hrvatski

Eksperimentalni sistem cirkulacije vode i mogućnosti njegove primjene u ekološkim istraživanjima

In this study there is a detailed description of a model of closed experimental circulatory water system which is relatively small and simple. The main characteristic of the system is that it allows various modifications which make possible its adaptation to the needs of various investigations as well as control and following and changing of physical and chemical parameters such as: temperature of water, its velocity, intensity of light, type of substrate etc. Because of the above mentioned, the use of this system in ecological investigations is diverse and one of the possibilities is illustrated by the experiment in which we investigated the micro distribution of the nymph Ephemera danica Muller (Ephemeridae, Ephemeroptera) according to the type of substrate used: coarse pebble (23-32 mm), pebble (8-16 mm), sand (0, 5-1 mm) and mud (< 0, 06 mm). The results of these preliminary investigations show that the nymphs of the species mentioned above almost as a rule choose the coarse substrate (coarse pebble and pebble) and avoid sand and especially mud. Thus after the first experiment in pebble and coarse pebble there were found 73.4% and after the second experiment 97.3% of the whole number of animals. On the contrary, in the mud in both experiments only one anima I was found. As all the animals were marked it was possible to follow their movement during the experiment (24 hours). The majority of the animals immediately found their place in the nearest coarse substrate, but during the night some of them (21%) changed the substrate. It can be also seen that the animals mostly moved downstream because of the two small tubs with the same substrate most animals chose the one which is situated downstream.

Laboratorij; cirkulacija vode; primjena; ekološka istraživanja

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