Alkaline Tilapia - Life Is All About Balance!

Life in the natural world is always in the balance, animals are forever calculating the risk of a task verse the reward. For instance predators attempting to take down large prey have to face the risks that they could become injured attempting to bring down their prey whilst if they succeed they gain a large reward which will sustain them for a longer time. Whilst on the other side of the scale herbivores have to weigh up the time they spend feeding verses the time they spend looking for predators.

In some cases the risks can be almost constant and extreme while the reward is simple surviving; this is the case for the Alkaline Tilapia. This fish which is found in Lake Natron in Arusha Tanzania and inhabits one of the more extreme aquatic environments found on this planet. Lake Natron is a salt and soda lake which often has temperatures which exceed 40⁰C and due to its high levels of evaporation a pH greater than 12 so hence the fish’s name.

The scientific name of this Tilapia is Alcolapia alcalica and it is part of the Cichlidae family which has 2,000-3,000 individual species in and can be found in lakes across Africa. These fish have evolved over time to be able to cope with these extreme environments which are found in the lakes, but even they have to run the risks the lakes can posse daily. As well as the high levels of salinity found in the lake which is a problem in itself they also have to cope with the many hot springs which release water into the lake and sustain it, sometimes these springs temperature can exceed temperatures above boiling.

These springs are important for the Tilapia as they input nutrients into the lake and so large algal blooms grow round them and this is what the Tilapia feed on. These springs also mark the area of risk which the Tilapias have to face. They need to get close enough to the springs to feed on the algae but can only remain close to the springs for a few seconds before retreating to cooler water so as not to be boiling alive.

So the risk is death while the reward is life when it ‘boils’ down to it. The risks can vary though, the nearer to the spring the greater the algal growth so the pay of is better  with individuals which venture further towards the springs being stronger and in better condition but if they get the timings wrong it's game over. But this is something that the fish have to face daily.  

The Tilapia isn’t the only species which inhabits Lake Natron however it is also famously the breeding ground for 2.5 million lesser flamingos (and this is probably where you've heard of it before). These flamingos benefit from the lake as it provides a secure environment to raise their chicks safely away from predators whilst they have to grow thick scales on their legs so as to avoid alkaline burns from the water.

Thanks for reading!

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