Some basic physics

Abstract

The physical processes of turbulent mixing are clearly of great importance to the ecology of phytoplankton populations (Margalef, 1978b). Physical processes are the basis of many of the perturbations which are so important for ecology of the organisms. In fact Margalef regards the external supply of turbulent energy to the water column as an energy supplement to the community. The spatial and temporal patchiness in the physical environment arises from the interaction of solar heating and wind mixing in all bodies of water from rain puddles to the oceans. As I indicated previously the differences between limnology and oceanography are only those of scale: granted there is salt in the oceanic water which modifies density structures, but the basic processes of the generation and dissipation of turbulent kinetic energy are the same. What is really different about large bodies of water as opposed to small ones is the presence of motions driven by the rotation of the Earth. The balance of solar heating and wind mixing in large bodies, when coupled with rotational effects, results in large scale horizontal water movements which add a whole new dimension to the ecology of organisms in these systems. For a full treatment of physical limnology and oceanography the reader is referred to the more specialized texts: it is my purpose here to provide some basic definitions and to outline some important features of the environment relevant to the organisms.