%0 Book part %A Kecskés Attila %D 1997 %G English %B Tiscia monograph series %B The Cris/Körös rivers' valleys : a study of the geography, hydrobiology and ecology of the river system and its environment %@ 1418-0448 %T Occurrence of amphibious bugs, water bugs and ground bugs in the catchment area of the Crişul Alb, Crişul Negru and Crişul Repede rivers %U http://acta.bibl.u-szeged.hu/10151/1/tiscia_mono_002_275-286.pdf %X Research carried out so far on Ihis subject demonstrates the presence of twenty bug species in the catchment area of the three Cri§ rivers. Due to our current studies we may add nineteen new species to the bug fauna of the region and confirm the existence of eighteen previously mentioned species. The thirty-seven species found by us are represented by 1048 collected samples belonging to the following taxonomic categories/orders: Hydrocorisae: 539 samples of thirteen species Amphibiocorisae: 398 samples of thirteen species Saldidae: 111 samples of eleven species In this work we shall describe species living in rivers and we shall try to give a proper explanation to the frequency or infrequency of certain species. Our most important conclusion referring to the distribution of different species is that their diversity is much higher for natural reaches, the water-bugs are more numerous and represented by more species in stagnant waters, and the diversity of the amphibious bugs is the highest on middle and lower reaches. The greatest variety of ground bug species are to be found on upper reaches or stony river banks. These species are not threatened by extinction, but their existence is closely connected with the natural conditions of rivers. They don't appear sensitive to industrial water pollution, as demonstrated by the high number of samples collected in polluted water near the city of Petru Groza.