Identification and Abundance and distribution of Zooplankton in Laar reservoir (Tehran)

Subject Areas : New Technologies in Aquaculture Development

Received: 2020-12-08 Accepted : 2020-12-08 Published : 2012-02-20

Keywords: Density, Tehran, Dispersion, Laar reservoir, Keywords: Zooplankton,

Abstract :

Abstract[1] For optimum management in Laar Lake, limnological and biological parameters such as identification, density and distribution of zooplanktons were done during 6 months from June to October in 2006. Samples were taken by simple plankton net (55 μm mesh size) from various depth layers (0-5 m, 5-10 m, 10-20 m, 20-30 m, 30-40 m) and were fixed with formalin 4%. In the laboratory they were studied with inverted microscope. The order of Cladocera was predominant, and comprised 48.71% of population annually, predominate genera were Bosmina sp., Daphnia pulex, Daphnia longspina and embryonic Cladocerus. The order of Rotatoria comprised the second position with genera of Asplanchna sp., Collotheca sp ., Notholca sp., Philodina sp., Polyarthera sp . and Syncheata sp . (percentage composition 41.81). Ciliophora order was represented by one genus, Tintinnidium sp., (percentage composition 6.21) was at third position, Copepoda with 3.12 percentage composition two genera Cyclops and Copepoda Naupli. In this survey, we distinguished 13 genera in 4 zooplanktonic orders. For the sampling all monthly, mean of dominant zooplanktonic density belonged to Cladocera order (6311.83±123.40 ind./m3) while they reached minimum in September by (1875±1475.12 ind./m3) Rotatoria were the second level with mean of 5411.66±115.39 ind./m3 reaching minimum with 4993.75±73.10 ind./m3 were in September. Non-parametric analysis Kruskal-Wallis test and Mann-Whitney test showed that there were statistical significant differences (p <0.05) between Zooplanktonic density in different stations and months, but there was not any statistical significant difference between different depths (p >0.05). Biological studies indicated that this reservoir has low potential for planktonic generation and due to geographical location of this dam, remarkable temperature differences can be observed in different years especially in fall and winter, which is biologically important. *- Corresponding Authors; Email: [e-mail]