The maximum power principle: An empirical investigation

The maximum power principle is a potential guide to understanding the patterns and processes of ecosystem development and sustainability. The principle predicts the selective persistence of ecosystem designs that capture a previously untapped energy source. This hypothesis was investigated empirically in controlled and replicated tests conducted in planktonic microcosms. Microecosystems that developed under a pH-controlled light regime, in which light duration was altered based on changes in an ecosystem-controllable variable (water column pH), were compared with those that developed under fixed photoperiods. According to the principle, pH-decreasing (and power-increasing) organization should selectively persist under pH-controlled light. To assess changes in pH dynamics that occurred under the alternative selection regime, in which photoperiods were not linked with pH-affecting selection or organization, the microecosystems that developed under fixed photoperiods were subjected to pH-controlled light on the last day of each test. The daily light duration increased 506 min on average in microecosystems that developed under pH-controlled light and 412 min on average in microecosystems that developed under fixed photoperiods. Selective reinforcement of acid-secreting blue-green algae in response to CO2 and nutrient limitations could account for the greater increase in power acquisition in microecosystems that developed under pH-controlled light.