The distribution of relict crustaceans in Finland: new observations and some problems and ideas concerning relicts

• Published in: Annales Zoologici Fennici. 1990 Vol. 27; no. 3; pp. 221 - 225
• Main Authors: Särkkä, Jukka, Meriläinen, Jarmo J., Hynynen, Juhani
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Finnish Zoological Publishing Board, formed by the Finnish Academy of Sciences, Societas Scientiarum Fennica, Societas Biologica Fennica Vanamo and Societas pro Fauna et Flora Fennica 01-01-1990
• Subjects: Altitude; Animals; Crustaceans; Cyclopes; Environmental pollution; Fauna; Freshwater; Glacial lakes; Humans; Lake water; Lakes; Malacostraca; Finland
• ISSN: 0003-455X; 1797-2450

The article summarizes observations of relict malacostracan species made mainly in the lake region of Finland. In addition to geographical location, maximum depth, lake area and altitude, human activity also has an effect on the occurrence of given species. Pontoporeia affinis seems to be the most sensitive to human interference, and this and Pallasea quadrispinosa, which is not as sensitive, have returned to areas in Lake Päijänne that were earlier more polluted. Mysis relicta has the widest environmental amplitude in different lakes, while Gammaracanthus lacustris occurs only in largest, deepest and cleanest lakes. Pallasea should be included in the fauna of the Baltic. The question is raised of whether the concept of relict species should be broadened to include also some other cold-stenotherm species, in particular certain calanoids, harpacticoids and rotifers, and also meiobenthic species. It seems that at least Pallasea might be able to immigrate to areas situated higher up. The reason for the absence of Saduria entomon in the large lakes of Finland has not been ascertained, and the advantages and disadvantages attached to transferring it and comparable relict or other species are not generally known in sufficient detail.