The Changes of Ecosystem Goal Functions in Stressed Aquatic Communities

Abstract

The changes of biomass, exergy and structural exergy under the action of various chemical pollution (addition of nutrient compounds, pesticides, chlorinated phenols, oil, heavy metal ions, acidification etc.) are analysed for 50 experimental works with model aquatic ecosystems -microcosms, mesocosms and experimental ponds.<br>Structural exergy is shown to remain at constant level or to increase when the allochtonous compounds can be metabolised by ecosystem, or when the ecosystem can adapt itself to the input of toxicant by structural changes. When the substance is too conservative, too toxic or/and is coming in too high concentrations, structural exergy is decreasing, demonstrating the inability of ecosystem to adapt to this influence and irreversibility of changes in ecosystem.<br>The possibility to use such parameter as structural exergy for estimation of ecosystem state and its changes under various external influences is demonstrated. It reflects the state of ecosystem and can indicate the degree of ecosystem adaptation, decreasing when important for ecosystem functioning components are eliminated.<br>In experiments with mathematical model of lake Baikal ecosystem exergy content is shown to increase after addition of nutrients and to decrease after addition of phenolic compounds, reflecting the general shifts in ecosystem.;The changes of biomass, exergy and structural exergy under the action of various chemical pollution (addition of nutrient compounds, pesticides, chlorinated phenols, oil, heavy metal ions, acidification etc.) are analysed for 50 experimental works with model aquatic ecosystems -microcosms, mesocosms and experimental ponds.<br>Structural exergy is shown to remain at constant level or to increase when the allochtonous compounds can be metabolised by ecosystem, or when the ecosystem can adapt itself to the input of toxicant by structural changes. When the substance is too conservative, too toxic or/and is coming in too high concentrations, structural exergy is decreasing, demonstrating the inability of ecosystem to adapt to this influence and irreversibility of changes in ecosystem.<br>The possibility to use such parameter as structural exergy for estimation of ecosystem state and its changes under various external influences is demonstrated. It reflects the state of ecosystem and can indicate the degree of ecosystem adaptation, decreasing when important for ecosystem functioning components are eliminated.<br>In experiments with mathematical model of lake Baikal ecosystem exergy content is shown to increase after addition of nutrients and to decrease after addition of phenolic compounds, reflecting the general shifts in ecosystem.