CLOSING ADDRESS: PERSPECTIVES ON BASIC AND APPLIED, FRESHWATER AND MARINE PELAGIC RESEARCH

When asked to make some concluding comments about this symposium, I did not hesitate long, because I have had the privilege of following more or less closely the development of the various Pelag projects during the years. In fact, I have seen the Pelag in its germ line phase, when I was still working myself at Tvärminne Zoological Station in the early 1980s. We then constructed the first-ever carbon budget for the pelagic and benthic system off Tvärminne, which was submitted to the ICES ecosystem symposium in Kiel in 1982. The pelagic system structure of our carbon flow model was admittedly crude compared with the present knowledge, but, nevertheless, the paper was accepted as a lecture, and we got it published (Kuparinen et al., 1984). Many things have changed since those days, but I have been happy to notice that the good humour and untiring scientific curiosity of the group have persisted through the years. The present symposium was organized by the Pelag group to mark the completion of their third project, and it is no wonder that the selection of symposium topics mirrors the interests of the organizers. As a consequence, during this week we became familiar with different kinds of material fluxes, often vertical (e.g. Wassmann, 1998), but what we especially experienced was an extensive horizontal flux of information, the source of which could partly be traced to long-distance transport, although part of the flux was clearly of local origin. I think that the general structure of the symposium was successful. We have heard nine excellent summary papers setting out the state-of-the-art in several subtopics under the general title of the symposium. In addition, there were many high-quality contributed papers and posters with really impressive data. I am not going to review the whole symposium – to summarize almost fifty papers and a similar number of posters is simply impossible in a few lines. Instead, I shall pick up some thoughts that came to my mind while I was listening the presentations during the week. The symposium had a wide geographical coverage from the Sargasso Sea in the west to the Black Sea in the east, and from the Norwegian fjords and the Baltic Sea in the north to the warm Mediterranean in the south. The salt content of study waters also varied considerably, from the very soft brown freshwaters of the Lammi area in southern Finland to the higher than ocean salinities of the Mediterranean Sea. It was refreshing to see marine biologists and freshwater scientists in the same symposium. The presentations here amply confirmed that the planktonic systems have very similar structure and function throughout the whole salinity gradient. The variations that occur have little to do with salinity as such. Instead, the major differences between fully marine and lacustrine systems probably arise from the different amount and distribution of physical energy (Nixon, 1988b); in addition, the largest space and time scales are only present in the oceans. Yet in the past marine ecology and limnology have tended to be quite separate disciplines, marine scientists not reading freshwater papers, and vice versa. During the recent years, there have been a few conscientious attempts at a better unification, e.g. some symposia have been intentionally organized for both groups combined (Nixon, 1988a; Giller et al., 1994). Having myself done re-