Report 18 -- Scales

## Time and Space Scales

The range of processes and components in oceanic ecosystems is daunting, and new observing techniques are constantly revealing new complexity. Even simple ideas of heterotrophs and autotrophs cannot be distinguished unambiguously in many cases as species cross these boundaries. The functional complexity of the ecosystem is further confounded by the broad range of temporal and spatial scales associated with these processes (Denman and Powell, 1984; Mackas et al., 1985). Because of the nonlinear interactions that dominate ecosystems, one cannot simply ignore processes at scales smaller than the scales of interest (Denman and Powell, 1984). For example, the characteristic scales of variability in the environment may drive the response scales of phytoplankton physiology over evolutionary time scales (Harris, 1986; Abbott, 1993).

The observed richness and complexity of the natural world results in a tension between modelers who try to retain only the critical elements of the system in order to develop a manageable and understandable model and observationalists who insist that such sparse models are missing essential processes. The tension between model robustness and model richness will never be resolved, and the balance point between these two forces will depend on the goals of the model.