Marisia - Maros Megyei Múzeum Évkönyve 32/1. (2012)
Zoology
Aquascaping as advanced environmental enrichment tool Fig. 12: The nitrite level dynamic during the experiments (ppm) The importance of oxygen and oxidation-reduction potential. The oxygen has undoubtedly an important function in aquatic ecosystem and there is a strong relationship between the oxygen producers and the consumers, past including animals, microorganisms and plants not least during the dark phase of their metabolism. The dissolved oxygen demands of aquatic organisms and the respiration intensity increase with water temperature and water saturation in dissolved oxygen (DO) also depends on temperature. The figures below show the dynamics of water dissolved oxygen content and oxygen saturation during the experiments. The results are in concordance with the mechanisms from natural densely planted aquatic environment from tropical and subtropical areas where DO content records values between 4-14 ppm with frequently exceeding of saturation point. A water saturation level between 70 - 130% represents an optimum range. Fig. 13: Diurnal variation of water DO content (ppm) Fig. 14: Diurnal variation of water DO saturation (%) As the DO consumers and biological processes DO consuming increase due to biological reactions, the DO water content during morning significantly decreases and increases during evening as result of plants photosynthesis. There are controversial opinions regarding the optimum DO content for plants growing. Krausse and others (1990) quoted by Kasselmann (2003) refers to negative impact of high DO content (bigger as 4-5 ppm) on nutrients level from water and plants growing rate; he sustains this opinion by frequently depletion of DO content below 3.5-5.5ppm from tropical 127 Fig. 11: The ammonium level dynamic during the experiments (ppm)
