In this paper, we present results from studies on marine Vibrio species, in which complex adaptive responses have been investigated. The results of two-dimensional polyacrylamide gel electrophoresis serve to illustrate the usefulness of a global approach, and how it can be combined with other methodologies in order to achieve an improved understanding of the means by which bacteria adapt to alterations in environmental conditions. The overall strategies described in this paper are particularly useful for studies of bacteria for which efficient genetic tools, background genotypes and in depth physiological data are not yet available.