Coupling between physical and biological scales

Temporal changes in population abundance display a great diversity of patterns. This diversity is acknowledged by reviewers of marine and terrestrial data, but their explanations tend to fall into two categories: internal factors related to population or com m unity structure; and external aspects determined by the environment. T he former we associate with terrestrial studies and the latter with marine. In this paper we shall stress the importance of the characteristic timescales in the dynamics of the populations and their relation to the scales of relevant environmental forces. We shall suggest that the coupling between these different scales, rather than the nature of the internal or external processes themselves, can provide a partial description, if not an explanation, of the diversity of patterns.