engleski

The nature of the hypotelminorheic and its fauna

In 1962, Milan Meštrov defined the hypotelminorheic as “constitué par les sols humides des montagnes, riches en matières organiques et traverses par des filets d’eau courante.” On the basis of studies of Medvednica Mountain (Croatia), Nanos Mountain (Slovenia), and the lower Potomac River drainage (U.S.A.) we refine the definition as (1) a persistent wet spot in a slight depression in an area of low to moderate slope (2) rich in organic matter (3) with a drainage area of typically less than 10, 000 m2 (4) underlain by a clay layer typically from 5 and 50 cm beneath the surface (5) with a characteristic black color derived from decaying leaves which are usually not skeletonized and (6) occurring in a wide variety of geologic settings. Water chemistry (temperature, pH, conductivity, and O2) varied considerably depending on the geologic setting. The presence of clay is likely key to the survival of the fauna as clay retains considerable moisture during periods of drying, and animals can burrow into the clay to escape desiccation. The macroscopic fauna is dominated by amphipods. The combination of high organic matter and relatively large spaces between the leaves may make this a less extreme environment than cave (with low food) or interstitial habitats (with small spaces). It has characteristics of an ecotone, and because of this and its environmental characteristics, it may be an important invasion path into the subsurface.

hypothelminorheic ; wet spot ; ecotone ; macroscopic fauna

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