Zoran Marković, Ivana Živić, Vesna Poleksić, Zorka Dulić and Marko Stanković

1. Biological Characteristics of Two Small Aquatic Ecosystems – Uncovered Wells on the Experimental School Estate of the Faculty of Agriculture University of Belgrade Zoran Marković, Ivana Živić, Vesna Poleksić, Zorka Dulić and Marko Stanković Faculty of Agriculture, University of Belgrade, Belgrade, Serbia and Montenegro

2. These investigations were carried out as a part of Project “WATERWEB” FP 6 INCO-West Balkan (Resources Strategies and Drought Alleviation in Western Balkan Agriculture)

3. The aim of this investigation was to determine water quality of two uncovered wells using aquatic invertebrates - zooplankton and bottom fauna, as bioindicator organisms.

4. uncovered well No.1

5. uncoveredwell No. 2

6. Can water from these sites be used for irrigation of cultures, as well as a water supply for aquaculture experimental ponds at the Faculties Experimental School Estate?

7. Material and Methods Investigation were carried out during 2005, monthly, from April to October

8. Sampling of aquatic invertebrates were performed using: • Plankton net (75mm) for zooplankton sampling • Eckman – Birge bottom grab sampler for bottom fauna sampling

9. Water quality was determined using Pantle – Buck method - saprobity index “S” List of bioindicator organisms by Ortendorfer & Hofrat (1983) was used for water quality analyzes

10. Additional investigation Water field kit was used for measurements of: • water temperature • dissolved oxygen • oxygen saturation • conductivity • Measurements were performed at 7 different depths: 0.1m, 1m, 2m, 3m, 4m, 5m and 6m

11. Results • We have determined 40 taxa of zooplankton and 5 taxa of macrozoobenthos. • Zooplankton was more diverse than macrozoobenthos that was expected due to the fact that zooplankton is a dominant animal component in stagnant aquatic ecosystems

12. Using zooplankton as bioindicator organisms, saprobity index varied from 1.54 to 1.78 (well No.1) and from 1.30 to 1.87 (well No.2). Acording to these data water quality was between I and II class

13. Using macrozoobenthos organisms as indicators of water quality, calculated saprobity index showed that water quality was in the II class in both wells. Saprobity index varied from 1.70 to 2.30 in well No.1 and from 2.03 to 2.20 in well No.2.

14. Data analysis of physical and chemical characteristics of water of investigated wells have shown: • changes along the water column - from the surface to the bottom of the wells • seasonal changes (from April to October)

15. Water temperature • a general pattern of decline from surface to bottom of wells. • highest temperature has been observed in July and August as well as the biggest fluctuation of water temperature, from 10.10C to 24.1 0C (well No.1, July) and from 11.5 to 22.0 0C (well No.1, August).

16. Dissolved oxygenand oxygen saturation • decline with depth during all investigation months • sharp decline in oxygen content at the depth of 2m • from 3m to 6m there has been continuous low oxygen content during the whole investigation period • no oxygen in August at depth 2 - 6m

17. Water conductivity • slightly higher content of mineral maters • gradual increase with depth, in both wells • conductivity had overall small fluctuations • during the whole investigation period, conductivity was higher in the well No.2 than in well No.1

18. Conclusions The results of qualitative analysis of zooplankton and bottom fauna, as bioindicators of water quality, show that water was between I and II class (oligosaprobic and -mezosaprobic)

19. According to these data two investigated small aquatic ecosystems – uncovered wells, could be used for irrigationof cultures, as well as a water supply for aquaculture experimental ponds