Conference Proceedings - IAD

39th IAD Conference, August 2012, Szentendre, Hungary
In rivers and other water bodies of the Ukrainian section of the River Tisa basin
267 macroinvertebrates taxa of 20 taxonomic groups were registered. Among
them Chironomidae larvae – 57 species, Ephemeroptera nymphs – 55,
Trichoptera larvae – 33, Plecoptera nymphs – 29, Oligochaeta – 22, Gastropoda
and Bivalvia – 18, Hirudinea – 11, Odonata nymphs – 8, Amphipoda – 5 and
other Crustaceans – 6 species, and 23 species of other taxonomic groups (1–3
species of each).
On the basis of similarity analysis of the species composition and quantitative
parameters of the benthic fauna at different monitoring points of the Tisa River
basin, it was stated that composition of species inhabiting certain sections differs
depending on localization of these sections. Species composition in all rivers is
formed according to the similar scenarios and of the single biological resource,
peculiar for the mountain rivers of the Transcarpathian region. However rivers
flowing westwards (western hydrological sub-region) show differences in
composition and quantitative relations of the aquatic organisms as compared
with those directed south (eastern hydrological sub-region). Thus, in sub-basins
of the Latoritsa and Uzh Rivers, directed mainly to west, only 10 species of
Ephemeroptera were found, among them Ecdyonurus affinis, E. venosus,
Cloeon simile, Ephemerella mesoleuca, Caenis horaria practically did not occur
in the Tisa River itself and its south-directed tributaries. In the latter this group
was quite diverse, about 40 species. Analysis of other groups of Insecta
(Chironomidae, Plecoptera and Trichoptera) also demonstrated their notably
lower diversity in the Latoritsa and Uzh basins as compared with rivers Rika,
Teresva, Tereblia, Borzhava, White and Black Tisa. Besides, these rivers are
similar in terms of the macroinvertebrates species composition; values of
Sørensen coefficient were between 0.50–0.65. At the same time they differ from
the rivers Latoritsa and Uzh, whereas the latter in turn are similar: Sorensen
coefficient was between 0.5–0.7.
It was supposed (Afanasyev 2006) that the mentioned differences in the benthic
invertebrates composition were conditioned by streams’ different diurnal
warming regimes, flowing along the differently-directed valleys (canyons).
However, similarity analysis on the invertebrates’ composition of the Romanian
(left-bank, mainly northern-directed; Vişeu, Iza, Sepintsa) and Ukrainian (the
right-bank, mainly southern-directed) tributaries of the Tisa River revealed that
bottom fauna of all these rivers was similar. In the Latoritsa and Uzh river basins,
sources are located at lower altitudes, therefore taking this fact into account it is
supposed that the absence of the “highland” type of the water bodies leads to
somewhat impoverishment of the species composition as compared with rivers
with sources at high altitudes. Besides, this can be conditioned by other reasons
of historical nature, particularly by belonging of these rivers to the basin of the
Upper-Tisa Lake, which existed from Pliocene to the middle Pleistocene
(Afanasyev, in print).
In the upper sections of rivers of the western hydrological sub-region (low-water
season, without pollutions, invertebrates were distributed as follows: Plecoptera
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