I am very lucky that I can meet experts in conservation on a regular basis. Sometimes I meet an expert who is not only knowledgeable, but is also enthusiastic, adventurous and a very cool person to hang out with. This is when I absolutely love my job.
Xander is the park’s expert on the thousands of other smaller species, especially snakes, lizards, frogs and toads.
I spent two days with Xander recently in the southern part of the park, near the town of St Lucia, where he lives with his wife Susan, and sons Stian (10), Anno (8) and Bernard (6).
iSimangaliso has all the typical large African wild animals, like elephant, white and black rhino, lion, wild dog, leopard and hippo, but what makes the park truly special is the thousands of other species, all crammed into a long, narrow stretch of north-eastern South Africa.
While Kruger, Serengeti and Chobe National Parks are deserved icons of Africa, parks like iSimangaliso are as valuable from a species conservation perspective. Read on a little, and it’ll become very clear.
From 2003 to 2008 Xander managed the park’s threatened species program. He was responsible for compiling species lists, especially for the rare and endemic animals, especially the thousands of lesser-known smaller species, including snakes, frogs, toads, butterflies, dragonflies and lizards.
From 2009 to 2012, Xander completed his PhD on the ecology of the Nile crocodile in Lake St Lucia (as part of iSimangaliso, the lake has the largest single population of crocodiles in the country). During his research, he spent most nights looking for crocodiles, catching more than three hundred of them to study them. In the process he covered almost every square metre of the lake and it’s shores. If anyone knows Lake St Lucia, or understands crocodile behaviour, it’s Xander.
Now he’s got the humble title of Support Technician, which really is an absurdly inappropriate name for what must be an important, fascinating and difficult job: Keeping track of all animal species in the park, among other things. Sound simple? Not really.
iSimangaliso, by some accurate estimates, has more species of animals per square kilometre than any other protected area in Africa.
Only people like Xander could do this job successfully. He has a fascination for every frog, snake, lizard, butterfly and dragonfly he sees.
For a few nights Xander, his three sons and I went looking for frogs and snakes. On the first night as we drove through the southern section of the park, we came across a snake in the road. Xander hit the brakes and jumped out the car, picking up the snake before it slithered away. It was a rhombic egg-eater – not unduly rare – but he was so excited to show me the snake that I figured he had won the lottery!
Because there are so many species of animals in iSimangaliso, there’s plenty to talk about. And Xander is more than happy to do so!
“The 3 300 square kilometre iSimangaliso is just so special,” Xander started off. “Despite being only 3 300 square kilometres compared to Kruger’s 20 000 square kilometres, iSimangaliso as 118 reptile species (KNP 112), 62 snake species (KNP 54), 49 amphibian species (KNP 46).”
“So, even though iSimangaliso makes up just 0,3 per cent of South Africa’s surface area, we have 53.4 % of all the described snake species in RSA, Lesotho and Swaziland, 30.8% of all the described reptile species and 41.5% of all frogs and toads in the region.”
“Among other taxonomic groups, there are also 228 spider species, 139 dung beetles, 282 butterflies, 526 birds, 129 species of coral, 812 marine molluscs, 991 ocean fish, 48 fresh water fish and 325 species of seaweed! We have extremely diverse terrestrial, fresh water and marine environments.”
“This really is a biodiversity hotspot, with a disproportionate number of species, making it extremely valuable. If you want to put conservation money into a particular area, then you want to protect the most possible species. iSimangaliso is THAT place in the country.”
I asked Xander a few questions about iSimangaliso.
Scott Ramsay: What makes the park so diverse?
Xander Combrink: There are four main things: geology, topography, climate and habitat.
First, geology. The park is at the southern tip of the Mozambique Coastal Plain with very sandy, deep soils. These are poor in nutrients, yet provide the geological base for rich coastal forests. Then there’s a huge mosaic of wetlands. You don’t find this anywhere else in the country.
From here this geology doesn’t extend far south or inland, probably only about 50kms, but as you go north into Mozambique it veers out far into the west, and ends in Kenya.
Because of this unique geology, we find things like the East African egg-eater snake. iSimangaliso is the most southern distribution point in Africa. You find them all the way to Kenya but not further south of here.
A lot of the park’s species are like that. If you look at the distribution maps in reptilian field guides, you’ll see the north-eastern corner of South Africa has many of the same species as Mozambique or Kenya.
Second, climate. This is a transitional zone between tropical, sub-tropical and temperate climates.
We have species in iSimangaliso that are found in cooler climates further south, which have their northern-most distribution in iSimangaliso. And we have many tropical species which have their southern-most distribution in the park. We’re at an important interface here. The warm, tropical Agulhas sea current which pushes strongly from the north has a massive effect on climate of course.
The rainfall gradient is drastic. From about 1,200mm on the coastal dunes, rainfall drops to about 700mm on the Western Shores within a distance of just five kilometres.
One of the most incredible things about iSimangaliso is the huge variance or flux that we have in climate very year. We can have a drought one year and then periods of floods, so there’s very seldom an average year of anything. Things are always moving up and down.
Third, topography. There’s a huge altitudinal gradient from 1 200 metres on top of the Lebombo Mountains in the west, right down to the coast in the east. This world heritage site covers the whole spectrum.
Fourth, the previous three things influence the habitat. And the diversity of habitat is just incredible.
Mountainous terrain, sand and fig forests, almost 300kms of uninterrupted coastal dune forest, a huge mosaic of wetlands, grasslands, bushveld, coral reefs and deep ocean canyons with remarkable fish like the Coelacanth.
In the south is Lake St Lucia, the largest estuarine system on the whole African continent! In the north of the park, Lake Sibaya is the largest freshwater lake in South Africa, and the four interconnected lakes at Kosi is unparalleled.
So the park has three of the largest natural lakes in Southern Africa. That’s immensely valuable. Some species like the Sibaya Goby fish are only found in Kosi and Lake Sibaya, and nowhere else.
SR: And then there’s the link between fresh water and sea water, right?
XC: Yes, a huge driver of diversity is the varying levels of salinity in the lakes, which are connected to the ocean via the estuaries. We have fresh water flowing into the lakes from rivers, but during droughts the salinity reaches about 200 parts per thousand sometimes. That’s beyond hyper-saline if you think that sea water is only 35 parts per thousand!
Over 80 parts per 1,000 and only the tilapia fish survive. All the benthic species are supposed to die out, but there is remarkable resilience. In 2006, about 90% of Lake St Lucia was dry and it had a huge impact on the abundance and the density of everything.
Now, three years down the line, we have seen massive re-colonisation of all the species. It’s incredible how they come back. You just wonder where they were?
These extreme events are important because they drive the diversity. Species are forced to adapt during all the flux. And so, for example, the tilapia in Lake St Lucia breed at higher salinities than anywhere else around the world.
During droughts, fresh water from the coastal dunes seeps into the sea. I’ve never seen it, but scuba divers tell me that there are spots where you can physically see the fresh water oozing through the sand.
Some marine fish species go to these spots of fresh water to rid themselves of ecto-parasites. I don’t know how much of that’s been published scientifically but certainly it’s been postulated.
SR: The whole ecological system seems very resilient?
XC: Yes, for instance, on the edge of Lake St Lucia there are massive swamp forest areas, and during droughts the fresh water seeps from the forests into the lake, so the lake shore turns lush and green, even though there’s a drought. Although the lake itself had no water in it, there was this small pocket of fresh water in the adjacent swamp forest.
I researched a female crocodile once with a transmitter, and during the drought of several years, she stayed within an area as big as a garage. She had enough food, probably bush pigs, duiker and bush buck that would come down to drink, because there was no other water around.
She mated successfully every year, which goes against most of our previous research about croc behaviour during a drought in St Lucia. So despite the dry conditions, this little pocket of fresh water made her very happy, and she was able to not only survive, but thrive.
So these pockets of resilience and variety of habitats drive diversity, and this is what makes iSimangaliso special.
Check out my next blog on Xander as he shows me some of the beautiful frogs of iSimangaliso.