Abstract:
The present study is part of some recent ecological investigations carried out in the Danube Delta Biosphere Reserve in order to assess the risks to biodiversity and the impact of natural and anthropogenic factors on characteristic ecosystems. Meadows and agro-ecosystems have been taken into study, aiming to investigate qualitatively and
quantitatively the oribatid communities, diversity and distribution of species depending on the type of habitat. In terms of fauna 60 species have been identified belonging to 43 genera and 31 families of the suborder Oribatida Dugès, 1834. The family Ctenacaridae Grandjean, 1954, genera Ctenacarus Grandjean, 1939 Exochocepheus Woolley and Higgins, 1968, also the species Ctenacarus araneolus (Grandjean, 1932), Exochocepheus laticuspis (Balogh and Mahunka, 1965) and Oribatula (Zygoribatula) andrianovae (Bulanova-Zachvatkina, 1967) were recorded for the first time in Romanian fauna. The global average abundance and number of species varies widely from one sampling site to another, even in the case of similar ecosystems. However, in the non-grazing meadows, generally higher values of these parameters were observed compared to cultivated soils and pastures. From a qualitative point of view, notable differences were observed in the species composition of the oribatid communities in meadows and crops, even if they were located in the immediate vicinity. On the other hand, a degree of similarity was noted in the species composition and structure of oribatid coenoses in the agro-ecosystems, regardless of the type of crop and soil.
