How light and nutrients affect life in a closed bottle

Kooijman, S.A.L.M. and Nisbet, R.M. 2000. How light and nutrients affect life in a closed bottle. In: Jørgensen, S.E. Thermodynamics and ecological modelling. CRC Publ., Boca Raton, FL, USA, pp 19 - 60.


We evaluate the mass and energy turnover in a canonical community that lives in a closed bot- tle at steady state. We use daphnids, algae and bacteria, called the DAB-community, as example of a canonical community consisting of consumers, producers and decomposers. We built up the system in four steps, starting from the Monod model for the three biota, and include reserves, maintenance and population structure for the daphnids, where the individuals follow the rules as speci ed by the Dynamic Energy Budget theory. This theory provides the theoretical foundation for the widely applied method of indirect calorimetry, that relates dissipating heat linearly to carbon dioxide production, oxygen consumption and ammonia production.

Our evaluation illustrates the application of thermodynamical principles in a very simple, spatially homogeneous, but non-degenerated community. In the full system, we follow the fate of 16 compounds partaking in 16 chemical transformations. Dissipating heat turns out to be a useful measure for the rate of living, which increases almost proportional to light intensity when e ects of temperature are excluded. We also nd that dissipating heat increases for decreasing total nitrogen. We derive explicit expressions for nutrient and biomass turnover and show their relation with dissipating heat, and community structure.

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