LAKE TYPOLOGY REVISITED. AN UPDATED VERSION OF AN OLD CONCEPT.

O.A. Sæther¹ and O.A. Schnell². ¹Museum of Zoology, University of Bergen, Bergen, Norway, ²LFI/Department of Zoology, University of Bergen, Bergen, Norway

Sæther (1979) listed common profundal, littoral, and sublittoral chironomid species in temperate Holarctic lakes and delineated 15 characteristic communities, which correlated strongly with the ratios of total phosphorus and chlorophyll a to mean lake depth. This system was then used extensively to study the biological consequences of both eutrophication and acidification. During the last two decades nothing has been done to update the system, although several systematic revisions have appeared, making it possible to improve the usefulness of the concept. Lately, many studies have shown that the temperature regime often is decisive for the composition of chironomid communities. Here we revise, correct, and extend the species lists given by Sæther, mainly in the oligotrophic range. The classical lake typology system is mostly descriptive and empirically based, and in effect sums up a vast amount of research experience from ca. 1920-80. It is potentially as useful today in climate change research on chironomids as it was in the era of descriptive limnology and in eutrophication research. If temperature is regarded as the main fundamental factor structuring chironomid communities, the traditional lake typology concept can play a significant role in understanding climate-induced changes, alongside the more mathematical approach of multivariate statistical analysis.