SA team deployed to eradicate 'aggressive' alien

2014-09-09 09:05
An eradication team clearing an infected area on Gough Island. (Photo: Peter Ryan)

An eradication team clearing an infected area on Gough Island. (Photo: Peter Ryan)

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Cape Town – A South African eradication team has been deployed to Gough Island to target a seemingly modest, yet devastating invasive alien plant.

Team leader and UCT researcher Prof Peter Ryan says Sagina procumbens has already completely taken over the Marion and Prince Edward Islands.

“It’s a tiny plant that can grow into a modest cushion, but the scary thing is that it has the ability to displace native vegetation,” Ryan told News24 at the farewell ceremony for the SA Agulhas II.

The research vessel left for Gough Islands on Thursday 4 September and will arrive early this week. The vessel is taking an over-wintering team and will also conduct a variety of studies en route to the island.

According Ryan Sagina, which is also called the Procumbent Pearlwort, is problematic because it grows very fast and produces seed quickly, many of which can survive for over 100 years.

“The worry is that if it gets up into the highlands, it will takeover – at Marion it is displacing native species and invertebrates,” he said.

Sagina is native to Europe and is listed as one of the “One Hundred of the World’s Worst Invasive alien species".


According to the Department of Environmental Affairs the eradication programme started in 2000 and involves mechanical removal, treatment with boiling water, chemical herbicides, pre-emergent seed killers and direct heating of rock crevices to kill the seeds.

Ryan, who has been working on Gough intermittently for the last 30 years, says that Sagina most likely came to Gough from Marion Island by ‘hitch-hiking’ on shipping containers.

Extensive mats of Sagina on Prince Edward Island (Photo: Peter Ryan)

“Prior to the early 1990s all the stuff that went to the island went in little wooden boxes of which new ones were built each year and burned afterwards. After this reusable containers were introduced to reduce wastage and they were moved from one island to another.”

Council for Scientific and Industrial Research invasion biologist, Ryan Blanchard, says alien invasive species are included within the top drivers of biodiversity loss worldwide and leads to increasing environmental degradation.

“To reduce these negative impacts, the cost of removing invasive species can exceed millions of US dollars presenting a serious challenge to governments worldwide,” Blanchard told News24.

According to Blanchard climate change may also play an increasingly important role in the transformation caused by invasives.

“Climate change may provide the optimum conditions needed for these species to spread and become problematic where they are currently not - the success of future invaders may be driven by changing climates,” he said.

Prof Ryan, who will spend five weeks at Gough, also lamented the threat of climate change saying “non-aggressive invasives will become more aggressive”, and added that Islands are very susceptible to invasion.

Team leader and UCT researcher Prof Peter Ryan before the trip (Kelly Anderson, News24)

Yet, he hopes that through eradication programmes like these “there will be little corners of the world that won’t become ‘McDonaldised’ by tramp species eroding our biodiversity”.

- Follow Dane on Twitter

Read more on:    cape town  |  environment  |  conservation

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