This is the third book I have written on the subject of phytoplankton ecology. When I finished the first, The Ecology of Freshwater Phytoplankton (Reynolds, 1984a), I vowed that it would also be my last. I felt better about it once it was published but, as I recognised that science was moving on, I became increasingly frustrated about the growing datedness of its information. When an opportunity was presented to me, in the form of the 1994 Ecology Institute Prize, to write my second book on the ecology of plankton, Vegetation Processes in the Pelagic (Reynolds, 1997a), I was able to draw on the enormous strides that were being made towards understanding the part played by the biochemistry, physiology and population dynamics of plankton in the overall functioning of the great aquatic ecosystems. Any feeling of satisfaction that that exercise brought to me has also been overtaken by events of the last decade, which have seen new tools deployed to the greater amplification of knowledge and new facts uncovered to be threaded into the web of understanding of how the world works.

Of course, this is the way of science. There is no scientific text that can be closed with a sigh, ‘So that's it, then’. There are always more questions. I actually have rather more now than I had at the same stage of finishing the 1984 volume.