Nutrient effects on the growth rates of marine diatom Chaetoceros gracilis Schutt

The aim of this research is to reveal the detailed information on growth kinetics of Chaetoceros gracilis Schutt from the results of nutrient enrichment experiments under batch culture conditions. C. gracilis Schutt was isolated from Izmir Bay (Turkey). The studies were performed under optimum light and temperature and nutrient saturated conditions except the nutrient which is investigated. Experiments were conducted in a constant temperature room at 28 degree C and irradiated at 1300 ftCd (foot-candle) by daylight fluorescent lamps. Cultures were maintained on a 12:12 light:dark cycle. For stock cultures and batch culture experiments, f/2 and h/2 mediums were used as described by Guillard (1975). Exponential growth rates were calculated according to Guillard 1973. The exponential growth rates were plotted against corresponding each nutrient concentrations. Monod curve (Monod, 1942) parameters were calculated by using transformations and the least square method. Ks (Half Saturation Constant) values calculated for each of nutrients were found as follows; 0.496 mu mol NO sub(3)-N L super(-1); 0.862 mu mol NH sub(4)+-N L super(-1); 1.045 mu mol PO sub(4) super(-3)-P L super(-1) and 0.558 mu mol Si L super(-1). Concerning the same nutrients, values of maximum growth rate were found as 1.611 day super(-1), 1.332 day super(-1), 1.662 day super(-1) and 1.757 day super(-1) respectively.