Peterson, R. T. 1947. A field guide to the birds. [Internet]. 23 January 2007; 10:17 UTC [Cited 23 Jan 2007]. Available From:
http://edis.ifas.ufl.edu/UW118
3. Wikipedia contributors. Peregrine Falcon [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 22, 07:02 UTC [cited 2007 Jan 24]. Available from: http://en.wikipedia.org/w/index.php?title=Peregrine_Falcon&oldid=102387030.


Dianah Nangammbi
Cilla CSIR
P.O Box 395
Pretoria
0001
Tel: +27 12 841 2133
Cell: +27 73 121 3589
Email: dnangammbi@csir.co.za
URL: http://wwwdianah.blogspot.com/

The Invasion of South Africa Biome by Feral Species (Opuntia Stricta - Prickle Pears)

The Opuntia Stricta has invaded South Africa biomes. It was regarded as the feral species, this because it invade the rocky slopes and river banks from domesticated environment. Opuntia Stricta is an indigenous species of North America1. It has been introduced in South Africa and other continent as ornamental plant, garden plant and it was used as a fence. The species grow as shrub.1

The Opuntia Stricta has a fleshy stem with no leaves 3.The fleshy stem grows like leaves and it has spines with hairy features. The spines make it unpalatable to other animal species. The Opuntia Stricta bears fruits that are palatable to humans. It was studied that it can cure sugar diabetes and stomach-ache. It also helps to reduce alcohol hangover. 3

Opuntia Stricta favourable habitant is in the rocky slopes and in river banks. However, it also invades disturbed area such as cultivated area and wetlands. The Opuntia Stricta has invaded the rocky slopes and riverbanks out compete the indigenous species.1

In south Africa Opuntia Stricta has been declared weeds this because when it invade the area it grows in dense that end up restricting the growth of other plant species. In Kruger National park (South Africa), the Opuntia Stricta has invaded large area. When opuntia stricta invade the area, it replaces other species.1

The opuntia stricta spread through garden wastes, some with water current.1 The Opuntia Stricta have the ability to grow from any parts of its fleshy stem. Birds and animal can spread other species of opuntia stricta like common pear 2. The management of this opuntia stricta considered difficulty when is done physically. This because it can grow again if it is not disposed well 2. Spraying with woody weeds and biological control are effective if they are applied well. This is because in warm climates it needs to be reapplied again in winter.2

In general, the feral species can have more impact in our ecosystem. This need to be addressed and managed before the species invades our biome from domesticated species.


Reference:
1. Global invasive species Database, 2006. [Internet] Cited 2006 Jan 24 Available from: http://www.issg.org/database/species/ecology.asp?si=104&fr=1&sts=

2. Opuntia stricta [Internet] Cited 2006 Jan 24 Available from: http://www.esc.nsw.gov.au/Weeds/Sheets/shrubs/S%20Prickly%20pear.htm

3. Wikipedia contributors. Opuntia [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 22, 19:39 UTC [cited 2007 Jan 24]. Available from: http://en.wikipedia.org/w/index.php?title=Opuntia&oldid=102492834.


Mr Elelwani Muanalo
CSIR Pretoria
NISL- Ecological Informatics
P.O. Box 395
Pretoria, 0001
Tel: +27 12 841 2133
email: emuanalo@csir.co.za
Blogger url:http://muanalo.blogspot.com/

"The best way to predict the future is to invent it" Alan

THE LEUCAENA LEUCOCEPHALA SPECIES AND ITS NEGATIVE IMPACT ON THE ENVIRONMENT

The Leucaena leucocephala is a scientific name. It has many different common names; wild tamarind, lead tree, jumby bean or lamtoro. This plants is belongs to the family of Fabaceae. It is also belongs to the order of fables and the class Magnoliopsida. Leucaena leucocephala is a native species of Central America and Mexico. The species is listed as widespread in South America.

The Leucaena leucocephala is listed as a weed in Brazil, Agentina and in Bolivia. In this place, the species is taken as serious invader in the Islands of Fernando de Noronha. The species spread all over the tropical and sub-tropical parts of the world. Leucaena leucocephala is one of the plants that are promoted by international agroforestry organisation. It was promoted for food purpose, because it produces nutritional food for livestock. The foliage and seeds of Leucaena leucocephala contains the amino acid called mimosine (Matthews and Brandt 2006). The mimosine acid is very poisons to other plants which lead to invade the riverbanks, roadsides, cultivated land, and forest margin and in waste land.

During 16 century Leucaena leucocephala again introduced into Philippines for the purpose of feeding the ruminant livestock. Now it is spread all over the pacific region of Asia where it is previously used as agroforestry. This plant is easily propagated from seeds but it may grow from cutting. Its seeds are dispersed by vertebrates’ animals such as birds and rodents. Now this species is not planted at all in Asia. Leucaena leucocephala is a slow growing tree especially when it grows in high altitude.

Leucaena leucocephala is a small thornless tree or shrub that can reach a height of 10m tall. In its home environment Leucaena leucocephala prefers to grow on coastal sands and on shallow limestone soils. This plant prefers many different types of soils because their roots systems allow it to tolerate many soils types. The Leucaena leucocephala can grow fast with a fertile clay soils (James A.D, 1983). It can grow in alkaline and saline soils and in area where there is low phosphorus and iron in soils. It can not grow in place where flood takes more than three weeks. Leucaena leucocephala prefers to grow with an optimal temperature of approximately 25 to 30 degrees Celsius.

The mature plants of Leucaena leucocephala are well adapted to fire and it can regrow from the burnt stumps. It is easily generate from basal shoots after fire (Lam, 2006). Leucaena leucocephala is a drought tolerant but it is poor adapted to infertile acidic soils. It also prefers to live in disturb areas like, along the road.

In its home environment the Leucaena leucocephala typically occurs as dense thicket forming. It is difficult to mitigate (eradicate) the L. leucocephala as it grow as a dense thicket forming. The glucoside mimosine produced by the seeds and leaves of L. leucocephala cause a problem with the hair of young cattle and horses in places where it introduced. Subspecies leucocephala is particularly precocious and free seeding.

It is concluded that L. leucocephala is accidentally introduced in South Africa by international agro forestry organisation. This organisation introduced this species because it produces the nutrition food for livestock. Unfortunately they are not aware that, this species produce mimosine acid which is very poisons to other species. The acid produced by the seeds and leaves of L. leucocephala destroy the forest margin and cultivated area in South Africa. This species threaten the biodiversity of South Africa because it has the possibility to spread over a long distance. The glucoside mimosine produced by the seeds and leaves of L. leucocephala destroy the hair of young cattle and horses.

The following methods can be used to eliminate the spreads of L. leucocephala species; Biological, Chemical and mechanical methods. A mechanical method involves the removal of invasive species using machines or hands. This method is most useful to eliminate the invasive species. Cutting or burning of L. leucocephala can be applied. This method is mostly useful at the beginning of the year.

Chemical method may also used. This method is used to prevent the spreading of L. leucocephala. This method involves the use of herbicides and pesticides. Herbicides can be used to destroy the L. leucocephala. It allows the person to cut down the stem of L. leucocephala and apply hebicides. Biological control method can be used. This methods is mostly useful to stop the spread of L. leucocephala by releasing new species. All this methods can be used to eliminate the spreads of L. leucocephala. Chemical and mechanical methods are the best methods to eliminate alien species as compared to biological methods.

References

James A.D.1983. Handbook of Energy Crops.[Online].[Cited, 23 January 2007].Available from:http://www.hort.purdue.edu/newcrop/duke_energy/Leucaena_leucocephala.html

Lam, D.W, 2006 Leucaena leucocephala [Online].[Cited, 23 january 2007].Available from: http://www.hear.org/pier/species/leucaena_leucocephala.htm

Linette Netshiheni
CSIR
Pretoria
0001
Cell: 0820446442
Tell: 012 841 2133
Fax: 012 842 3676
tnetshiheni@csir.co.za
Weblog: http://tnetshiheni-linette.blogspot.com/

FIRE ANTS GIVE A BURNING BITE

It was on the 4^th December 2006 when I read about the fire ants (Wasmannia auropunctata). I read the article from the "Daily Sun" newspaper and the article was talking about the dangerous of the fire ants. According to the daily sun, there are over 280 species of fire ants species on the world (1). The fire ants are reddish brown to black in colour. The length of fire ants ranges from 1millimetres and above. Fire ants are native at southern and central part of America and they are invaded in west of Africa (Gabon, Cameroon). According to the article, South African not yet invaded by Wasmannia auropunctata (2).

Fire ants prefer to dwell in disturbed areas (garden) and in riparian zones. They are also prefers to live in large colonies. Fire ants also produce mound in the open areas. Fire ants (Wasmannia auropunctata) are very dangerous insects for human and other species. Fire ants attack small animals and kill them by injecting venom (poison). Wasmannia auropunctata feeds on seeds, plants, and crickets.

Fire ants can bite and inject venomous sting into eyes of other species and it will cause blindness. The article also informs the people stay away from fire ants and not tough the nest of the ants because they can spray a powerful acid when it stings that will cause wound. Fire ants can cause declines in other organisms. They also compete with indigenous ants within the affected area.

References:

1. Sun Reporter. 2006 December 4. Daily sun. page 38 ( col 2)

2. Wetterer J. k. Wasmannia auropunctata. Global Invasive Species Database. [Online]. 2006 June 20.[Cited 2006 January 24]. Accessed on:http://www.issg.org/database/species/ecology.asp?si=58&fr=1&sts

Lizzy Maluleke

CSIR PTA

0001

Tell [012] 841 2133

Fax [012] 842 3676

E-mail mmaluleke@csir.co.za

Weblog: http://mmaluleke.blogspot.com

WATER HYACINTH AND ITS INVASIVENESS OUT OF THE CONTINENT OF THEIR ORIGIN

Water hyacinth is the plant which floats freely in the water. The plant is indigenous in
the continent of South America. Globalisation, International trade and transportation lead to the spread of water hyacinth in the continents of Africa, North America, Asia and Australia. In South Africa, Water hyacinth first came into existence in the province of KwaZulu-Natal in 1910 (Coetze, 2007) from South America. The species can rise to the height of approximately 1m in height above the water.

The species is now spreading in the Eastern part of South Africa. The plants serve as habitats for small invertebrates animals such as Fish and Frogs. The modes of dispersal include movement of People and Ships all across the boundaries. People move from one place to another either as part of tourism, trade, and other sport activities such as soccer, rugby and tennis. When People move from one place to another they use different types of transport such as trains, buses and planes. The types of the transport that they use carry the alien invasive species from one place to another. The species has been found to be a problem in Kenya where it suppresses other aquatic plants (Coetze, 2007). The plants float on the water and prevent sunlight from reaching other aquatic plants.

The prevention of the sunlight from reaching other aquatic organisms mean that other organisms will die because of the absence of the oxygen and the process of photosynthesis is reduced greatly. Lack of sunlight mean that the process of photosynthesis in water is no longer going to take place. If the process of photosynthesis is no longer going to take place, this means that plants which live in water such as algae (autotrophic) will no longer manufacture their own food. Small animals will die because there will be no longer food which is available for them. In countries such as Australia and Papua New Guinea, the plant destroys native plants. The killing of the native plants by water hyacinth is encouraged by the fact that, there are no preventive measures in place in the above mentioned two countries (Wikipedia contributors, 2007).

The dying of other aquatic organisms means that the aquatic ecosystem is disturbed because of the reduction in the quality of water. The reduction of the quality of water will also affect the livestock and People living around the affected areas. This is because in some parts of the globe, People are still dependent in water from the rivers. If the livestock are infected with diseases, this may also affect People feeding in the meat of those animals. The other problem in which water hyacinth possesses is that the species acts as a vector in which Mosquitoes build their nests. This means that Mosquitoes will be able to carry their diseases (Malaria) to the People who are living near to the area where the plants are available (Wikipedia contributors, 2007).

Water hyacinth forms fibrous roots which are thick, branched and dark in colour under the water. On top of the water, the species forms a thick mat which prevents many water activities such as swimming, fishing and canoeing. When the species dies, decomposers such as bacteria and fungi are responsible for the decaying of the dead organic matter. The dead organic matter provides other aquatic organisms in the water with food.


REFERENCES

Coetzee, J. 2000. Animals, Plants and the Environment [Online]. [cited 2007 January 18]. Available from: http://sunsite.wits.ac.za/ape/hyacinth.htm

Wikipedia contributors. Water hyacinth [Online]. Wikipedia, The Free Encyclopedia; 3 January 2007, 09:23 UTC (cited 2007 January 23]. Available from:
http://en.wikipedia.org/wiki/Water_hyacinth


Peter Muvhali
CSIR PTA
0001
Tell no: 012 8142133
Fax: 012 8423676
E-mail: smuvhali@csir.co.za
URL:http://blogsoccer-peter.blogspot.com

RED DEER AND ITS THREATS TO NATIVE SPECIES

Red Deer (Cervus elaphus) is indigenous in Britain but its ancestors are originally from Asia. Red Deer are found in the North West Africa, Asia, North West America, Western Europe and Western China (Wikipedia contributors, 2007). The lifespan of the Red Deer is approximately 25 years. The species is non-indigenous in Argentina and New Zealand. Red Deer is described as a large mammal which is dark red in colour which changes to brown in winter with even-ungulates because of the two toes (Clutton-Brock, Coulson and Milner, 2004). Red Deer are well adapted in New-Zealand while in Africa the population is faced with the extinction.

The species is regarded as one of the dangerous alien species in Argentina because of its negative impacts in the indigenous animals. The species out compete indigenous animals for food. In Scotland, Red deers are preventing the regeneration of the woodlands; this is because the number of Red Deers is in the rise and this can lead to the extinction of the woodlands. Red Deer live in woodlands and swamps of the coniferous forest. Red Deers are accused of spreading diseases to indigenous animals (Senseman, 2002). The diseases which the Red Deer spread include meningeal worms and bovine tuberculosis. The species are also accused of out-competing the native animals because of overbrowsing. Some of the farmers regard the Red Deer as pests because of overbrowsing of their cultivated plants which lead to the loss of production and cause soil erosion when there is precipitation. Red Deer provides people with teeth, food, fur and antlers (Senseman, 2002).

Red Deers feed on leaves, twigs and lichens during winter. The species is recognized by means of its stags. After two years, stags start to make branches that develop into antlers. The components of antlers include solid bones which become shed during April and March. The skin develops all around the solid bones with the blood vessels supplying the blood. The supply of the blood is ended after the antlers grow to its full size. Red Deers create important changes in the structural components of the indigenous ecosystem (Moore, 2005). The regeneration of the forest is also inhibited in the area of low density because of these giant animals.


REFERENCES

Coulson, T.; Clutton-Brock, T. H.; and Milner, J. M. (2004). Red deer stocks in
Highlands of Scotland [Online]. [cited January 23, 2007]
Available from: http://www.nature.com/nature/journal/v429/n6989/full/429261a.html

Moore, A. B. 2005. Alien invasive species: Impacts forests and forestry [Online]. [cited 19 January 2007]. Available from: http://www.fao.org/docrep/008/j6854e/J6854E00.HTM

Senseman, L. R. (2002). Cervus elaphus [Online]. [cited 18 January 2007]. Available from: http://animaldiversity.ummz.umich.edu/site/accounts/information/Cervus_elaphus.html

Wikipedia contributors. Red deer [Online]. Wikipedia, The Free Encyclopedia; 21 January 2007, 09:23 UTC (cited 2007 January 23]. Available from:
http://en.wikipedia.org/wiki/Red_Deer

Peter Muvhali
CSIR PTA
0001
Tell no: 012 8142133
Fax: 012 8423676
E-mail: smuvhali@csir.co.za
URL:http://blogsoccer-peter.blogspot.com

Salvinia molesta

Salvinia molesta is a scientific name for Kariba weed. Salvinia molesta was originally from Brazil and it is well known as a free-floating water fern. This species was found in the Zambezi River in Africa in about 59 years ago. Salvinia molesta has also invaded other countries around the world.

Department of the environment in Australia describes Salvinia molesta as a free-floating rapid-growing, mat-forming, annual fern; individual plants up to 30 cm long with numerous leaves. At the early stage the species leaves lie flat on the surface of the water and at the late stage the leaves bend at the edges, this features distinguishe S. molesta from S.minima. Salvinia molesta can grow rapidly (double within one week) to cover the entire water surface with a thick mat of vegetation. Salvinia molesta causes a great impact in aquatic environment and local economics. It affects the aquatic environment by preventing atmospheric oxygen from entering the water by doing this, it makes the water unfavourable for aquatic animals and it also reduces biodiversity of wetlands. It also dangerous to people since it “provide an ideal breeding environment for disease-carrying mosquitoes” [1]. In Senegal River, Salvinia molesta cause a threat to the biodervisity of the ecosystem conserved by Djoudj National Park.

Salvinia molesta spread quickly in a favourable condition and in size can double almost every two days. It spreads it selves during flooding and by human activities into new catchments. This species can leave under frozen temperature and on the water temperature up to 43°C. It can also survive under a dry condition.

The Australian Government, Department of the Environment and heritage suggested the better method for preventing the spread of Salvinia molesta since is a threat to the biodiversity, the public must be educated not to spread invasive species deliberately and “monitoring should be undertaken in catchments at risk from salvinia invasion” after floods [2].


References:

1.Unknown. Salvinia molesta, Weeds of National Significance: Weed management guide. Department of the Environment and Heritage and the CRC for Austrialian Weed Management, 2003. [Internet] Available from: http://www.deh.gov.au/biodiversity/invasive/publications/s-molesta.html
2. Cronk Q.C and Fuller J.L (1995). Plant invaders. Champman and Hall. [Internet]. Available from
http://www.hear.org/pier/species/salvinia_molesta.htm

Ramapulana Nkoana
CSIR Pretoria
0001
Cell:+27 73 347 6551
Tell:+27 12 841 2133
Fax:+27 12 841 4405

Email: pnkoana@csir.co.za
: puli.nkoana@gmail.com
My blogger URL: http://pnkoana.blogspot.com/

GLOBAL CHANGE AND BIOLOGICAL INVASION

The global change and biological invasion are currently the main topics in ecology around the world. Global change and biological invasion is a world wide problem. Both are said to have environmental and communal inference. Different studies suggest that Climate change which is caused mainly by human activities may directly or indirectly aid the success of the biological invaders. [1]

Global change includes numerous environmental and ecological alterations that occurs world wide. It includes change in ecology and environment as well as climatic composition of the atmosphere. Biological invaders are referred to plant and animal species not endemic to the particular country. [2 and 3]

Rising in the atmospheric Carbon Dioxide (CO2) plays a role in the success of many invaders. According to Dukes and Mooney 1999, there is a positive respond by invasive plants where CO2 is prominent. For example, the lantana camara which is an indigenous in the south and Central America is known to have tolerance in many environmental conditions even where CO2 is increased. The Bromus rubens grass is known to grow where there are warmer climates and they are favoured by increased CO2. They are well adapted to fire and they increase their dominance where fire occurred [1]. According to the GISP the effects of invasive alien species are worsened by global change and chemical and physical disturbance to species and ecosystems [4]

Land use change is also playing a role in the increase in success rate of the invasive species. In disturbed such as farming areas and disturbed areas for development is more prone to invasion. Most invasive species have competitive capabilities and they can grow and reproduce faster than the native species. The lantana camara are able to release chemicals that prevent other plant species from growing. This process is known as allelopathic mechanism. The lantanas are able grow forming a dense thickets which also prevent other from growing. [1 and 4]

Different studies show that there evidence that global change is playing a role in biological invasion and global change. It is how ever recommended for more studies to be done on global change and biological invasion. More observational and experimental studies must be undertaken to deal with this problem.

Reference:

1. Dukes JS and Mooney HA. 1999. Does global change increase the success of invaders? Trends Ecol Evol 14: 135-39.
2. Wikipedia contributors. Global change [Internet]. Wikipedia, The Free Encyclopedia; 2006 Jun 11, 19:53 UTC [cited 2006 Jul 11]. Available from: http://en.wikipedia.org/w/index.php?title=Global_change&oldid=58080847.
3. Wikipedia contributors. Invasive species [Internet]. Wikipedia, The Free Encyclopedia; 2006 Jul 9, 04:21 UTC [cited 2006 Jul 10]. Available from: http://en.wikipedia.org/w/index.php?title=Invasive_species&oldid=62830037
4. GSIP. Africa invaded: Lantana [Internet]. [Cited 2007 Jan 24]. Available from
http://www.gisp.org/casestudies/showcasestudy.asp?id=57&MyMenuItem=casestudies&worldmap=&country=

Mr Lufuno Mukwevho
CSIR Pretoria
P.O. Box 395
Pretoria, 0001
Tel: (012) 841 2133
Fax: 012 842 7024.
Cell: 0723175626
E-mail: lmukwevho@csir.co.za

ACACIA MEARNSII IS A THREAT TO SOUTH AFRICA

South Africa is facing a loss of biodiversity caused by the Invasive alien species. Invasive alien species is species introduced to a certain area where they never occurred before and have negative impacts to that area. Invasive alien species has the ability of harming the environment or human health. These species includes plants, animals, microbial and microscopic species [ISAC 2006].

Acacia mearnsii is a threat to South Africa. This alien invasive species is native in Australia and were introduced in South Africa 154 year ago [De Bakker 2003]. Acacia mearnsii is known as the Black Wattle Tree. This species can grow between five to ten meters in height [Anon 1999].The seeds of Acacia mearnsii are dispersed by cattle, birds and water. Birds and water can disperse seeds faster for long distance compared to the cows. This species reproduce through coppice of the seeds because they are small enough to be dispersed.

Acacia mearnsii outcompete native plants for water, nitrogen and organic materials. Acacia mearnsii has a potential of reducing the catchment water yields. Dye and Jarmain (2004) conducted a study in 2004 at Western Cape (Wellington and Groot Drankennstein) and KwaZulu- Natal (Seven Oaks) about water use by Acacia mearnsii. They discovered that Acacia mearnsii use 7mm of rainfall per day and they estimated additional loss of 185 mm of rainfall used annually by Acacia mearnsii. Therefore, each species use the total amount 2740 mm of rainfall annually. I can imagine if ten species are found in one area. South Africa as a water scarce country is faced with the challenge of the spread of Acacia mearnsii, especially the planners, manager and the policy makers that have to come up with the strategies of how to control the Acacia mearnsii species [Dye and Jarmain 2004].

This species provides wood for fuel especially, in the rural areas. Acacia mearnsii prevent erosion because it consists of the long roots that hold the soil particles together. Rouget et al (2002) indicated that Acacia mearnsii and Pinus species “occupy 60% area under commercial plantation and 54% of the area invaded by the alien trees and shrubs”.

However, Acacia mearnsii is a threat; it also provides a good commercial product, Soft – leather, building houses, fencing, electric poles, as woods, etc. The cutting of this species is of importance for commercial use and to save the little water that we have in South Africa.


References:

Anonymous. 1999. Acacia Mearnsii. Available from: http://www.hear.org/Pier/species/acacia_mearnsii.htm.

De Bakker L. 2003. Combating the aliens. Radio Netherlands, Science Unit. Available from: http://www.radionetherlands.nl/features/science/030825alien.html

De Wit M.P, Crookes D.J and van Wilgen B.W. 2001. Conflicts of interest in the environmental management: estimating the costs and benefits of a tree invasion. CSIR Division of water, Environment and Forestry Technology. P167-169.

Dye P. and Jarmain C. 2004. Water use by black wattle (Acacia mearnsii): implications for the link between removal of invading trees and catchment streamflow response. CSIR Division of water, Environment and Forestry Technology. P 40-43.

ISAC (Invasive Species Advisory Committee). 2006. Invasive Species Definition Clarification and Guidance White Paper. Available from: http://www.invasivespeciesinfo.gov/docs/council/isacdef.pdf

Rouget M, Richardson D.M, Nel J.L and Van Wilgen B.W. 2002. Commercially important trees as invasive aliens – towards spatially explicit risk assessment at a national scale. Institute for Plant Conservation, Botany Department, University of Cape Town. P 397 – 398.

Image Credits

http://www.hear.org/starr/hiplants/images/thumbnails/html/acacia_mearnsii.htm

Ms Evelyn Maleka
CILLA CSIR
P.O. Box 395
Pretoria,
0001
Tel: (012) 841 2133
Fax: (012 )841 4405
Email: emaleka@csir.co.za
http://malekaevelyn.blogspot.com/

ECONOMIC EFFECTS OF INVASIVE ALIEN SPECIES

According to the report by global invasive species programme (GISP) 2003; invasive alien species are posing a serious threat to the world economy. From the ecological point of view, this problem is affecting the biological diversity resulting to its reduction. The most valuable agricultural systems which people depend on for food production are also affected. [1]

Invasive alien species are continuing to pose some negative impacts on the economy through-out the world. The invasive alien species is a problem threatening the value of biodiversity in South Africa. The proliferation of weeds has brought many problems in valuable farming lands. Weeds are opportunistic plants that take advantage of the manipulated agro ecosystem environment to grow and reproduce rapidly. While growing they exert competitive pressure on crop plant [2]. The quantity and quality of crop yields are reduced. Example the kariba weeds (Salvinia molesta). A Kariba weed is a water floating fern and it is native to Brazil. These directly affect the production of foods. [1]

The kariba weeds affect the agricultural sectors in many ways such as blocking the water pipelines, irrigation schemes and other water ways. Harmful aquatic organisms including bacteria and viruses [1] are discharged from the ballast water. Commercial fishing industries are affected hence result to decrease in the economy. [1]

In South African cape floral kingdom, the establishment of weeds decreases the supply of water to the surrounding communities and threatens the native biodiversity [1]. This resulted to the government spending millions of rands on manual and chemical control of the invaders [1]. The invasive are said to have the indirect consequences to the environment which increase the cost for management and prevention. Invasive may cause changes in nutrients cycling, hydrological cycle etc [1].

In many parts of Africa, food production is affected by invasive alien insect’s pests. The white cassava (manihot esculenta) meal bugs are serious threat to agricultural sectors. The invasive weeds make it difficult to restore land for future use because they are able to grow faster. Weeds increase the risk of fire because when they dry-up, the area become prone to fire. Increase in fire result to changes in soil chemistry where it becomes uninhabitable by other by other types of plants [1]. The water hyacinth ( Eichhornia crassipes)uses enough water resulting to competitions between the native plants and the invaders. The invasive are able to with stand and survive until they out compete the native species. [1]

In agricultural sectors, this is costing a lot of money for government around the continent. The current situations indicate that there is a serious threat by the alien invasive species. Much need to be done in order reduces this problem. More efforts on eradication and prevention need to be strengthened.




Reference:

1. GSIP. Africa invaded: Lantana [Internet]. [Cited 2007 Jan 24]. Available from
http://www.gisp.org/casestudies/showcasestudy.asp?id=57&MyMenuItem=casestudies&worldmap=&country=

2. Wikipedia contributors. Weed [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 21, 09:14 UTC [cited 2007 Jan 24]. Available from: http://en.wikipedia.org/w/index.php?title=Weed&oldid=102182870.


Mr Lufuno Mukwevho
CSIR Pretoria
P.O. Box 395
Pretoria, 0001
Tel: (012) 841 2133
Fax: 012 842 7024.
Cell: 0723175626
E-mail: lmukwevho@csir.co.za

THE NEGATIVE IMPACTS OF CHROMOLAENA ODORATA ON THE ENVIRONMENT

I would like to share with you the little information I gathered on C.odorata species. The C. odorata species originates from South and Central America has different common name; Siam weed, or Ortriffid. In its native environment it occurs as a dense “thicket forming” shrub which prevent the establishment of other species. C. odorata is a perennial shrub that can grow up to the height of 3m. However, if growing as climber, it can reach the height of 10 m owing to its fast growing behaviour of 20mm per day.

The C. odorata consist of a single stem with branches growing in pairs to form auxiliary buds. It produces white flowers that contain small seeds of about 3 to 5mm long every year. As it forms a dense thicket, it reduces the level of biodiversity thereby suppressing the growth of young trees. The seeds of C. odorata species can disperse for long distances with its transport media being wind, water, humans, machinery and vehicles. It has relatively large seeds bank longetivity.

The C. odorata is easily propagated from root fragment, stem and from seeds (King and Robinson, 2006) and it preferably grow in open freely-drained ground area with annual rainfall of more than 1200 mm (King and Robinson, 1997). C. odorata can grow in many different types of soils. It prefers to grow in well-drained soils and can not survive on moist and saline soils. The C. odorata has short juvenile period. The C. odorata may also occur in disturbed areas, agricultural areas, planted forest, and also in riparian zones but can not tolerate shade.

This species was introduced in Africa and in tropical regions of Asia where it became a problem, as it is considered a very invasive weed in subtropics and in humid tropics of the world. The species is non-indigenous in India, Africa, Indonesia, Sri Lanka, Malaysia and Indochina (Leslie, 2001).

In South Africa, this species was first observed in the province of Kwazulu Natal. The transport media of this plant is likely water and machinery as it resulted from the materials of packaging that were contaminated when offloaded from the ships at Durban harbour. The date in which the species was first introduced is still unknown. In 1986, C. odorata invaded other parts of provinces and countries such as Limpopo, Eastern Cape, Mpumalanga, Botswana, Mozambique, Zimbabwe and Swaziland (Leslie, 2001).

The C. odorata became a serious invader in South Africa. It possesses a major threat to agriculture, Conservation and forestry. C. odorata can easily invade the riverbanks, as a result destroying habitats of other species. For example, In South Africa, C. odorata destroyed the nests of crocodiles in St. Lucia Lake.

It is taken as a serious invader in South Africa as it is perennial and fast growing plants. The C. odorata is a major threat in South Africa because its seeds are spread rapidly over a long distance. The problem with this species is,it destroy South Africa vegetation.

The handpulling method can be used to mitigate the spread of this species, more especially in young plants. Herbicides can also be used in order to kill the mature C. odorata species. Annual burning regimes can effectively controls the invasion of C. odorata. This is because fire would kill the mature plants and prevent new seedling from establishing. Biological control may also be used.

References

King R.M and Robinson H. 1997. Chromolaena odorata [Online]. [Cited, 22 January 2007]. Available from: http://www.bangor.ac.uk/~afs101/iwpt/web-sp4.htm

King. R.M. and Robinson. H.2006. Chromolaena odorata [Online].[Cited, 23 January 2007]. Available from: http://www.hear.org/Pier/species/chromolaena_odorata.htm

Leslie, J.A. 2001. Chromolaena story, [Online]. University of Stellenbosch, South Africa. [Cited, 21 January 2007]. Available from:http://www.issg.org/database/species/ecology.asp?si=47&fr=1&sts

Linette Netshiheni
CSIR Pretoria
0001
Cell: 0820446442
Tell: 012 841 2133
Fax: 012 842 3676
tnetshiheni@csir.co.za
Weblog: http://tnetshiheni-linette.blogspot.com/

NEED OF CONTROLLING LANTANA CAMARA INVASION IN AFRICA.

Lantana camara is an indigenous plant of South America. [1] The species was introduced in most of the country as ornamental plant. It has been declared invasive in most part of the world. The invasiveness of lantana camara has also been recognized in African continent. The invasion of lantana camara in Africa need attention as it has economic and social impact, which is influencing poverty in the continent.

The Lantana camara grows as weed in a thicket forming shrub that can spread to various environment. The leaves of Lantana camara are rough and hairy with aromatic smell when grind. [4] It flower grows in on the axils near the stem. [4]The flowers have various colours, it starts to bear flower with pale colour and change to orange when they are old. The fruits of lantana camara look like berry, the fruit contain one seeds. [4] In some parts of the world, lantana camara fruits are eaten and it is palatable to some animal especial goat.

The Lantana camara grows in high rainfall areas, in areas with tropical temperature. The species grow in organic soil, this tend to make it easy to invade sub Sahara regions. The species invade disturbed area like cultivated area. Its habitant of lantana camara includes range land, waste place and near the fence. In most of the African continent, the species was introduced for ornamental purpose and it then spread. [4]

The lantana camara spread more easily, through vegetative reproduction. [4] Where stem sends shoots it o the soil, allowing it to form dense stand and spread. [4] It also spread through pollination where birds and other animals carry seeds for long distance. [4] The ability of lantana camara to colonise area easily is because it can release chemicals in it surrounding that can prevent germination and growth of other plant species around.[2]

In African continent, the management of lantana camara need to be taken into consideration. It brings confusion in the context of alien species, this because it cannot be considered invasion in the country side of Africa. Some animal and people ate its fruits and it cannot be seen as alien invasion in the country side of African continent. In India, it has been used as herbal medicine; it can also be used as fuel wood. [3]

The invasion of the lantana camara has social and economic impact, which needs to be controlled mostly in Africa. It invades cultivated land, in which it releases chemicals to make it difficult for the growth of other plant. [2] This tends to reduce the crop production in Africa. This is because the herbicide control is expensive, the disadvantage group cannot afford to use it to control the spread of lantana in their farms. [2]

The use of other alternative method to control lantana camara can also have impact on our biodiversity. [2] Methods such as fire and physical control can influence the introduction of other alien species. fire burn the species and allows regeneration, whichmake it easy of invasion of new species. [2] This method need to be used with more attention of its advantage of introducing new species.

In general, the invasion of lantana camara in Africa has influence on reducing crop production. It also affect the animals stock, this because lantana camara have toxic chemicals that can affect animals. [4]

Reference:
1. Global invasive species program, 2003. Africa Invaded: Lantana [Internet] Cited 2006 Jan 24 Available from:
http://www.gisp.org/casestudies/showcasestudy.asp?id=57&MyMenuItem=casestudies&worldmap=&country=

2. Verbenaceae L. 2007. Pacific Island Ecosystems at Risk (PIER): Lantana camara
[Internet] Cited 2006 Jan 24 Available from:
http://www.hear.org/Pier/species/lantana_camara.htm

3. Global invasive species Database, 2006. Lantana camara (shrub) [Internet] Cited 2006 Jan 24 Available from: http://www.issg.org/database/species/ecology.asp?si=56&fr=1&sts=

4. Weeds of National Significance: Weed Management GuideDepartment of the Environment and Heritage and the CRC for Australian Weed Management, 200. Lantana (Lantana camara) [Internet] Cited 2006 Jan 24 Available from:http://www.deh.gov.au/biodiversity/invasive/publications/l-camara.html


Mr Elelwani Muanalo
CSIR Pretoria
NISL- Ecological Informatics
Email: emuanalo@csir.co.za
Blogger url: http://muanalo.blogspot.com/

ALIEN PLANTS SPECIES THAT INVADED ABOUT 50 COUNTRIES IN THE WORLD.

There are many alien species in our county that and some people were not aware that they are planting invasive alien plants that can poison natural species. Lantana camara is a shrub found in the bush and is native at central and south part of America (1). Lantana camara preferred to grow in fertile soils, where there is enough water and it can survive drought season. The height of Lantana camara is 1.8 metres tall. Lantana camara has opposite leaves that are 5 to 12 centimetres long and the wide ranges from 3 to 5 centimetres. The leaves of Lantana camara also have rounded teeth. The leaves of Lantana camara have sweet smelling and hairs. The stem and leaves of Lantana camara are covered by hairs (2).

The fruits of Lantana camara are greenish-blue to black in colour and they are fresh. Lantana camara has vigour (poison) that kills Herbivores animals (rabbits, cattle, and sheep) feed on its leaves. The vigour can also cause sores at the eyes, mouth, and noise of herbivores animals that feed on its leaves (3).

The research about the invasive alien species is done and the result indicated that South Africa is evaded by over 9000 species (4). The researchers also found the 198 of alien species are invaders species and they caused an ecological threat to native species (1). According to the Eden wildy, about 576 million meters square (m²) alien species invade and replace the native plants in KwaZulu-Natal per year (4). This is too bad because the area will end up dominated by alien species.

Lantana camara is regarded as a major problem and it is not easy to be controlled. Agricultural and natural lands are the most areas that are invaded by Lantana camara. Lantana camara is also a poison to the crops (coffee and bananas). Human, birds and animals have been contributed on speding the weeds accidentaly in KwaZulu Natal. Some people planted Lantana camara at their fence rows not knowing that they are planting a invasive plants. Lantana can cause the death to the native species and people must stay away from them.

Many solutions can be done to control or reduce spreading of alien invasive species in our home and county as a whole. The programme of working for water must organise an environmental awareness campaign to communities. It will help the people who do not know about alien invasive species. Let the community know the danger of the alien invasive species. Landowners must check their land every time. People must carefully clean their cloths after visiting the bush. Medias ( radios, television, and newspapers) can be used to teach people about alien invader plants. Hands can be use to pull the invasive alien species. One can cut down the stem of alien species and apply or spray herbicides on the stem to kill invasive alien species.

References:

1. Eden Wildy. Lantana camara. Alien Invaded Plants.[ Online]. 2006 April 23. [Cited 2007 January 22]. Accessed on: http://www.geocities.com/wessaaliens/species/lantana.htm

2. Anonymous. Lantana camara. Floridata. [ Online]. 2006. [cited 2006 January 23]. Accessed on:
http://www.floridata.com/ref/l/lant_c.cfm

3. Anonymous. African Invaded:Lantana camara. The Global Invasive Species Progamme. [ Online]. 2003. [ Cited 2007 January 22]. Accessed on:
http://www.gisp.org/casestudies/showcasestudy.asp?id=57&MyMenuItem=casestudies&worldmap=&country=

4. Eden Wildy. Lantana camara. Alien Invaded Plants.[ Online]. 2006 April 23. [Cited 2007 January 22]. Accessed on: http://www.geocities.com/wessaaliens/index.htm

Lizzy Maluleke
CSIR PTA
0001
Tell [012] 841 2133

Fax [012] 842 3676

E-mail :mmaluleke@csir.co.za

Weblog: http://mmaluleke.blogspot.com

THE INVASION OF MEDITERRANEAN MUSSEL (Mytilus galloprovincialis) IN THE WEST COASTAL PARK OF SOUTH AFRICA

The Mediterranean mussel (Mytilus galloprovincialis) is a native species in the Mediterranean Sea, Black Sea and Adriatic Sea. It dominates the out coast of France, Britain and Ireland but still unclear whether it is native to these countries. Mytilus galloprovincialis is dark blue or brown to almost black in colour. It possesses two shells which are equal and quadrangular in shape. (Branch and Stephanie 2004).


In the late 1970s the Mytilus galloprovincialis invaded South African coast. It was intentionally introduced for the purpose of aquaculture. It arrived in South Africa and occupies the Langebaan Lagoon. A Lagoon is a body of water cut off from a large body by a reef, sand or coral. The West Coast national park is a home to the Langebaan Lagoon which is recognised as a RAMSAR wetland site of international importance, and these wetlands are designed like sand beds. As a marine global invader Mytilus galloprovincialis was introduced via marine transport, it has been transported by ship ballast water to South Africa.

The introduced species started to out-compete the indigenous black mussel (choromytilus meridionalis) and also threatens the indigenous Perna perna. Its rapid spread has resulted in a decline of this endemic species. Ironically the Mediterranean mussel has become the stronghold of the mussel mariculture industry in Saldahna Bay.

Mytilus galloprovincialis grow so faster in the Lagoon than native mussels because the Lagoon provides more food which enables it to produce more offspring. The species is more air tolerant and have a reproductive output of between 20% and 200% greater than that of indigenous species. (Branch and Stephanie 2004). The problem with its rapid growth and reproduction is that access faeces are released in the Lagoon; these faeces contain organic material and sulphides which lead to the smothering, lack of oxygen and pollution in the sand beds. This makes the sand beds unsuitable to other species.

According to the studies conducted by Robinson and Griffiths (2002) a comparison was done to investigate the differences between Mytilus galloprovincialis invaded areas and non-invaded areas in Langebaan Lagoon highlighting the effect it has on naturally-occurring communities. Communities in invaded areas differed more importantly from non-invaded areas because the figures were indicating that naturally occurring sandbank communities were being replaced with communities more typical of rocky coasts. To conserve the natural biota of the centre banks the mussel beds should be removed (Robinson and Griffiths 2002).

Mytilus galloprovincialis has not yet completely replaced Perna perna. Since Perna perna occupies the lower shore and Mytilus galloprovincialis occupies the higher shore. It can be concluded through the experiment by Shea and Chesson (2002) that M. galloprovincialis suffers high mortality due to wave action on the low shore especially in monospecific beds. In the absence of strong wave P. perna exclude M. galloprovincialis completely.
Though it is the most dominant mussel species today its introduction has not caused major extinction in South African marine species as compared to other invasive species and it has been widely beneficial as food.

Reference list


Branch, G. M. and Stephani, C. N. (2004). Spatial comparisons of populations of an indigenous limpet Scutellastra argenvillei and an alien mussel Mytilus galloprovincialis along a gradient of wave energy. [Internet]. 22 January 2007, 14:04 UTC [Cited 22 Jan 2007]. Available From:
http://www.nisc.co.za/oneAbstract?absId=993

Department of Environmental Affairs ad Tourism. (1999). Driving forces affecting marine and coastal systems and resources. [Internet]. 23 January 2007, 09:44 UTC [Cited 23 Jan 2007]. Available From:
http://www.ngo.grida.no/soesa/nsoer/issues/coast/driver.htm

Griffiths, C. L. and Robinson, T. B. (2003). Status and Impacts of Marine Alien Species in South Africa. [Internet]. 23 January 2007, 11:42 UTC [Cited 23 Jan 2007]. Available From:
http://www.sgnis.org/publicat/grifrobi.htm

Shea and Chesson, 2002. Community ecology theory as a framework for biological invasion, [Internet]. 22 January 2007, 08:16 UTC [Cited 22 Jan 2007]. Available From:
http://eprints.ru.ac.za/466/01/McQuaid_Will_the_invasive_mussel_Mytilus_galloprovincialis_Lamarck.pdf


Dianah Nangammbi
Cilla CSIR
P.O. Box 395
Pretoria
0001
Tel: +27 12 841 2133
Cell: +27 73 121 3589
Email: dnangammbi@csir.co.za
http://wwwdianah.blogspot.com/

THE AFRICAN GREEN MONKEY

Cercopithecus aethiops is the species of the class mammalian and order primates. C. aethiops is also known as the vervet monkey. The vervet monkeys weigh between 2.7 kg and 8 kg. This species has a lifespan of 22 years. The vervet monkeys are abundant type of monkeys and found in the large part of Africa. In most cases, they are used as the laboratory animal for testing different drugs if they will work for a particular disease [Matthews and Brandt 2004].

The vervet monkeys live in different types of habitats and amongst human, they prefer to live in riverine woodlands. This animal species are omnivorous animals preferring grass for their diet. However, this species prefer grasses, they also feed on arthropods and small vertebrates like lizards, etc. in order to gain protein in their body [Cheney and Seyfarth 1982].

The movement of vervet monkey is the same in the trees and on the ground. They move quardropedally. The vervet monkey gives birth to one offspring and has a gestation period of twenty-two weeks. The social life of the vervet monkey is different among the males, females, and juvenile males and adult males. The females adult interact with their close relatives and they allow other females to take care of their infant. The juvenile males care for their siblings and adults males does not have interest in the infants [Cheney and Seyfarth 1982].

The vervet monkeys use different types of methods for communication, namely, vocal communication, visual communication and tactile communication. The vervet monkeys can use a vocal communication to alert their members about the predators. This species use visual communication for starring, penile display, head-bobbing etc. The tactile communication includes nose-to-nose greetings. The advantageous method of communication is the vocal method because every monkey can be alert even if the monkeys are not close to each other.

The African green monkey became invasive on the Island because of their cropraiding habitat. It was suggested that this species were introduced by the ships that were running the West African Slave trade. The species were favoured at its invasion because they were not disturbed by anything e.g predators. As a result, they multiplied.

REFERENCES:

Cheney, D.L. and Seyfarth, R.M. 1982. Recognition of Individuals within and Between Free-ranging Groups of Vervet Monkeys. American Zoologist Vol. 22, 519-526.

Matthews S. and Brandt K. 2004. Africa Invaded: The growing danger of invasive alien species Global Invasive Species Programme 2004. Available from: http://www.gisp.org/casestudies/showcasestudy.asp?id=96&MyMenuItem=casestudies&worldmap=&country=


Ms Evelyn Maleka
CILLA CSIR
P.O. Box 395
Pretoria,
0001
Tel: (012) 841 2133/2807
Fax: (012 )841 4405
Email: emaleka@csir.co.za
http://malekaevelyn.blogspot.com/

CORRECTION FOR CHAPTER 2

Chapter 2 of this course states "Australian aborigines arrived with the dingo and Polynesians brought pigs, taro, yams, and rats (as stowaways)" between 1500 and 1800 AD. This is factually incorrect (see below). All these introductions took place well before 1500 AD.

The time of the arrival of the first humans in Australia is uncertain (with widely different dates documented using various methods) but is generally accepted to be between 40 000 and 50 000 years before present. Radiocarbon dating has placed many sites at about 38000 BC (i.e. about 40 000 years before present). Thermoluninescence dated some sites in northern Australia to about 48000 BC (i.e. about 50 000 years before present) (1). The first settlers did not introduce the dingo to Australia (2). The dingo (Canis lupus ssp. dingo) is thought to have been introduced from South-east Asia between 3000 BC and 1000 AD by Austronesian traders (2, 3) during a theorized intensification of the hunter-gatherer lifestyle (1). The earliest dingo fossil evidence in Australia dates from about 1500 BC (i.e. the fossil is about 3 500 years old) (2).

Present Polynesian cultures are thought to have developed from the so-called Lapita culture that spread from New Guinea to Fiji, Samoa and Tonga around 1600-1200 BC (4). This ancestral Polynesian culture had pigs, dogs and chickens which they took with them. Crops included taro and yams. The Polynesian rat was probably involuntarily spread by the Lapita peoples (5).

References

(1) Wikipedia contributors. Indigenous Australians [Internet]. Wikipedia, The Free Encyclopedia; Updated 2006 Oct. 5, 04:07 UTC [cited 2006 Oct. 5]. Avaliable from: http://en.wikipedia.org/w/index.php?title=Indigenous_Australians&oldid=79588443.

(2) Wikipedia contributors. Dingo [Internet]. Wikipedia, The Free Encyclopedia; Updated 2006 Oct. 2, 15:04 UTC [cited 2006 Oct. 5]. Avaliable from: http://en.wikipedia.org/w/index.php?title=Dingo&oldid=79048433.

(3) Corbett, L.K. Canis lupus ssp. dingo [Internet]. IUCN 2006, 2006 IUCN Red List of Threatened Species <http://www.iucnredlist.org/>; Updated 2004 [cited 2006 Oct. 5]. Available from: http://www.iucnredlist.org/search/details.php/41585/all.

(4) Wikipedia contributors. Polynesia [Internet]. Wikipedia, The Free Encyclopedia; Updated 2006 Oct. 3, 18:50 UTC [cited 2006 Oct. 6]. Avaliable from: http://en.wikipedia.org/w/index.php?title=Polynesia&oldid=79297561.

(5) Wikipedia contributors. Lapita [Internet]. Wikipedia, The Free Encyclopedia; Updated 2006 Sept. 18, 08:07 UTC [cited 2006 Oct. 6]. Avaliable from: http://en.wikipedia.org/w/index.php?title=Lapita&oldid=76374895.

ROBINSON et al. (2005) MARINE ALIEN SPECIES OF SOUTH AFRICA

This paper reviews the status of the Marine alien species from the South African coast, and hi-lights the ecological impacts of the alien invasions. The paper also includes for the first time what are known as “Cryptogenic” species, or species seldom seen or observed which are invasive.

This important paper indicates that marine organisms have been both intentionally and accidentally moved all over the world’s oceans since the first navigation of the seas and more specifically the increase in shipping over the last century. This includes the increased use of ballast water by ships, and the dumping thereof in different locations other than the original collection point.

Robinson et al. (2005) directed a survey of the present status of three invasive species that were last assessed 10 years ago. The European shore crab, Carcinus maenas, the Mediterranean mussel, Mytilus galloprovincialis, and the Australian whelk, Bedeva paivae were surveyed.

European shore crabs were first discovered in Table Bay Harbour in 1983, and Robinson et al. (2005) suggest that a previous study in 1990 proposed that the crabs “arrived via fouling of International oil exploration vessels, which had docked in the harbour since 1969.” Robinson et al. (2005) sampled both at intertidal and subtidal levels, and additional searches were implemented beyond the known range of the crab, but in similar appropriate habitat. Where populations were encountered in harbours, the size of the population was estimated using the mark-recapture method, which continued until the recapture rate of marked individuals was larger than 10%. No intertidal range extension for the European shore crab was documented, but the paper indicates the first discovery of this crab in the Hout Bay Harbour, which is further than what is previously suggested in my introductory article. The suggestion for the lack of crabs in intertidal areas, is that they may have difficulty in adapting to inhabitation of wave-exposed areas.

The Mark-recapture experiments indicated large subtidal populations in Table Bay Harbour (133 568 individuals) and Hout Bay Harbour (9180 individuals). It is suggested that the movement of small lobster-fishing vessels between these two harbours facilitated the invasion from the Table Bay Harbour to Hout Bay Harbour. What is interesting is that although subtidal sampling has been done for Saldanha Bay, Robinson et al. (2005) state that no specimens of Carcinus maenas were recorded. The authors indicate their curiosity for the apparent disappearance of Carcinus maenas from this area 12 years after its initial discovery and suggest that its potential for invasion could easily have disastrous impacts on the local biodiversity in Saldanha, however no suggestions are entertained regarding possibilities for their disappearance.

Was it biological? It is doubtful that it is physical since the habitat is very similar to that of Table Bay and Hout Bay, and Robinson et al. (2005) indicates a massive increase in their primary food source along the West coast, the invasive Mediterranean mussel, Mytilus galloprovincialis.

The authors conclude that Carcinus maenas is restricted to harbours and sheltered areas, though in general, the overall prevalence of alien marine species is lower than that of other parts of the world. One possible reason for these statistics is the lack of work that has been done in a predominantly unexplored region of the South Africa coastline where investigations for potential populations of alien species have not been carried out yet. The authors warn that another factor could be the relatively poor development of marine taxonomy, which is an additional limiting factor with only four full-time professional marine invertebrate taxonomists working in South Africa. It is suggested that the number and prevalence of marine invasive species will increase as more investigations are undertaken.

Reference:

Robinson T. B., Griffiths C. L., McQuaid C. D., Rius M. 2005. Marine Alien Species of South Africa - Status and Impacts. African Journal of Marine Science 27(1): 297 - 306.

David Vaughan
Senior aquarist, Quarantine
Two Oceans Aquarium
Cape Town, South Africa
dvaughan@aquarium.co.za