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MOSCOW, October 6. /TASS/. Scientists from the Siberian Federal University (SFU) in collaboration with their German colleagues have concluded that dead zooplankton do not accelerate the decay of complex organic matter, the SFU’s press office reported.
This is the first conclusion made during the course of joint research aimed at understanding the way in which hardened vegetable remains and other complex organic compounds undergo the decomposition processes. Such efforts will help us better understand the carbon cycle in nature and might also be useful in studying global warming.
"Very often, water reservoirs accumulate decomposition-resistant organic matter - hardened vegetable remains and humus. The test studies showed that this matter by itself undergoes only very slow decomposition, nevertheless, it disappears somewhere without settling at the bottom. Before, many researchers presumed that the decomposition of organic matter was accelerated by the presence of zooplankton in water which act as a primer, an easy and fast meal for microorganisms which lack the energy to synthesize enzymes for the decomposition of more complex substances. However, our studies so far have not validated this hypothesis on the primer meal," said Olesya Kolamkova the study’s author and SFU engineer-researcher.
During the first stage of experiments, scientists reconstructed four types of water micro-ecosystems. The first group was supplemented by humin (a mixture of degradable-resistant organic substances) and dead zooplankton (microscopic daphnia crustaceans), the second - only by dead daphnia, the third - only by humin substances. For a period of two weeks, the researchers observed the process of complex organic matter decomposing in order to evaluate the effect of the presence of dead zooplankton on the rate of decomposition.
As a result of the experiments, the researchers did not find any pronounced impact on the primer meal. However, some differences in the composition of the bacterial community of microecosystems were revealed. As various types of bacteria specialize in consuming different substances, this finding might assist in revealing conditions in which complex organic matter decomposes. At present, the researchers are in the process of composing a paper on the study’s results and plan to initiate the second part of the experiment where the ecosystems will be supplemented with microscopic fungus, which is known to interact with bacteria and therefore is supposed to play an important role in the whole decomposition process.
If the scientists understand how tonnes of durable matter washed out from different soil to the water reservoirs disappear, the account of carbon dioxide in nature will become more precise which is important not only for aquatic ecology but also for studying climate change. The experimental part of the work is being held at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (Stechlin, Germany) within the framework of the joint research program "Mikhail Lomonosov" supported by the Ministry of Education and Science of Russian Federation and DAAD (the German Academic Exchange Service).