L. Forró szerk.: Miscellanea Zoologica Hungarica 9. 1994 (Budapest, 1994)
Andrikovics, S.; Hadnagy, T.: Ecological evaluation of aquatic invertebrates distribution of Apátkút Creek (Visegrádi Mountain, Hungary) in winter
transects. Detritus accumulates on these areas, but it can be found among or under rocks on faster flowing area. It collects three or four smaller creeks on the right and left side. These inflows usually dry out during the summer. The winter in this year was extremly cold and prolongated. So in the beginning of March the temperature was hardly above freezing point, the temperature of the water was 0, 1,2, 2.5 °C. In the first period pilot samplings were taken, 50 samples two times - on 1st 12, 1984. and 17th 12. 1984. along the full length of the creek in order to gather many ecological information and to separate 7 areas. These are as follows: I. Pilisszentlászló; II. House with chimney; III. Clearing; IV. Apátkút-mine; V. Hunting-lodge; VI.Magdolna-spring; VII. Visegrád (Fig. 1). Samples were taken 8 times from December 1984 to March 1985. These transects proportionally divide the whole creek. If we draw a map of ecological circumstances of the areas we explore not only the mosaic-structure of certain areas of the creek but we can also compare them. We can interpret changes of species number and individuals of the macrofauna along the creek on the basis of change of ecological circumstances. We accomplished invertebrate samples with water-samples to determine dissolved oxygen content and we measured water current. Sampling dates are as follows: 25th 12, 1984. in Visegrád, 22nd 01, 1985 at Magda-spring, 23rd 02, 1985 at Hunting lodge, 28th 02, 1985 at Apátkút-mine, 03rd 03, 1985 at Clearing, 07th 03, 1985. at House with chimney, 07th 03, 1985 in Pilisszentlászló. Material and methods Three kinds of methods were used at the same time: we measured the water velocity, the amount of the dissolved oxygen and we collected aquatic insect larvae, too. The current of water is not steady, actually it has particular pulsation, that is why the measuring instrument registers in a certain range of the scale during the measurement. As a result we registered average values of this range. We measured areas with different water velocity, and hence we used two kinds of propellers: one marked 3-24245 and the other marked 5-23883. We set up the first one on the faster flowing stretches and the second one on slower flowing stretches. The wings of 3-24245 propeller wind less in direction of rotation, but the wings of 5-23883 propeller form nearly one thread, so even the slower current can move it. Before starting the measurement we checked the calibration of the propellers: we accomplished measurement of water velocity at one point with both propellers and their values were the same. The determination of dissolved oxygen content took place according to the Winkler-method (Felföldy 1974). The macrofauna was collected with a special net. The frame of the net was a 20x20 cm, its net was 60 micron mesh-size. Each sample was taken from exactly determined area of the creek (0.1 m 2 ). The surface of the water was frozen in 10-20 cm - thick - layer in many places, but it was not frozen to the bottom. As we broke up the ice we did not stir up the bottom, if we did not move the stones. Than we collected the larvae from 0.1 m 2 territory. At the sampling sites we accomplished the following ecological observations and measurements: average velocity of water: the measurement was done with OTT Current Meter instrument at 25 transects. In case of other places we estimated the water velocity comparing with the result of the previous measurements. size of stones: we estimated the diameter of the stones, too, it is also an approximal average value, but the data registered in the different sample sites are proportinal to one another, depth of water temperature: water and air temperatures were measured with a thermometer with 0.1 °C scale, other data: detritus, wood branches, leaves, pollution on the sampling place were registered. The collected material can be found in the scientific collection of the Department of Zoology of Eszterházy Károly Teachers' Training College.
