East Africa’s ‘soda lake’ is rising, threatening its iconic flamingos

A flock of millions of giant pink flamingos, their flames are one of nature’s great wonders. But my colleagues and I found a worrying trend in the salty and highly alkaline “soda lakes” in East Africa where most of the birds live.

Lesser flamingos are the most abundant of the six species of flamingos found around the world, with more than three-quarters found in soda lakes in Kenya, Tanzania and Ethiopia. Although the population is estimated to be between 2 million and 3 million, the species is in decline and is officially listed as “near threatened.”

Due to the remote location of many soda lakes and the nomadic nature of the birds, the cause of population declines is difficult to determine. They often fly between soda lakes at night in search of new feeding spots in response to the boom-and-bust nature of the cyanobacteria (commonly known as blue-green algae) that they feed on.

However, rising water levels in many feeding lakes are decimating the cyanobacteria that birds have evolved to eat.The research has now been published in the journal modern biologyMy colleagues and I found that only half of the lakes that provided high-quality feeding habitat in 2000 were still suitable for feeding in 2022.

Lesser flamingos feed by turning their heads upside down, pumping water into fine hair-like structures called lamellae in their beaks, and catching only cyanobacteria of a certain size. This highly specialized strategy means birds rely heavily on certain cyanobacteria, such as spirulina.

This is the same vitamin-rich spirulina you see in smoothies or supplements. In nature, the species that flamingos eat only grows in highly salty and alkaline conditions, but in soda lakes it is so abundant that these lakes are among the most productive ecosystems on Earth.

But these lakes are particularly sensitive to change because they typically have no outflowing rivers. As water levels rise, they become diluted, reducing salinity and alkalinity and limiting the growth of cyanobacteria that flamingos need to survive.

Drink more water and eat less

To assess threats to lesser flamingos, we used satellites to monitor 22 major feeding lakes in Ethiopia, Kenya and Tanzania between 1999 and 2022. monitor.

Kenya and Tanzania have seen the largest rises in water levels in recent years, particularly the historically important flamingo lakes Bogoria and Nakuru, which recently supported more than 1 million flamingos .

However, between 2009 and 2022, Nakuru’s size nearly doubled, while the average concentration of chlorophyll a (a photosynthetic pigment measured through satellites that can be used to estimate the presence of cyanobacteria) halved. Bird populations have significantly declined due to reduced food sources.

Lake Natron in Tanzania is also worth mentioning as it is the only regular breeding site for the Lesser Flamingo in East Africa. Therefore, rising Natron water levels and reduced food sources threaten not only current population numbers, but also the birds’ ability to breed in the area, potentially leading to sharp population declines in the future.

The rise in water levels is likely due to increased rainfall and deforestation in recent decades, which has caused rainfall to flow directly into the lake. Rainfall in East Africa is expected to increase as climate changes, driving lake levels to rise further in the future.

At least for flamingos, it’s not all bad news. Six of the 22 lakes provided more suitable habitat for flamingos in 2022 than in 2000. However, many lakes do not receive the same international protection because there is no history of flamingos living there.

It’s not just flamingos that are at risk. Soda Lake contains plants and animals found nowhere else on Earth, including fish, invertebrates, and phytoplankton. The decline of one of the most charismatic of birds offers an insight into what might be going on beneath the surface.

These lakes could serve as early beacons of how climate change is affecting inland waters around the world. If we want to protect these highly fragile ecosystems and their iconic pink birds, we must take action to mitigate the region’s increasing rainfall.

We need to know what’s happening on the ground and where the flamingos are going, so more regular water quality monitoring and bird counts are needed in Soda Lake. We also need to protect forests near lakes that are most susceptible to change, and restore degraded lake watersheds. This will reduce the amount of rainwater flowing directly into the lake and give cyanobacteria a fighting chance.

With the right help, the spectacular flamingos will continue to grace East Africa’s lakes into the future.

This article is republished from The Conversation under a Creative Commons license. Read the original article.