The Swamps Of The Danube Delta

excerpt After I have outlined the measures taken in order to improve the biological conditions and to capitalize on the potential the Razim lake has in respect to fish production in both salted and fresh water, I find myself obliged to describe briefly the measures taken for improvement in other regions of the Delta. Apart from the already described lagoons, the Danube Delta comprises other three types of lakes: 1. The lakes situated on the shores of the marginal branches, separating the Delta from the main land: by their origin, these lakes correspond to the old estuaries of the tributaries flowing into this sea gulf, which were closed by the marine strips. To this category belong for example the lakes of Ialpug, Catlabug, Kitai, Cogurului, etc., situated on the left shore of the Chilia branch, the Bessarabian side, or the lakes of Crapina, Somowa, Agan, Mahmudia, which are situated on the right shore of the St George (Sf. Gheorghe) branch, on the Dobruja side. 2. The lakes of the Delta, namely those contained between the three branches of the Delta, which represent the descendants of the old marine gulf (the gulf that originally formed the border of the Danube, and which later transformed itself into the Delta) closing up large areas of fresh water that were open or partially covered by a thick layer of floating vegetation. 3. The "zatons", corresponding to parts of the sea, which were transformed into marine gulfs as a result of the continual progression of the Danube's branches towards the sea, and then separated from it by the marine strips. These marine gulfs are enclosed by marine strips built by the sea, and they are transformed into either shores or lagoons when they are supplied with fresh water or in the so-called "zaton," where they are long and narrow and don't have a direct source of water supply. All these formations become united with the shore and they become a part of the water complex of the Delta. As the Delta goes through a continuous evolution, all the lakes belonging to these categories are exposed to all sorts of unfavorable changes, which modify their biological conditions and diminish their productivity. A flow of fresh water which is too strong brings a great quantity of alluvia which fill the lakes; on the contrary, the isolation from the shore of the surface of water no longer allows the lake to have fresh supplies, resulting in oxygen depletion, imperfect decomposition of dead vegetation and the formation of a sapropelic basin on the lake bed, containing asphyxiating gases deadly to the animal life. The isolation of the "zatons" of salted water and of the lagoons has negative effects which I described in my study on the Razim lake. In order to maintain good conditions of productivity in all these waters which cover enormous surfaces I had to draw up a plan of works of hydrobiological amelioration, a plan to which the engineer Vidrascu brought the solutions necessary for its execution. A series of less important works was already done and at the moment two major works are being dealt with: one on the island of St George and the other one on the island of Braila. They are both based on an essential conclusion I reached after much and detailed research: in the part of the Danube that is most often flooded, fish production is proportionate to the flooded surface. The higher the level of the water and the longer the period of flood, the greater the production; the myriads of germs of the aquatic organisms from the soil of the flooded land, which are latently alive, will form rich nourishment for the fish and their babies; thus, more and more nutritive substances of the soil as well as those brought by the flooding waters will be capitalized on as food for animals and vegetation. In accordance with these conclusions, we have drawn up the projects for the island of St George, where we are going to maximize the potential of about 120,000 ha, which, until now, used to produce only 8 kilos of fish per hectare. A big channel for the supply of the whole island, with ramifications for all the lakes and swamps, and dams and canal locks that are meant to keep the level of the water up for as long as possible, are being built and will have been finished by the end of this year. On the island of Braila, the upstream deepening of the channels of supply and the dam, with canal locks of the main channels, will have the same results, by increasing the surface to be flooded and by maintaining the flood as long as possible for the fish to have the time to feed on the rich food which will help them grow. An entire series of similar works are envisaged or have already been started. from Les marais du Delta, in Rapports et Procès-verbaux des réunions de la Commission Internationale pour l'Exploration Scientifique de la Mer Méditerranée, Paris, December 1932
Translated from French

by Grigore Antipa (1867-1944)