| Author Title Journal |
Dudziak J (1956) Observations on the occurence and ecology of Crenobia alpina (Dana) in western Tatral. Polskie Arch Hydrobiol 3: 11-42 |
Abstract / Notes
Results of investigations on occurrence and ecology of Crenobia aplina (Dana) in Western Tatras are submitted. Certain observations in Cracow Upland have been considered also. On the basis of research performed it has been established that 2 factors are decisive for occurrence of C. alpina: (1) an environment free of artificial pollution and possessing small contents of organic substance, (2) thermic conditions. Temperature optimal for this triclad, is 5[long dash]7[degree] C. Presence of a triclad colony composed of specimens at various stages of growth was considered as criterion for occurrence of C. alpina in the given aquatic environment was not accidental. Kind of substratum (mineral slime, sand, aquatic vegetation, stones, massive rock) is of no conspicuous importance for occurrence of planaria under consideration. C. alpina prefers to inhabit the current with speed to 0.3 m/second, and evades waters with an impetuous current. In the area investigated the concentration of the hydrogen ions in the environment varies from 6.8 to 8.2 pH. The value 6.8 was found once. All other measurments of pH, gave values higher than 7. Within oscillations established, pH of water does not exercise any evident influence upon planarian fauna. Planaria under consideration occurs in underground channels of springs. As is well known from investigations performed in western Europe, O2 content of water in such environment is not great. Thus, we may draw the inference that this planaria is not susceptible to low content of O2 in water. Neither does light nor presence of other living organisms in environment affect in an evident manner occurrence of this planarian. In order to explain the presence or absence of the planarian, no unknown ecological factors need be assumed. Territories situated northwards of Carpathian Mountains were inhabited after Glaciation Period by C. alpina which, starting from the south, that is from the arch of the Carpathians, moved northwards. This triclad may considered as a glacial relic only in stations beyond the Carpathian. The picture of its general distribution in these territories is influenced today most strongly by mechanical factors and especially by activity of man. Absence of Polycelis felina in the Tatras and in other areas of Poland is not caused by ecological factors. It results from historical, geographical causes.| Home page -- (Main hierarchy) |