Modeling Chaos: A Long-term Study of a Mesocosm

Source: Beninca et al (2008). Chaos in a long-term experiment with a plankton community. Nature 451:822-825.

Ecological systems are chaotic in nature. Theoretically, this chaos can emerge from competition, predator-prey interactions and food-chain dynamics. Empirical data, however, is scarce mainly due to the inherent complication of disentangling the external variables (e.g. weather) from intrinsic interactions. In this study, the authors study a complex planktonic community for the first time. This community was cultured in a controlled microcosm with constant external conditions for more than eight years. The species in this community (along with the food-web structure) are given in the figure below.


These species were counted twice a week for 2319 days (690 data points). These data points very well capture the correlations originating from competition, predator-prey or even mutualism interactions in the community. These results show that species interactions can create significant fluctuations in the population of each species. In addition, they showed that while in short term the system was predictable, exceeding 15 days significantly decreased predictability. This abrupt decrease is a marker for chaos.

In sum, this small community shows signatures of chaos through fluctuations in the abundance of species.