The Delta was formed as a result of the interaction between the Danube and the Black Sea under certain geographical and geological circumstances. Presently, in front of the mouth we can still watch the process of formation of new Delta parts: the sea currents and the sea waves driven by the winds push the river's alluvial deposits towards the south and slowly deposit them in front of the Delta, isolating parts of the sea, forming the so-called lagoons and lakes. In this phase we can find for example, between Sulina and Chilia, a still developing lagoon, Baia de nord or Musura. South of St. George, right besides the mouth of the arm that bears the same name, the Sahalin island appears. If from a hydrological point of view things are relatively simple, from the point of view of the life of the plants and animals great and complicated changes are happening. And it is only natural to be so because it's there that they belong when one passes from the sea's salted water to the fresh water life of the Delta. Here the environment is constantly changing: when the Danube has got bigger waves, the water turns fresh. Numerous sea organisms that existed here met their death, being unable to resist this change. When powerful winds start blowing from the south-east, the sea water floods these places, dramatically changing the life conditions.(conditions for life). Countless salt-water creatures appear and huge numbers of the ones that came with the Danube's fresh water die. What is the result of this game? The result is that on the bottom of the water huge quantities of corpses decompose and richly nurture the creatures that manage to survive. But who are these lucky survivors? They are the plants and the animals that manage the sudden environmental changes. On deeper water bottoms there are enough microscopic sea weeds, whereas in superficial waters there are certain species of sea plants. In the ground mud there are several species of Chironomidae, and a few varieties of small crawfish. In general, the permanent residents are rather scarce. But whenever these places are invaded by the fresh or by the salted water, because of the food abundance the plankton as well as the bottom inhabitants develop in huge quantities and attract the whole consumers' array. That is when species that don't usually live in the delta show up, such as the mackerel, the shad, the Black Sea sprat, the sardines, the atherine. When the water turns fresh, these species disappear and the ones from the Danube marshes appear. Each one finds plenty of food here. Slowly enough, the battle between the Danube and the Black Sea ends: the fresh water wins, with the help of the sea currents and waves which, through the river alluvial deposits, end up by completely closing these disputed territories. On the sand stripe a dense vegetation settles (especially reed), thus giving birth to a new marsh. Surely, we can't wait until the Musura or St. George Meleana will become marshes. We can find in return parts of the delta that represent all the evolution phases. We must say that along with the separation from the sea waters, therefore along with the marsh as such, even the contradictions that determine the following process become different. The direct action of the sea disappears and what becomes important is the interaction between the hydrological factors (water currents, alluvial deposits, etc.) and the biological ones (the vegetation and the fauna). The Red Marsh (Ghiolul Rosu
) – the youngest one in the entire Delta – represents this moment in the evolution. The great water surface, the deep bottom made of sandy mud create certain life conditions, favorable to specific creatures. Here, on the bottom, certain Chironomidae species live, and among plants, a big sea weed, Chara, which forms huge meadows covering the marsh bottom. Around the marsh, there is a sea of reed which made enormous fields of driftwood. Only there where the bank that once separated the old lagoon gets taller, there are a few willow trees. Here we can also find the Rosulet fishery (cherhana
). If we want to see the seeds of the next evolution of this marsh we must search its margins. Here, under the reed's protection, it gets really quiet; the water isn't disturbed by the winds. The mud brought in by the waters, as well as the cellulosid one resulted from the reed and the rest of the other plants deposit unhindered, raising the bottom and nurturing it with nourishing substances. As there is more light on the higher bottom, different species of vegetation start appearing and further away towards the margins the first floating plants – the white water lilies. Therefore, the open marsh's biocenosis is replaced by another, characteristic to small floodable areas (japsa
). This replacement is a complex and interesting process unfolding slowly. The creatures of the marsh biocenosis themselves, in their interaction with the hydrological and climate factors, change their life conditions, making them improper for themselves and suitable for other creatures.We can say that a biocenosis, through its activity, prepares its own disappearance and replacement by another biocenosis.
Tineretului, 1960 At the age of 92 (he was born on March 13, 1915), Nicolae Botnariuc can boast a career – as both an academic and a scholar – that includes quite a few exceptional achievements. After defending in 1946 his thesis on inferior crustaceans that periodically populate the marshes, he was appointed in 1948 a reader and chair of the Department of General Biology at the Faculty of Biology in Bucharest. In 1961 he published From the History of General Biology
, a massive work of 755 pages that was, however, heavily influenced by the ideology of the time. These misconceptions were abandoned in a new volume, General Biology
(425 pages), that he published in 1979. Between 1970-1971 Nicolae Botnariuc led the first Romanian expedition that crossed the African continent from west to east. A zoologist, ecologist, and militant for the protection of nature, Professor Nicolae Botnariuc had important contributions to the study of the Danube Delta ecosystems (The Primer of Organic Substances in Aquatic Ecosystems
, The Primer of Plankton Production
, The Ecological Role of Macrophyta
, The Ecology of Bivalve Mollusks
). The results he obtained were made known to the scientific world by means of over 60 papers. His profound and detailed knowledge of the Danube Delta enabled him to publish several works that were addressed to the general public. He is also the author of Life in the Delta
, a unique work of science popularization in Romanian literature.
by Nicolae Botnariuc