The recent tragic death of more than 300 African elephants in the Okavango delta region of Botswana, a country in Southern Africa, has brought attention to a global concern: the presence of neurotoxins in water produced by cyanobacteria. Neurotoxins are substances that can damage, destroy, or impair the functioning of neural tissue.
About Cyanobacteria
Cyanobacteria, also known as blue-green algae, are microscopic organisms found naturally in soils and all types of water. They are single-celled bacteria living in fresh, brackish (combined salt and freshwater), and marine water. These organisms utilize sunlight to create food and are capable of multiplying rapidly in warm, nutrient-rich environments high in phosphorus and nitrogen. Although not all cyanobacteria produce toxins, the ones that do are becoming increasingly prevalent due to the temperature increases associated with climate change.
Climate Change and Algal Bloom
Algal bloom refers to the rapid multiplication of algae or cyanobacteria in an aquatic environment. Several factors related to climate change contribute to this phenomenon.
Toxic blue-green algae prosper in warm, slow-moving water. With global warming, water temperatures are on the rise, creating favorable conditions for harmful algae. Warmer temperatures prevent water from mixing, which in turn allows the algae to grow thicker and faster.
Apart from temperature, changes in salinity due to climate change-induced droughts make freshwater saltier causing marine algae to invade freshwater ecosystems. Rising carbon dioxide levels – both in the air and water – are another contributing factor. The increased carbon dioxide encourages rapid growth of algae, particularly toxic blue-green algae.
Another contributing factor is the altered rainfall patterns because of climate change. This can lead to alternating periods of drought and intense storms, causing more nutrient runoff into water bodies and thus feeding more algal blooms.
The African Elephant
The African elephant, the largest land animal on Earth, roams 37 countries in Africa. Unfortunately, its status is currently listed as vulnerable by the International Union for Conservation of Nature (IUCN) Red List. The African elephants residing in Botswana, Namibia, South Africa, and Zimbabwe are included in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II. This list includes species that are not necessarily threatened with extinction but need controlled trade to ensure survival.
African elephants have two subspecies: the Savanna (or bush) elephant and the Forest elephant. Interestingly, the forest elephants are a distinct subspecies uniquely adapted to the forest habitat of the Congo Basin. However, they are in sharp decline due to poaching for the international ivory trade.
In order to raise awareness about the conservation and protection of these magnificent creatures, World Elephant Day is celebrated every year on August 12.
About Botswana
Botswana is a landlocked country in southern Africa, characterized by flat topography with a few hills along the southeastern section of the country, on the eastern edge of the Kalahari Basin. The semi-arid Kalahari Desert, despite receiving about 500 mm of rainfall in the wettest parts, covers about 70% of Botswana’s surface and is still considered a desert due to its vast sandy surface.
Botswana is a biodiversity hotspot, home to various plant and animal species. Indigenous people, including the San people (Bushmen), Tswana, Kgalakgadi, and Herero people, also call Botswana their home.
The Okavango Delta, one of the world’s largest inland deltas, covers about 15,000 square kilometres of Botswana and is characterized by its relatively flat topography.
