When the Europeans came to the great African Lake they named after the British Queen it was a like a sea in the middle of the land. I have myself been in the steamer and looked around the boat to see no land in any direction.

This sea is not all that old. Its huge variety of cichlid fish species is said to have evolved in a mere 14,000 years - a blink of the eye in evolutionary time. This great Lake formed in a fold in the earth related to the rift valleys on either side - which one day may tear this part of Africa free, like Madagascar broke off, long ago.

It is not in the same condition as when it was discovered. European sports fisherman liked the idea of fishing there for Nile perch - which had never managed to jump the various waterfalls and cataracts to get into the lake. They were assisted to make that final jump. Soon they had eaten most of the indigenous species of cichlids and tilapia that supported villages of fishermen all round the lake. Some fishermen did learn to catch the new fish, but to process its oily flesh needs more firewood. Thus the introduction of this new predatory species increased the rate of deforestation.

The next introduction of an alien species has been much more harmful. It is the Water Hyacinth whose origin is in South America. It has now spread to all the tropical continents where, without effective predators, it swiftly covers all lakes and rivers, making fishing and hydroelectricity difficult or impossible. In Lake Victoria it clogs the ferry terminals in Uganda, Tanzania and Kenya. It blocks the inputs of the Owen Falls Dam which generates electricity for Uganda and Kenya. It provides wonderful habitats for snakes and bilharzia snails.

Alien species are not the only things introduced to the water. Victoria may never have impressed for the purity of its water like Baikal but the sewage pouring in from such towns as Homa Bay in Kenya has not helped. Even before the hyacinth arrived I have stood on a hill in Homa Bay and observed a great brown stain spoiling the waters and spreading into the open water - which tens of thousands of people use for drinking. The hyacinth has used these nutrients to spread even faster - indeed to some extent this is a positive development. In Florida the weed has been used as a means of purifying sewage, and especially to remove heavy metals. The weed can then be used as a fuel. In the lake however, the dead plants will fall to the bottom, use up the oxygen and turn large areas into swamp after killing the fish.

No doubt it would take centuries to destroy the whole lake as a water storage but Egyptians, reliant for 7000 years at least on a regular supply, should not feel complacent. Nor should Europeans. Changes in the Mediterranean outflow into the Atlantic have been suggested as an influence on the water currents that bring warmth to western Europe. Could hyacinth in Lake Victoria make the winters colder in Europe? One can't rule it out.

 When did it get in? A UN Conference report (2) states:

In the late 1980's the weed completed its colonization of the White Nile watershed by invading the headwaters of the Kagera River in Rwanda, and from there began the colonization of Lake Victoria, the Victoria Nile, Lake Kyoga (though this may have become independently infested in the late 1980's) and Lake George. Distribution of water hyacinth as an ornamental was once more, a likely cause of its spread in East Africa.

It has been suggested that a Belgian businessman in Rwanda was growing the weed to sell to Europe. When he had to leave his stock was thrown into the river. Perhaps this is a modern myth.

The same report states:

In 1995 the weed arrived in the Kwanza River in Angola and in Lakes Tanganyika (J Disney NRI pers. comm.), Malawi and Kariba (Zimbabwe), having now colonized all of the major rivers and freshwater lakes (with the possible exception of Lake Tana and the Okavanga) in Africa.

 Is this situation entirely gloomy? There are possibilities. One is to look for natural predators - though the situation up to now is not very promising. Another is to use the hyacinth as a resource. In fact attempts to harvest the weed are not likely to succeed unless it can be used for something. One possibility is to see the weed as a solar energy collector and use it as a source of energy. There is so much of it that all the countries concerned: Kenya, Tanzania and Uganda, could achieve some of their Global Climate adjustments by using biogas from the weed instead of oil products. The biogas could also replace some use of charcoal and firewood, thus relieving the pressure on forests. Once gas has been made there would be a large supply of compost to sell to farmers to improve their soil. Indeed, if this process could be integrated, coffee farmers might be able to upgrade their output to Organic standard and receive the higher price paid for this higher quality product, for which there is a growing market.

The old way of life of fishing villages has vanished, perhaps for ever. To replace it there might be a new industry of harvesting the weed and processing it for the benefit of other industries.

But as Burke and Ornstein say in the Axemaker's Gift, we need to start thinking in a more comprehensive way than has been necessary since humanity began its technological development with the stone axe. Everything affects everything else.