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Decreasing water levels of Lake Tanganyika Affecting Fishing activities

Lakes in the tropical region of East Africa don’t capture a lot of attention as they are being affected by climate change because the effects may not be as visible as for example melting of snow in the polar regions of the world. One significant effect of climate change is the rising surface water temperature of the lake common to many lakes in the world. This effect has a great impact on the ecosystem of the lake which threatens its life.

As predicted by the climate scenarios that the air temperature is likely to increase between 2-5 degree Celsius in the next 50-100 years, the temperature of most lakes is also likely to warm and therefore,the current temperature increase would serve as an early warning for the world to act. Lake Tanganyika is one of the Great Lakes in Africa and its considered to be the second largest in the world by water volumes and second deepest behind Lake Baikal in Russia.

Lake Tanganyika contains 17% of the world’s surface fresh water which is an approximation of almost all the combined five North American lakes.

The natural vegetation around the lake has been removed through deforestation and this has put the life of the lake at stake because of the erosion of particles and nutrients into the lake which brings about eutrophication.

Deforestation around Lake Tanganyika leading to erosion of nutrients towards the lake
Deforestation around Lake Tanganyika leading to erosion of nutrients towards the lake

Warming of Lake Tanganyika

The waters of Lake Tanganyika are warming by 0.1 degrees Celsius every decade and have warmed by 1 degree Celsius in the past 100 years. This temperature has led to almost a 20% reduction in biological productivity of the lake as well as affecting the lake’s ecosystem. This has had a direct impact on the fish catch which is an economic activity supporting a number of people around the lake on top of clean water for drinking. Recent studies have revealed that the lake’s warming rates are consistent with other lakes in the world.

Studies have also revealed that surface water is warming more rapidly than its depth and this has led to stratification of the cool and warm waters. This has reduced the circulation of nutrients in the surface warm water.

Lake Tanganyika has one of the longest temperature records than any other lake in the world. Scientists began measuring temperatures of the lake at 1,000 meters deep a century ago using specialized thermometers. More temperature studies were made since 1920s,1940s,1970s and more regular in 2000s.With the current developed trends in technology, sophisticated instruments are used to measure the temperature of the lake waters up to the bottom of the lake and according to the current records, scientists state that the surface waters of Lake Tanganyika are warming at a very rapid rate than its depth. This creates a big temperature difference that wind induced mixing of the surface and deeper waters is not good enough.

Scientists state that the energy required to maintain mixing of the warm water and the cooler waters of Lake Tanganyika is huge,therefore,there is a challenge in circulating the nutrients with in the lake. With too little nutrients therefore, the lake cannot support aquatic life and with too high nutrients the lake becomes over productive therefore developing algal blooms and weed growth which are dangerous to the life of the lake.

One surprising characteristic of Lake Tanganyika is that its surface water has fewer nutrients and yet it supports a very productive fishery. This is attributed to the occasional up welling of the nutrient rich waters from the bottom to the surface of the water.

Effects of nutrient levels on the surface water of Lake Tanganyika
Effects of nutrient levels on the surface water of Lake Tanganyika

However, decreasing up welling of the bottom water has been noted and this is related to climate change. Therefore, the productivity of the lake has put the aquatic life in danger and hence changing the ecosystem of the entire lake.

More scientific research is therefore needed to further understand the warming of waters of Lake Tanganyika and how its ecosystem is being affected generally, otherwise we may gradually lose one of the great lakes in East Africa and Africa and at large.

What has been done?

In 2012, the four countries surrounding Lake Tanganyika met in their body called Convention on the Sustainable Management of Lake Tanganyika to discuss their commitment to save the nature of the lake. They also pledged a fundraising campaign to raise funds for the conservation of the natural ecosystem of the lake.

The recognition of the impact of warming climate on Lake Tanganyika, forced The Nature Conservancy (TNC) to launch a project in 2012 in collaboration with locals and international bodies to establish climate change adaptation strategies and actions in Lake Tanganyika region. The project was referred to as “Tungane” a Swahili word meaning Let’s unite. This project was based on a participatory action involving empowering of the local people around the lake to sustainably manage their lake. The actions on the lake do not involve radical departures of the actions people are doing to improve their livelihoods but involve other wide adaptation strategies such as implementing village land use plans, improving fisheries practices, and limiting further habitat destruction among others. With these actions in place and the people recognizing climate change, the natural ecosystem of Lake Tanganyika will be saved

Low fish productivity since 1950s on Lake Tanganyika have been attributed to Climate Change not just over fishing.laketanganyi