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Page 1 of 10 The Critical Role of the Mekong and Tonle Sap Corridor for Tonle Sap Lake ecology and the important Role of the Waterway Wetland in Cambodia by Touch Seang Tana 1. Introduction For almost 20 years involving in the fisheries sector, especially the inland fisheries, a thousand doubts rise up in my mind at every step of approach on how the nature cerates this critical inland water system and its tremendous resources. Why the Tonle Sap Lake reputed as a larges fisheries productive freshwater systems for many millennia (Chu Ta Kwan, 1329, Mohout, 1857-9, Vincent, 1860-1, Petiole, 1911). What this lake was before the above period as Rainboth, 1996 quoted in his Zoogeography book that the freshwater Tonle Sap Lake aged about five thousand years and the present Mekong and Tonle Sap River were only two thousand years age. A French researcher, August Pavie,1898 was well explained in his Researcher sur L'Histoire du Camboge, du Laos et du Siam, indicated that the whole central plain of Cambodia was a marine bay and the Mekong River reached this bay at somewhere near the entrance of the present Tonle Sap Lake (see Figure1). This latter information was well explored by geological and archeological works on textile soils and fossiles located 12 meters beneath in Samrong Sen (northeastern Kampong Chhnang town), which represented the prehistoric human settlement of this region. Before the lake connected to the Mekong and Tonle Sap Rivers, neither data nor information proving the biological richness of the Tonle Sap Lake were available. Therefore, these remain doubtful until to day but Rainboth (1996) has poited out that divesification of the biological richness of the Tonle Sap Lake occurred during time that this lake was connected to the Mekong River by the Tonle Sap corridor and the importance role of the reverse water system between the Tonle Sap Lake and Mekong river. In addition, Carbonel and Guiscafre, 1963 dicovered the importnce role of the watershed of the Tonle Sap Lake, which has also contributed almost a half of the flood regime to the lake during rainy season. Thus not only the Mekong water but also the surrounding tributaries had played the importance role to flood the Tonle Sap Lake. These above argument are of great contribution to my pragmatic preference for understanding the important role of this ecosystem by setting up a scientific method through an evolutionary approach to investigate this complex system. Hermeneutic is the salient point this attempt to grasp a scientific knowledge, which based on objective historical understanding. However, the history of the nature was less interested by historian in the past as political events were predominant. Even though, a critical uniqueness representing by edible aquatic animal for people livelihood was also attracted some hobbyist writer, through which we can understand some of our natural evolution. The economic interest has turned this splendid natural ecosystem to heavy commercial exportations, which are consequence of the depletion of the utilized resources. The evolutionary change of our nature are the effect of three logical factors: the nature-nature contradicted phenomena (1), the human nature contradicted phenomena (2) and the human-human contradicted phenomena (3). The latter factor is complicated and difficult to understand as it is the effect of the two groups of people who have same or different interest on the nature. However, the environmental uniqueness and biological richness of the Tonle Sap Lake in accordance to the integration of the Mekong and Tonle Sap Rivers phenomena and its gradual change has become a critical subjects of the politician, academician, administrators, economist, biologist, environmentalist, naturalist etc. at the present time. A serial number of publication of the foreign academician and scientists in the past and in recent period shown that the richness of fish and other animal population had no longer satisfied the economic ambitiousness of the commercial corporation and administration and especially socio-economic of local people. Management and law enforcement cannot stop this rampant situation of destructiveness due to lack of understanding of the critical problem of the commonsense of knowledge on this ecosystem. Some scientists and academician are dogmatic with inductive research for management improvement but inductive finding is far behind the critical reality of the situation. A priori of induction in scientific research is become a subject for discussion between the finding and the reality in the Cambodian inland fisheries ecosystem for convincing the manager to alleviate this environment from threat of serious deterioration. The inductive research is finally failed to prove the truth that can be used as a powerful argument to influence the decision maker. However, we already knew that some of the most important animals have disappeared or under threat of Page 2 of 10 extinction, and that past abundance is far from ensuring future success. This is the fact, and clearly, although we could do something about is, we cannot do much. Darwin's theory of the origin of the Species and the Natural Selection is quiet clear that past biodiversity abundance never ensures future biodiversity success. According to this theory, animals which are not well adapted to their changing environment perish, consequently those which survive (up to a certain moment) must well adapted. This is not the nature of an empirical theory, but is a logical truism (Popper, 1972, P.69). To search for truth in the critical problem of the biodiversity evolution of the Tonle Sap Lake with exploitation for human benefit is my pragmatic preference in scientific discovery since this environment has changed but not too fast for long period of times, and not too radical, otherwise all life in this ecosystem and all adaptation will come to an end. In the possible way of existence, all living organism in this world are slowly adapted or sensitive to the environmental changes and changing conditions, there is therefore no reestablished harmony between the properties of the organism and those of the changing environment. Only if the organism produce mutations, some of which are adjustments to impending changes, and thus involve mutability and if the process of adjustment has gone on long enough, then the speed, fitness, and complexity of the adjustment may strike us as miraculous (Popper, 1972, p 70). We are now at that now at that stage where biological existence resists under human strike of exploitation in the Tonle Sap Lake environment. This paper described the physical, ecological and biological survival of the complexity of adjustment of the Tonle Sap Lake environment mutation according to the important waterways corridor evolving under serious human and nature pressure. 2. Logic of important ecosystem in the Tonle Sap Lake and the role of the waterway corridor for biological mutability The Tonle Sap Lake or Great Lake in Cambodia is one of the most well-known water body covering on a very large area (2,700-3,00sqkm) during peak dry season in May and expanding 5 time bigger (15,00-16,00sqkm) during the peak flood period in late October. The Tonle Sap Lake received the flood regime from the Mekong Rivers through the Tonle Sap River between the period of June and September and on the other hand, from the surrounding stream of the northern and weather watershed (Stung Chinit, Stung Sen, Stung Storng, Stung Kampong Khleang, Stung Siem Reap, Stung Kralanh, Stung Monkul Borey, Stung Pursat, Stung Krakor and Stung Boribo streams) The longest and largest streams in terms of discharge water into the lake are: Stung Sen, Stung Storng and stung Sangke, which following by Stung Chinit, Stung Pursat and stung Boribo (Carbonel and Guiscafre, 1963). The physical and ecological importance of these flood supplier sources to the Tonle Sap Lake is the creation of the complex delta system consisting of a number of waterways and a huge flooding gallery forest. The Mekong source of flood supplier has created a huge delta from Snoc Tru, Kampong Chhnang down to Peam Long Vek, Kandal Province at the last part of the Tonle Sap River. Stung Sen stream created a delta at Phat Sanday, Kampong Thom province. Stung stram created a delta at Tonle Chmar and Stung Sangke sream with the combination of Stung Kralang and Stung Monkol Borey streams created a second largest delta after the first delta in Kampong Chhnang province. The importance of the delta ecosystem are its flooding gallery forest and numerous waterways that are not dried up during dry season, which provide alterative choice for different species mutation. Most fisheries scientists, ecologists and environmentalists consider flooding forests as a great habitat for fish and other aquatic animals in terms of feeding grounds, spawning grounds and safe shelter. But my pragmatic preference in scientific observation consider this as only part of logical truism, it is not a clear empirical finding of an environment. Because the mutability of any aquatic environment occurred according to space and time the interaction of the surrounding climate, which may effect the biochemical properties of that environment. In reality, the water quality in such environment changes at least three to four times during the flooding period of four month due to the biochemical mutation. In accordance to biological theory some aquatic animals (reptiles or amphibians and a little air breather species) can resist in acidic or nitrogen water with its fast adaptation but some other (mainly fish species) are not, so these latter used to evacuate themselves to the better place for survival. The only one choice of evacuation of these latter animals is the waterways that they used to displace to other habitat for saving lives. This means that not all ecosystems or habitats its change its environmental properties at the same time and same level because the property composition is different from one to another habitat.

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