The Optical Properties of Barley Straw Extract: A Possible Algal Inhibitor

Abstract

An environmentally benign, cost-effective means of controlling nuisance algae is in high demand. One solution may be the use of barley straw extract (BSE), which numerous studies have shown to be effective in inhibiting the growth of a variety of algal species. While most studies have focused on which algal species are susceptible to growth inhibition by BSE, the mechanism behind the ability of BSE to inhibit algal growth is unknown. One possible mechanism which has not yet been investigated and which poses a plausible explanation is that the color of the BSE may be blocking enough light to inhibit the growth of algae. An investigation was warranted to examine the role, if any, of the optical properties of BSE in growth inhibition. The effect of the optical properties of BSE was investigated to determine if the shading from the BSE was responsible for inhibiting growth of Heterocapsa triquetra, a common marine dinoflageflate. A growth chamber was designed to provide an environment with controlled irradiance and temperature. FL triquetra was grown under several conditions to determine the effect of the shading on growth. An association was made between the pathlength of the light and the light attenuation, using data from spectral absorbance measurements. It was determined that the optical properties of BSE do not play a role in inhibiting the growth of H. triquetra. Therefore, H. triquetra appears to be inhibited by chemical components as suggested by previous studies. The results of this study are consistent with previous studies in demonstrating the growth inhibition of H. triquetra by BSE. Further, this research provides a foundation for future experiments, which can benefit from the design considerations of this experiment's culture system to expand upon the number of known species which are susceptible to BSE.