Fluctuation in density of ciliates in Bukan dam reservoir ,Zarrinehrud, Iran

 The abundance and species composition of ciliates were analyzed in the Bukan Dam Reservoir (West Azerbaijan, Iran) from January to December ۲۰۰۸. Surface water samples were collected at monthly intervals from the middle (Stations ۱ and ۳) and shallow (Stations ۲ and ۴) areas of the lake. Three samples were taken in the water column using a ۵-litre sampler. Totally ۳۰ liters water was collected, ۲۰۰ ml of which was fixed immediately with ۸.۶ ml of a saturated HgCl۲ solution and stained with ۰.۰۴% bromophenol blue. Three subsamples were counted in a ۵-ml chamber and examined with a microscope (۱۰۰ x) as well as Chlorophyll a and a few ecological parameters such as dissolved oxygen, pH, transperancy and water temperature were measured. Totally ۵۰ ciliates species were found in Bukan Dam Reservoir. Regarding the density, a high-density period was detected from January to April with a mean density of ۲.۸۶ x ۱۰۳ cells.l-۱ Ciliata at stations ۱ and ۳ and ۴.۱۶ x ۱۰۳ cells.l-۱ at stations ۲ and ۴. The high density of ciliate in summer may be due to the increase in the density of bacteria and moderate metazooplankton as a result of the appearance of non-edible algae . The ciliata occurring at the highest densities were Coleps tessellates, Didinium nasutum, Paradileptus elephantinus, Stentor polymorphus, Zosterograptus labiatus, Paramecium bursaria, Cyclidium citrullus, Vorticella campanula, Halteria grandinella and Aspidisca costata. The maximum and minimum chlorophyll a values observed at the reservoir water were ۱۰.۳۹ µg.l-l and ۱.۰ µg.l-l being obtained in May and Octobor respectively.

Keywords:

Ciliata , density , West Azerbaijan , bukan dam reservoir , Iran