E.Ü. Su Ürünleri Dergisi 2006 E.U. Journal of Fisheries & Aquatic Sciences 2006 Cilt/Volume 23, Sayı/Issue (1-2): 113–116 © Ege University Press ISSN 1300 - 1590 http://jfas.ege.edu.tr/ The Effect of Food (Scenedesmus acuminatus (von Lagerheim) R. H. Chodat) Densities and Temperature on the Population Growth of the Cladoceran Ceriodaphnia quadrangula (O. F. Muller, 1785) *Sevgi Savaş, Ömer Erdoğan Suleyman Demirel University, Faculty of Fisheries, Egirdir, Isparta, Turkey *E mail: segi68@yahoo.com Özet: Cladoceran Ceriodaphnia quadrangula (O.F. Muller, 1785)’nın populasyon artışı üzerine sıcaklık ve besin (Scenedesmus acuminatus (von Lagerheim) R. H. Chodat) yoğunluğunun etkisi. Bu çalışmada, Ceriodaphnia quadrangula’nın populasyon artışı üzerine sıcaklık (20, 25 ve 30 ºC) ve farklı besin (Scenedesmus acuminatus) yoğunluğunun (15, 30, 45, 60 ve 75x10 4 h/ml) etkisi incelenmiştir. Deneme 16 aydınlık:8 saat karanlık ışık uygulamasında gerçekleştirilmiştir. Deneme başında, farklı besin yoğunlukları içeren her bir tüpe 1 adet 24 saatten genç birey konulmuş, birey sayısı ve büyüme hızı 25 gün süre ile belirlenmiştir. En yüksek birey sayısı (21,433±0,750 birey/ml) ve büyüme hızı (0,240±0,004) 25 ºC’de 45x10 4 h/ml’de belirlenmiştir. Besin yoğunluğunun artması, Ceriodaphnia quadrangula’nın birey sayısı ve büyüme hızını arttırmıştır. Farklı besin yoğunluklarının birey sayısına etkisi istatistiki olarak önemli (P<0,05), 20-25 ºC arasındaki sıcaklığın önemsiz (P>0,05) olduğu bulunmuştur. Anahtar Kelimeler: Ceriodaphnia quadrangula, Scenedesmus acuminatus, besin yoğunluğu, sıcaklık, populasyon yoğunluğu. Abstract: In this study, the effect of the different concentration of Scenedesmus acuminatus (15, 30, 45, 60 and 75 x 10 4 cell ml -1 ) and temperature (20, 25 and 30 ºC) on the population growth of Ceriodaphnia quadrangula were investigated. The experiment carried out a photoperiod of 16 hours light:8 hours dark In the beginning of the experiments, 1 individual <24 h old were put on each vessel, number of the individual, growth rates were determined during 24 days. The peak population density and the growth rate were obtained at 45 x 10 4 cells ml -1 at 25 ºC. Increasing the food concentration was increased number of individual and growth rates in Ceriodaphnia quadrangula. The effect of different food concentration on number of the individual were statisticaly significant (P<0,05), temperature between 20 and 25 ºC were found insignificant ( P>0,05). Key Words: Ceriodaphnia quadrangula, Scenedesmus acuminatus, food concentration, temperature, population density. * Bu çalışma S.D.Ü. Bilimsel Araştırma Projeleri Yönetim Birimi tarafından desteklenmiştir (SDUAF -849 YDL). Introduction Freshwater zooplanktons are mainly composed of protozoans, rotifers, cladocerans and copepods. Cladocerans, in term of biomass, are often the dominant groups (Benider et al., 2002). The most important environmental factors controlling cladocerans growth and reproduction are temperature, food quantity and quality. Cladocerans by virtue of their small size and short generation times, respond rapidly to changes in algal food density ( Nandini et. al., 1998; Nandini and Sarma, 2000; Nandini and Sarma 2003). One the most important variable affected by changing food level is the population growth rate. The effects of food on the dynamics of cladoceran species have been a well-researched issue (Jana and Pal, 1983; Gliwicz and Guisande, 1992; Boersma and Vijverberg, 1996; Nandini and Rao, 1998; Ovie and Egborge, 2002; Rose et al., 2000; Benider et al., 2002; Nandini and Sarma, 2000; Nandini and Sarma, 2003; Alva-Martinez et al., 2004). However, most studies have focus on Daphnia species and few studies have appeared on dynamics of smaller cladocerans such as Ceriodaphnia, Moina and Simocephalus (Jana and Pal, 1985; Ramirez et.al., 2002; Rose et al., 2002; Abrantes and.Goncalves, 2003). Especially, little information is available on the effect of food level and temperature on C. quadrangula in growing culture. Therefore, the aim of the present work was determined effect of food level and temperature on C. quadrangula using population growth to asses performance. Materials and Methods The Ceriodaphnia quadrangula was isolated from the lake Karacaören-Antalya-Turkey, and maintained for at least 6 months prior to experimentation. For routine maintenance as well as the experiments, we used well water. Scenedesmus acuminatus was cultured in 6 l bottles using Bold’s basal medium. Algae in the log phase of growth was centrifuged and resuspended in well water. The density of this stock concentrate was determined using “neubauer” counting chamber. An initial test was conducted to determine the food concentrations (15 x 10 4 , 30 x 10 4 , 45 x 10 4 60 x 10 4 and 75 x 10 4 cells ml - 1) and temperature (20 °C, 25 °C and 30°C). In a preliminary, the population did not grow 30°C and a food concentration of 75 x 10 4 cells ml -1 . For the population growth experiments, we were designed based on the results of the pilot study, which indicated that 15 x 10 4 , 30 x 10 4 , 45 x 10 4 ve