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15 July 2019


In July, I spent a week leading a postgraduate course in invasion science. Here's a piece that I wrote for the AC21 magazine (here), also posted on the CIB website (here).

Invasive species offer many important challenges to society. Their presence is intrinsically linked to human actions, but their impacts are felt across a wide range of environmental and socio-economic levels. Despite the severe impacts from invasions in past centuries, new introductions continue at an unprecedented rate and we require a new generation of invasion scientists to tackle the growing range of issues that invasive species bring. To this end, the Centre for Invasion Biology (C·I·B), with its hub at Stellenbosch University, organised the AC21 Postgraduate course: Invasions Science for society: hands-on experience of environmental, social and economic impacts of alien species. The course was designed to appeal to a wide range of participants from many backgrounds, whilst giving a uniquely African viewpoint on the issues around invasive species.

 Spectacular! The setting for the 2019 AC21 postgraduate course: Invasion Science for Society


The course took place within the breath-taking scenery of the Overberg, in South Africa’s global biodiversity hotspot: the Cape Floral Region. Although it took place in the height of winter, we enjoyed some marvellous weather, as well as a taste of Cape storms. The course also took advantage of the local environment to make outings getting a handle on the different local challenges from invasions.

The course took the form of a series of workshops conducted by C·I·B staff together with two invited international guest lecturers.

Prof John Wilson (C·I·B) challenged course participants to locate and neutralise an incursion of invading Australian Banksia ericifolia. This species had been introduced by flower growers, but after abandoning their farm, the species spread into nearby fynbos habitat. Despite removing nearly 300 individuals, the habitat still needs more follow up visits to ensure that the treatments have been effective.


Collecting data on the invasive Banksia ericifolia before removing them.

Dr Tammy Robinson (C·I·B) took the students to the local port town of Gansbaai to explain how marine invasions are transported through ocean going vessels. Large ships can carry invasive propagules in their ballast water, while smaller boats often carry invasive species as a result of hull fouling. Although these problems can be tackled through legislation, there are important economic impacts to be considered.


Dr Tammy Robinson shows students an invasive mussel attached to a kelp holdfast.

Prof Karen Esler (C·I·B) explained the complicated tasks of restoring local habitats after an invasion. After 10 years, the sites visited look considerably better, but still require a lot of attention before they can be considered as restored. Different invasive species leave different impacts on the invaded ecosystem, and this sometimes results in permanent impacts that can only be mitigated during the restoration process.


At a site of habitat restoration, AC21 students look at images of the site before it was restored 12 years ago, and learn about the need for continuing work.


Special guest lecturers, Prof Jana Fried (Coventry University, UK) and Prof Elizabeth Pienaar (University of Florida, USA) introduced AC21 participants to the role of social science and economics in invasive species. The students conducted a workshop to design a questionnaire to determine the socio-economic effects of invasive species, and then visited several locations in the area to ask people about how invasive species had impacted the lives of them, their households and their communities.


Workshopping the socio-economic roles of invasive species in society, above Prof Jana Fried (Coventry University) and below Prof Elizabeth Pienaar (University of Florida).

Dr Sabrina Kumschick (C·I·B) led a daylong workshop on how to make risk assessment for invasive species. In an innovative approach, students were broken up into groups to make assessments on fictional species, and then led discussions to imaginary stakeholder groups to determine the levels of potential conflicts for introducing the species.


Assessments were made to gauge the risk of some fictional characters so that the course participants could determine feedback from different stakeholders’ groups.

All participants in the AC21 post graduate course left South Africa with a much greater appreciation for the wicked problems involved in tackling invasive species. They return to counties across the globe to cast fresh eyes on the problems within their own communities, prepared with novel insights and a new suite of tools so that they can engage and work toward solutions. They also become alumni of the Centre for Invasion Biology (C·I·B), part of a growing network of invasion scientists from around the world.


Despite taking place in the midst of the Cape winter, the AC21 course had only smiles as they teamed up to take on the problems of invasive species.

  Lab  meetings

Nitya talks at Island Biology Conference

11 July 2019

Nitya talks at Island Biology 2019

Some of you may remember that Nitya won a prize for the best popular article at the CIB ARM back in November 2018 (see blog post here). The cash prize gave him enough money to attend an international meeting, of his choice. Nitya opted to attend the Island Biology 2019 meeting on Reunion. He managed to roll some other work into the trip, by joining the mascarene toad team on Mauritius (see blog post here).

Now Nitya is presenting his talk at the conference in the symposium: Future steps to fight against invasive species on islands.

I'm sure that it will be well received. 

Read more about Nitya and his PhD thesis research here. Read my blog about visiting the Andaman Islands here.

Mohanty, NP, Hui, C & Measey, J (2019) Invasion dynamics of an amphibian with frequent human-mediated translocations on the Andaman archipelago. Island Biology, La  LaRéunion 8-13 July 2019.

  Frogs  Lab  meetings

Tadpole anti-predator strategies

10 July 2019

What do tadpoles do when they sniff a predator?

Natasha Kruger asked this question of populations of the invasive African Clawed Frog in a study conducted with Jean Secondi in France. Clawed frogs have been invasive there for ~30 years, but a number of studies are suggesting that they have already started to adapt to the local conditions (see here). 

As an invasive frog, once you’ve been moved to the new environment, not only do you have to cope with new conditions, but your tadpoles do too. This means that tadpoles should be able to respond to new predators, as well as ones that they already know. This was the basis for the work that Natasha conducted on tadpoles of the invasive African clawed frog, Xenopus laevis, in France.

Natasha tested to see how tadpoles reacted to known and unknown predators. For example, she tried cues from aquatic snails and another invasive species in France, the red swamp crayfish, Procambarus clarkii.

Tadpoles were placed into fresh water in a cup with a cross drawn across the bottom. The cue was then dropped from above and their reaction filmed. She was particularly interested in the number of times that the tadpoles crossed the lines in the cup – showing a response to the cue.

Like other tadpoles, African clawed frogs were found to decrease their activity in the presence of a predator. That is they crossed the line less often when cues were given, compared to novel cues.

The early version of the manuscript is now up online and you can enjoy reading it here:

Kruger, N., Measey, J., Herrel, A., & Secondi, J. (in press) Anti-predator strategies of the invasive African clawed frog, Xenopus laevis, to native and invasive predators in western France. Aquatic Invasions

  Frogs  Lab  Xenopus

Submitted - Biological Invasions in South Africa

05 July 2019

Biological invasions in South Africa. Our book is written!

With 31 chapters and 104 contributing authors, our forthcoming book is going to be an epic tome. The book, now submitted, will be part of the Invading Nature - Springer Series in Invasion Ecology. It's been nearly a year since we made the proposal to the publisher to collect together as much information as possible on biological invasions in South Africa. Our approach was to be encyclopaedic, and so we inveigled as many of our colleagues involved invasion science as we could.

The book is divided into 7 parts:

  • Part 1: provides a broad overview of biological invasions in South Africa
  • Part 2: deals with the current situation
  • Part 3: details the underlying factors influencing invasions
  • Part 4: addresses why invasive species are important in the South African context
  • Part 5: covers aspects of the management of invasions in South Africa
  • Part 6: explores additional aspects relevant to biological invasions
  • Part 7: looks to the future of biological invasions in South Africa

Led by Brian van Wilgen, the book is edited by five Centre for Invasion Biology Core Team Members: Brian, Dave Richardson, John Wilson, Tsungai Zengeya and myself. It was no small task, but over countless meetings my fellow editors made it all an enjoyable experience. Brian kept us on track and generally cracked the whip.

Brian looks over his shoulder to make sure there are no large animals approaching

We look forward to the end of the year when we'll be able to offer everyone unlimited access to pdfs of all the chapters.

For those of you interested in my contribution, I led two chapters and contributed to six more (see details here).

Measey J, Hui C, Somers M (2019) Terrestrial vertebrate invasions in South Africa. In: van Wilgen BW, Measey J, Richardson DM, Wilson JR, van Wilgen BW (eds) Biological invasions in South Africa. Springer, Berlin. 

This is a review of the invasive terrestrial vertebrates in South Africa. It contains species acounts of 30 animals, and details their distributions and impacts. We aim to provide a useful perspective on the extent of current invasions within the country, as well as providing a resource for much of the research that has been conducted on them.

Measey J, Robinson TB, Kruger N, Zengeya TA, Hurley BP (2019) South Africa as a donor of alien animals to other parts of the world. In: van Wilgen BW, Measey J, Richardson DM, Wilson JR, van Wilgen BW (eds) Biological invasions in South Africa. Springer, Berlin

This is an unusual twist on the invasion paradigm as here we consider species native to South Africa which have invaded places in other parts of the world. For me, this chapter was quite an eye-opener as the more I read, the more species I found (and the longer the chapter grew). We finally ended with ~34 species with some really great stories from drug barons to the director of nature conservation; those responsible for introducing these species are a pretty maverick bunch.

Keep watching this space...


Tiny Toads meet their match on Mauritius

02 July 2019

Marauding Mauritius for Tiddly Toads

This month, the MeaseyLab has relocated to the Mascarene Islands of Mauritius and Reunion to conduct research on their invasions of Guttural Toads, Sclerophrys gutturalis. These toads were introduced, from the port city of Durban in South Africa, into Mauritius in 1922. Now, nearly 100 years later, they can be found nearly everywhere on the island. Intriguingly, they are a fraction of the size of the animals found in Durban. I visited Mauritius a while back (see blog post here), and worked with Claudia Baider and Vincent Florens to visit some toad populations in different parts of the island. Now the lab is back and working on the toads.


Carla has been seen with Guttural Toads before (see here and here), but this is her first time in Mauritius. Not only is she collecting faecal matter for her MSc on the Guttural Toad microbiome, but she’s using the opportunity to collect some skin swabs for our collaboration with Morne du Plessis at the National Zoological Garden, Pretoria (see here).


James only just started his post-doc in the MeaseyLab (see here). He’s using the model system of the Guttural Toad in Africa to understand their invasion success through the investigations of divergent phenotypic traits and rapid, localised evolution. Mauritius is his first field stop, and he’s making the most of every moment by putting the toads through their paces.


Nitya and Julia are helping out James and Carla with their work but adding their own research talents into the mix. We’ll come back to that in future when the publications start rolling out!


All together, the fab quartet make a talented team to take on the challenge of these invasive amphibians on Mauritius. You can be sure that those tiddly toads are no match for the four of them.


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