Over the last three years with my association with Magnetic South and the African Otter Trail Run I have tried to highlight and create greater awareness around the importance of the Tsitsikamma Marine Protected Area. Just a reminder, the entire marathon distance that you run along the Otter trail, you are in fact running next to one of the largest, and certainly the oldest Marine Protected Area in Africa.
Those of you who have already completed an Otter event will have heard me speak about the endemic and resident fish that the MPA protects. But marine protected areas go beyond the protection of fish populations. By protecting habitats we are protecting all organisms. This is important in that it allows natural ecosystem functioning. Which basically means things can work the way they should. And if things are working the way they should then we benefit via the goods and services that flow from these functioning ecosystems.
One of my colleagues in South African National Parks has been running a project looking at the abundance and sizes of different rocky intertidal bait organisms for the past few years. He wanted to see if the MPA was having an impact on the number and size of those organisms usually collected by humans for either fishing or consumption.
The results of his experiment have shown that red bait, which is frequently collected by fishermen, is almost three times more abundant in the park and the average size is almost three cm larger. As expected mussels were more abundant in the park and although alikreukel were rare the overall density in the park was double that outside. However, both siffie and the Cape urchin are more abundant outside the park in areas where bait collecting occurs. Sea urchins are algal grazers and some studies on the west coast have shown that Cape urchin numbers increase when predation pressure and competition decrease. It has also been shown that juvenile abalone (related to the siffie) shelter under sea urchins gaining protection from predation and increasing survival rates. So there could be a direct relation between the increase in Cape urchins and siffie within the exploited sites.
Ultimately, this work adds to growing body of research that highlights the benefits of Marine Protected Areas for biodiversity conservation. So remember as you run, trundle, bumble, stagger and climb your way along the Otter trail that just next door to you is a thriving healthy marine ecosystem from the mussels on the shores to the fish in the sea.
Kyle Smith – Marine Ecologist