Harpacticoid and cyclopoid fauna of groundwater and springs in southern Finland

The groundwater fauna, of which scarcely anything has previously been studied in formerly glaciated areas, was richest close to the water table and diminished markedly at greater depths. However, few individuals were generally recorded per 1 m(3) of water. Bryocamptus minutus was the most abundant species of copepod at an esker site, the other species recorded being Attheyella crassa, Bryocamptus pygmaeus, Moraria brevipes and Parastenocaris phyllura, and some species from the genus Diacyclops. At a shore bank infiltration site M. brevipes was the most numerous species. However, one esker site examined did not have any animals. Springs, which were grouped into those in a natural state and those under anthropogenic influence, had some species in common with esker groundwater, but also Paracyclops fimbriatus, Acanthocyclops robustus, Acanthocyclops vernalis, Diacyclops bicuspidatus, Megacyclops viridis, and the harpacticoid species Bryocamptus cuspidatus, Bryocamptus echinatus and Canthocamptus staphylinus. Of the spring copepods, P. fimbriatus appeared to withstand the influence of road de-icing with NaCl, but numbers of Moraria brevipes were reduced under this influence. Bryocamptus echinatus was more numerous in springs having a high oxygen content and high pH. The species found in esker groundwaters and springs were in part the same evidently cold-stenotherm species which inhabit the profundal zone of oligotrophic lakes. (C) 1998 Elsevier Science B.V. All rights reserved.