Lake Nakuru: Flamingo death camp
Thousands of birds are dying at the saline water lake due to heavy pollution and receding water levels, write MICHAEL NJUGUNA and OLIVIA OWUORHeavy pollution and the destruction of the Mau Forest are responsible for the deaths of over 20,000 flamingos at Lake Nakuru National Park, in the last three months.
And in what has scientists baffled, over 800,000 of the estimated 1.3 million flamingos have moved from the saline Lake Nakuru to other water bodies, such as the fresh water Lake Naivasha. Lake Naivasha is currently hosting about 40,000 of the birds.
According to Mr Apollo Kariuki, a senior research scientist at the park, small flocks of flamingos sometimes visit Oloiden and Somachi within the Crater Lake, but large congregations have not been witnessed in the fresh waters of Lake Naivasha as is the present case.
Studies done elsewhere in the world have shown that migratory birds have dramatically changed their habits to cope mainly with global warming.
Following the deaths of the birds in Nakuru that began in June, experts from the Kenya Wildlife Service and the Veterinary Department took 49 samples of the dead birds for testing at the Central Laboratory at Kabete.
A week ago, the Rift Valley provincial director of veterinary services, Dr Geoffrey Mutai, said results from the samples indicated the birds die from a bacterial infection.
The bacteria Pseudomonas aeruginosa is said to cause disease in susceptible hosts, including human beings. It attacks hosts with already weakened immune systems.
Kariuki and an assistant director of veterinary services, Dr Michael Cheruiyot, said the organism’s concentration increases in areas where water levels are rescinding just as is happening IN Lake Nakuru.
This finding is the first concrete scientific evidence that the destruction of water catchment areas is affecting the ecological balance of the lake, but only the tip of the iceberg. Since the bacteria normally affect already weakened hosts, the experts are carrying out further tests to determine the primary cause.
But they don’t have to look too far. When over 50,000 flamingos died at the lake between 1993 and 1995, laboratory results blamed these on the presence of heavy metals and traces of DDT and other agricultural chemicals.
The results published in August 2001 in the Lake Nakuru National Park’s Integrated Management Plan document, attributed the deaths to ingestion of heavy metals.
Traces of arsenic, lead, mercury, copper, cadmium, chromium, iron zinc, nickel and selenium were among the heavy metals found in the livers and kidneys.
“Organochlorines in the form of the banned DDT were also detected in the liver, kidneys and brains, while tests for algal toxins revealed that the birds had also ingested toxic algae.
“This toxin is produced by a number of phytoplanktons, some which are starting to emerge in our saline-alkaline Rift Valley lakes as a result of eutrophication.” the report said.
Eutrophication is the excessive enrichment of rivers, lakes, and shallow sea areas, primarily by sewage, nitrates and phosphates from agricultural chemicals.
These encourage the growth of algae and bacteria, which use up the oxygen in the water, making it uninhabitable for fish and other animal life. The dissolved fertilisers cause rapid growth of water plants, especially green algae. As the algae die, aerobic bacteria bring about decay, using up oxygen in the water as they do so.
Anaerobic bacteria take over and convert part of the dead matter into smelly decayed products, an ideal environment for 'pseudomonas aeruginosa'.
Although many recommendations were made to protect the lake’s catchment areas then, Kariuki says, most have not been implemented, hence there is reason to believe the birds are dying from the same causes.
One of the recommendations was the protection of land along rivers that flow into the lake to guard against illegal water abstraction and the various agents of water and soil degradation.
Kariuki said that the KWS, which manages the Lake Nakuru National Park, had no control of the activities that took place in the Lake’s water catchment areas.
The Nakuru Municipality, which borders the Park, has a solid waste dumping site problem and has been looking for a new one in the ranches in the neighbourhood.
The current dumpsite is located in an old fault line on the slopes of the Menengai Hill, and it is feared that pollutants from it could be finding their way into the park through floodwaters.
A sewerage plant near Kivumbini Estate was said to be overloaded and therefore incapable of releasing totally safe effluence into the lake.
In the past, heavy metals were said to have found their way into the lake because owners of factories did not carry out the necessary treatment before releasing the effluent to the council’s sewerage plant situated in the western side of the town.
When the then Japanese ambassador to Kenya Dr Shinsuke Horiuchi handed over the Nakuru Sewage Works Rehabilitation and Expansion Project to the Kenya government in 1997, he warned that the project’s desired effects would not be achieved if industrialists did not manage their effluence at the source.
“This is a city sewerage plant not a plant designed to clean industrial waste at its source. Unless the community controls the polluted effluence at the source as decided by the Trade Effluent by-laws, no sewerage plant could guarantee to maintain the clean water in the lake,” the ambassador said.
Kariuki also said that low water flow from rivers into the lake leading to a high concentration of pollutants from the sewerage treatment works could be another source of the problem.
The increased pollution at the lake was also attributed to the collapse of the storm water retention pond at Kaloleni Estate over a decade ago, which led to rainwater from Nakuru Town and its environs being swept directly into it. A source at the council said the pond was currently under rehabilitation. This will facilitate the removal of silt before the floodwater is discharged into the lake. In the Rift Valley, flamingos fly all the way to Lake Turkana and parts of Ethiopia.
Major flamingo feeding lakes in Eastern Africa include Nakuru, Bogoria, Elementaita, Magadi, Turkana and Ol Tukai dam in the Amboseli National Park.
During some seasons, small flocks are found at the small Lake Solai in Nakuru District but their stay is frustrated by the large number of cattle, sheep and goats that graze on the shores.
In Tanzania, the feeding sites include Lakes Manyara, Natron, Embakai Crater, Ngorongoro, Burungi, Eyasi, Balangida and Ndutu, while sizeable numbers settle at Katwe in Uganda. In Ethiopia, the flamingos feed at Lake Abijata, Akaki, and Shalla.
A flamingo census carried out in 1994 and 1995 recorded 2.4 million birds in Tanzania, 1.9 million in Kenya and 223,000 in Ethiopia. Uganda, Namibia and South Africa had about 20,000 each, while Senegal had 12,000.
Flamingoes at Lake Nakuru and Bogoria migrate to Tanzania where they lay and hatch their eggs. They fly back into the country after the fledglings are strong enough to take the long flight to their new home.
It has been observed that no deaths of scavenger birds such as cormorants and others that are on top of the food chain occur when the flamingo mass die-offs occur.
Conservationists have yet to establish the source of the various heavy metals that find their way into Lake Nakuru, but the source of the organochlorines is definitely the farmlands in the catchment areas where fertilisers, herbicides and acaricides are used throughout the year.
Several rivers including Njoro, Larmudiac and Makalia rise in the Mau Forest and discharge their flow into the lake after meandering through the fertile farming areas of Njoro.
Several factories in Nakuru (whose names were not released to us) have received warning letters after they were found to be discharging effluence into the sewerage system.
“In case of fraud, we write to the management of such companies to stop such acts, failure to which we take legal action. But quite a number of the factories have improved greatly,” said an official.
