SAIAB trip on the Krom

19 January 2018

Invasive fish on the Krom

I spent a couple of days with Olaf Weyl's group on the Krom River, Cederberg, prior to the extirpation of invasive fish. Olaf's group has been monitoring the Krom for 2 years prior to the removal of alien fish by CapeNature. The trip was organised to train Honours students from all over South Africa by Olaf's post-graduate experts.

This stunning locality has invasive trout, bass and bluegills. The monitoring consists of assessments of current fish stocks before the extirpation. Olaf's group uses GoPro cameras, snorkling swim counts and fyke nets to assess current fish abundance. Once the Krom has been treated they will be able to track its recovery. 

Thanks to Olaf's group for organising the trip.

  Frogs  Lab

Am Nat paper on Capensibufo published

20 December 2017

Our Capensibufo paper is published in Am Nat

This amazing paper came about during the Honours thesis of Francois Becker when he studied the 7 years of CMR data that we had accumulated on Capensibufo rosei. What Francois found astounded us all, that the survival of these toads was correlated extremely well with rainfall during the breeding period.

Here's the graph that we found so amazing. Survival probability varies between 0.04 and 0.92, and 94% of this variation was explained by variation in breeding-season rainfall. This result seemed completely counter-intuitive. Surely during a period with good rainfall we'd expect animals to do well? The answer we suspect is that they do so well, sitting out in the puddles during the wet weather, that they lose condition and don't make it through to breed the next year. Conversely, in a dry year, the animals don't spend long in their puddles and so go back to ground very early.

In this video clip, you can see some of the amazing scenes from mating behaviour of this species.

We now know that these animals are endemic to the Cape peninsula, but suspect that the other species all have similar life-histories. 


INVAXEN informs EU policy

15 December 2017

How does research get translated into policy?

Work on invasive Xenopus laevis by a consortium of labs in Belgium, France, Germany, Portugal and South Africa has produced research that helped to brief European policy makers.

“According to our research, climate change could increase invasion risk of predatory frogs such as the African clawed frogs. Areas in France and the UK are particularly vulnerable to invasions because of their increasing suitability as a habitat with warming temperatures. This situation requires priority setting and better anticipation of future invasions.” Anthony Herrel, coordinator for the BiodivERsA-funded project INVAXEN.

The policy brief above features the MeaseyLab publication: Frog eat frog.

  Frogs  Xenopus

What if your lifespan was linked to the weather?

15 November 2017

Live for the day—or maybe longer depending on the weather! 

Blue whales live for more than 100 years, while adult mayflies may come and go in a day. Our own lifespan has increased by nearly 10 years over the past generation. We are used to a world where the life expectancy of animals is expected to vary by a few years, but what if your lifespan was linked to the weather? Researchers from University of Cape Town, South African National Biodiversity Institute, and Stellenbosch University have discovered a frog whose likelihood of survival appears to be linked to the amount of winter rainfall in South Africa’s biodiverse fynbos biome.

Rose’s mountain toadlet comes out every winter to breed, but the amount of time the males spend waiting in puddles for females to arrive influences life-expectancy of these tiny toadlets. At only 20-30 mm long, these voiceless toadlets are easily overlooked, but the researchers, Francois Becker, John Measey, Krystal Tolley, and Res Altwegg, undertook a mark-recapture study over 7 years, to reach the finding that whether toadlets live long (4+ years), or just one year, depends on the weather.

Surprisingly, ‘good weather’ for frogs (wet winters) was found to reduce survival as animals are thought to spend more time out in the open, while ‘bad weather’ (drier winters) means they abandon the breeding site quicker, resulting in these toadlets living to try again another winter.

The correlation between survival and winter rainfall is truly remarkable, but the exact mechanism determining survival needs more work, and time is running out. The latest IUCN assessment is that this species is Critically Endangered and with climate in the area changing, it could be that changes in the winter rainfall regime could add to existing threats for this special species.

While this is the first known example of a vertebrate with extreme changes in survival that appear to be weather dependent, it may simply be due to a lack of sufficient research on the world’s smaller animal species. The researchers suggest that this kind of weather induced longevity change may be far more common than we are aware, prompting more concern about how changes to the climate may affect wildlife.

Read more about it here at American Naturalist


CIB Annual Research Meeting - Natasha takes a prize

10 November 2017

The 13th Annual Research Meeting of the CIB - Congratulations Natasha!

The 13th Annual Research Meeting of the CIB took place at Stellenbosch University Thursday and Friday.

Presentations were made by Nitya, Natasha and Marike.

From top right:

1. The judges receive their thank you presents from Dave Richardson: Piero Genovesi, Laura Meyerson, Petr Pyšek & Tim Blackburn.

2. Marike answers a question from the audience (and who was part of the winning pod)

3. Natasha gives the talk that won her best runner up for a PhD presentation

4. Nitya wows the audience with the size of his bullfrog. 

Well done to the whole lab who put on a magnificent set of froggy presentations. Especially well done to Natasha!

  aSCR  Frogs  Lab  meetings  prizes  Xenopus