Along this continuum, phytoplankton and zooplankton exhibit characteristic features of ecological structure and function that arise as outcomes of systemic behaviour. A full exposition of this organisational scheme into a rational partition of the global ocean was a landmark in many respects. In essence, this ecological geography addresses the fundamental issues of pelagic ecology and biogeography, which distill to whether, at some level of probability, a deduction may be made about the characteristic features of any region. Here, the definition of region is crucial since it determines the scale of the biological seascape. By placing the typology of seasonal plankton cycles into the context of regional oceanography, characteristic features of ecology can be discerned at two hierarchical scales. The higher level comprises a small number of large compartments (biomes), and the lower level comprises a large number of smaller compartments (provinces), each designated with a unique four-letter code. An initial proof-of-concept for the Ecological Geography of the Sea was demonstrated by estimating global primary production using satellite radiometer data partitioned into biogeochemical domains and provinces. This influential work was published in 1995 with co-authors Shubha Sathyendranath, Trevor Platt, and Carla Caverhill, and stands as the most highly cited paper in the Journal of Plankton Research. Parenthetically, the first paper in the first issue of the first volume of this journal which appeared in 1979 was also authored by Longhurst. The first edition of the Ecological Geography of the Sea (1998) dealt only with the planktonic ecosystem. It was reviewed in "Nature", "Science", "Limnology and Oceanography", and "Trends in Ecology and Evolution", amongst others. The second edition (2007) included considerations of the strong coupling between benthic and pelagic processes that occurs over continental shelves, and between plankton and larger pelagic organisms.