İzmir Körfezi’nden izole edilen Cylindrotheca closterium (Ehrenberg) Reimann & J. Lewin, 1964 türünün büyümesi üzerine ışık, sıcaklık, nütrient ve tuzluluğun etkileri

Abstract

Cylindrotheca closterium is one of the diatom species that is dominant particularly in spring and summer in Izmir Bay and Aegean Sea. In this study, growth kinetics of Cylindrotheca closterium have been studied under different temperature, light intensity, nutrient concentrations and salinity conditions. Initially, temperature-light experiments were carried out and optimum temperature is determined to be 18 0C for this species. Obtained results at 18 0C are µmax= 1.97±0.167 d-1 for the maximum specific growth rate and KI=0.048± 0.028 for the half saturation constant. Then, six light intensities (0.9, 0.88, 0.74, 0.46, 0.2, 0.07 *100 μmol photon/m2s) and seven salinity concentrations (5, 10, 15, 20, 25, 30 ve 35 %0) were investigated on the growth rate of Cylindrotheca closterium under optimum temperature. The specific growth rate has been calculated to be 2.012 d-1 at 15 %0 salinity which is determined to be the optimum concentration. Exponential growth rates are obtained in semi-batch culture by measuring Chl a values and corresponded nutrient concentrations which are statistically valid (p<0,05) in regard to Monod equation (µ=µmax*S/KS+S) and µmax values, a parameter of Monod equation, are calculated for different concentrations of ammonium, nitrate, reactive phosphate and reactive silica are 2.48±0.61 d-1, 1.92 ±0.3 d-1, 2.1± 0.05 d-1 and 1.97± 0.20 d-1, respectively. KS values, which are another parameter of Monod equation, that are obtained for each nutrient are 17.84±14.4 μM NH4+-N, 27.3± 19.04 μM NO3--N, 0.25±0.04 μM PO4-P and 0.3±0.24 μM Si, respectively. As a result of global warming, temperature is expected to be risen 6 0C in 2100. The impacts of this increase on the growth rate of Cylindrotheca closterium species in Izmir Bay is calculated, considering this scenario. Nitrogen is determined to be the only restricting compound that inhibits growth during 52 weeks by a study that is conducted by Sunlu et al., (2007). Consequently, the growth rate of the species didn’t decline under 1.5 d-1 during this period of time.