Resting Egg Production and Fatty Acid Enhancement in the Waterflea, Ceriodaphnia quadrangula, by Using Combination of Light Regime and Food

Abstract

Combined effects of different light regimes, 6L:6D and 12L:12D (hours light : hours dark, L:D) and algal foods of Scenedesmus quadricauda (S) and Chlorella vulgaris (C) on ephippia production and fatty acid (FA) profile of Ceriodaphnia quadrangula were investigated. The highest resting egg production, density, and specific growth rate were obtained with 6L:6D+S; followed by 12L:12D+S treatment. The C16:0 varied from 16.2 to 22.16 mg/g dry weight (d.w.); C18:1n−9 from 11.03 to 14.94 mg/g d.w; C18:2n−6 from 9.79 to 20.24 mg/g d.w; and C18:3n−3 from 6.98 to 16.02 mg/g d.w. The amounts of C20:4n−6 (4.36 mg/g d.w) and C20:5n−3 (3.35 mg/g d.w) at 6L:6D+S were highest compared to other treatments. The maximum saturated fatty acids and monounsaturated fatty acids were obtained at 6L:6D+C while maximum polyunsaturated fatty acids observed at 6L:6D+S and 12L:12D+C. The resting egg production and FAs profile could be improved when the frequency of changes from light to dark were increased. Our findings also indicate a significant increase in the quantity of C18:3n−3 in C. quadrangula populations during resting egg formation, hence, implying that manipulation of light regime and algal food can improve performance of C. quadrangula as a live food in aquaculture industries, especially for larval feeding.