It is an ecosystem with many names. It has been called “Darwin’s dreampond” because it holds a population of the tropical cichlids fish that has shown immense signs of evolution and adaptation over the past 12,000 years. Some may call it, “the ultimate biology project.” It, unfortunately, has even been called “the sick giant” as of late, because of the increasing number of pollutants and other factors that threaten its well-being. Central Africa’s Lake Victoria has a huge impact on the region in which its located. The countries surrounding the lake depend on it for commerce, food, and clean drinking water. This paper will discuss the biological issues facing Lake Victoria. These issues include what role evolution has played on the Cichlidae family of fish, what factors are contributing to the declining health of the lake, how those factors are affecting the inhabitants of the lake, and what steps are being taken to ensure that pollution and Lake Victoria rests between the countries of Uganda, Kenya, and Tanzania. It was first found by the British Explorer John Speke in 1858. Lake Victoria is the world’s largest tropical lake, and second largest freshwater lake, behind Lake Superior. The lake’s size is comparable to the island of Ireland, covering 69,000 square kilometers. It lies in the rift valley system, which is a 3,500 mile stretch of cracks that run deep in the earth’s crust that begins at the Red Sea and stretches south to Mozambique, but the lake itself is not actually part of this system (www.jambokenya.com).
In its present state, Lake Victoria stretches nearly 69,000 square kilometers, and at its deepest point, is 69 meters. This is a relatively shallow lake for the amount of area that it covers. In contrast, Lake Superior. Recent studies have given evidence that the lake was 65 meters deeper at some point in time between 15,000 and 17,000 years ago (Coleman, 1999). These studies have led some scientist lot hypothesize that Lake Victoria, at some point in time, was actually lower. Some have also concluded that most of the area that is the Lake today was dry land, but not all of it. That is the one key behind the evolution of cichlids in this lake. The massive lake that existed approximately 15,000 years ago did not disappear entirely. Many small “ponds” derived from the shrinking of the lake. When the lake shrunk, some of the vegetation and animal life were diverted throughout these different, smaller lakes. Different lakes would have different types of vegetation and animals, for These life forms, no matter how complex, would essentially be forced to the ponds that formed near where they “hung out” in the big lake. One of the most “spread out” species in the big lake were the cichlids. Thus, cichlids could be found in many of the ponds.These ponds were obviously contained much less space than did the big lake, allowing for less characteristics as far as types of terrain, number of different types of organisms (which includes both predators and prey for the cichlids), and amount of space.
This decrease in the number of variables that the cichlids had to deal with allowed the fish to specialize and conform with the needs of the particular pond. Konings says that an important difference is to make is between “speciation,” which is the actual changing and morphing of one species to form an entirely different species and “evolution,” the gradual change of genetic material (DNA) over an period of time. The cichlids of Lake Victoria today vary greatly in size, color, diet, preffered living habitat, parenting methods, breeding habits, and other characteristics. All these changes come about despite the fact that the amount of time in which cichlids experienced these changes is considered an evolutionary brief period of time by most scientists. As amazing as the changes to the Lake Victorian cichlid are, evidence of this fish’s ability to evolve is testified in other parts of the world, as well. Most cichlids of Lake Victoria have managed to stay more with the “torpedo-style” of body. It is not uncommon for cichlids in South America to have evolved into a more plate-like form, allowing them to live and feed in the isolated rivers and lakes of the rainforest (Musselwhite). In 14,000 years, 400 species of cichlids had Now the cichlids, as well as all the life that benefits from a healthy Lake Victoria, are faced with an astrnomical problem. The 400 species that once were have dwindled down to 200. This is due to a couple factors. First, the introduction of the Nile perch. This massive fish that can grow to be six-foot and 200-pounds and survives by feeding on smaller fish. The Nile perch has contributed to the decrease in numbers. Ever since Speke’s “discovery” in 1858, men have been responsible for the explotation of the resources the lake has to offer. Right from the get-go, colonialists began tearing down the forests surrounding the lake, draining swamps, and planting crops that farmers were able to finacially benefit from. Over the course of a few years, these farms grew to plantations. Plantations attracted workers. Workers attracted businesses other forms of business. One of these types of businesses was, as one might expect, fishing. By 1950, many fish populations had depleted so much that they had become commercially extint (Chege, 1995).The most recent, and most threatening, menace to the lake comes in the form of water hyacinth. This plant, a type of free-floating seaweed, has emerged in areas of the lake in all three countries. It forms a thick layer on top of the lake, which does not allow sunlight to reach organism beneath it. It also uses a lot of oxygen, which is already a rare resource the ecosystem. International travel between the three countries via the lake is almost impossible at this point because the plants tangle with the small fishing boats, which the poor countries rely on for transportation, and trap them. Though no one is sure when the plant first entered the lake (1989 was when it was first noticed), many believe that it entered by means of the Kagera River. The weed is growing at an alarming rate. Satelitle photos from 1996 show that the weed consumed nearly 1% of the lake’s surface. Scientist predict that number to be as high as three percent today (CITATION NEEDED). Scientists have offered the solution of harvesting the plant and using it for compost for the nearby farms. One company, Aquarius Systems, is actually in the process of engineering a machine called a “swamp devil.” These machines consist of a 234-horsepower engine that spins two blades, measuring 2.4 meters a piece in diameter. These blades are known to easily handle trees 15 inches in diameter. The swamp devils essentially chop up the vegetation, which is picked up by another device consisting of a conveyer belt and what amounts to a flatbed on a boat. This seems to be a rather effiecent way to clear the vegetaion, and is being warmly accpeted by most lakeside Lake Victoria is very unique ecosystem, both because of its cichlids fish that have shown immense signs of evolution over a rather short period of time, and the fact that it is depended upon by a large number of people for food, water, business, and other functions that are essential to maintain a acceptable standard of living. Since western civilations “discovered” the lake, the resources the lake’s life, as well as humans, depend on and have seemingly taken for grantend have been in grave danger, and continue to decline in If the steps are not taken quickly, chances are Lake Victoria will become a useless cesspool that is nothing but a nusance and a reminder of the wasteful creatures that we are. Fortunatly, though, we have recogonized the problem, and the neccesary governments seem to be willing to work in conjunction with companies like Aquarius Systems in order to providte the lake with the attention and help it requires.
Bibliography:
