Symmetry, change, perturbation, and observing mode in natural communities

Abstract

Like a kaleidoscope, nature presents continuously fleeting images of natural communities. It has been difficult to discern patterns of community structure in these elusive images. For both theoretical and applied considerations, however, holistic ecosystem properties need to be identified and quantified. An analogy of a kaleidoscope is used here to describe symmetry, change, and perturbation in the plankton community of Delaware Bay. Loop analysis was used to model the Delaware Bay plankton community at 12 dates in an annual cycle. Loop diagrams consist of qualitative network models based on positive, negative, or zero interactions between variables in a pair for all pairs of variables. The fit of models to the data using the directed change technique resulted in 95% agreement. The core structure contained 18 variables in a three-tiered configuration with distinct subsystems of predators and small-sized algae and their associated herbivores.