Assessment of light intensity and salinity regimes on the element levels of brown macroalgae, Treptacantha barbata: Application of response surface methodology (RSM)

Abstract In this research, the effect of light intensity and salinity regimes on the element levels of Treptacantha barbata (formerly Cystoseira barbata) was studied, and the elemental compositions of this brown alga collected from wild stocks also compared with cultured ones. In culture trials, 11 different experiments that have ranges of light intensity as 50 to 150 µmol photon m-2s-1 and salinity as 24 ‰ to 42 ‰ were designed according to response surface methodology (RSM). Our results show that the element accumulation with changes of light intensity and salinity on the T. barbata was modeled. Most of the elements were affected by the salinity instead of light intensity. All macro and microelements were detected within the recommended dosages and exposure limits. In toxic elements, the least accumulations of Al, As, Cd, and Pb were observed in low light and salinity. Also, the levels of all toxic elements, including trace elements that exceed limits, can be reduced with using these models. The most effective experiment was found as 52.0001 µmol photon m-2s-1 light and 24.086 ‰ salinity for minimized toxic element accumulation on T. barbata with 0.869 desirability.