Today I must concentrate on just one of the many possible aspects of plankton research, one that 1 believe has a real future given the opportunity and the backing. This is: how the movement and mixing of water masses affect the plankton and, in turn, the effect this has on the other dependent communities and so on the fish themselves. We know that the mixing of different water masses produces conditions that are usually more productive than in either, and this can happen on a large scale, as in the convergences, or on a small scale in quite local areas. Sometimes the cause of the greater productivity is obvious—for example, off the coast of Peru where off-shore winds tend to drive away the depleted surface waters. These are replaced by the upwelling of nutrient-rich waters from below; some mixing takes place seeding the rich water with phytoplankton and resulting in one of the richest areas of production in the oceans and incidentally leading to an export of cheap fish meal that is having repercussions in the European markets.