Brown seaweed, Padina boryana is found along the coast of Terengganu, Malaysia and may serve as a potential heavy metal biomonitor in the coastal zones. To better understand the impact of heavy metal pollution on P. boryana at varying seawater pH levels, the combined effect of zinc (Zn) and pH on its growth rate and chlorophyll content was investigated in laboratory exposures. After exposure for 21 days in a mixed treatment of 6 pH variations (4 to 9) and three Zn concentrations (30, 150, 300 ppb), maximum growth rate was observed in controlled treatments at pH 8 with no added Zn, whereas treatments at pH 4 and 9 showed negative growth rates after 18 days. The growth rate and chlorophyll content of P. boryana decreased significantly with an increase in Zn concentration. At pH 6, 7 and 8, P. boryana showed significant decreases (p < 0.05) in growth rates and chlorophyll content in all concentrations of Zn compared with control plants (no Zn). At pH of 6.0 and below, controls were also affected with significantly reduced growth rates and chlorophyll contents while Zn treated seaweed showed significant effects compared to these controls. The effect of pH and Zn on all measured factors was obvious on Day 6 onwards, whereas the interaction effect between them was significant on chlorophyll content throughout the experiment. From Day 9 onwards, the growth rate and chlorophyll content showed significant correlation among each other.
Al-Awlaqi N. A. N., Shazili N. A. M. & Yusoff N. M., 2019. The combined effect of zinc and pH on growth rate and chlorophyll content of brown seaweed, Padina boryana. Malaysian Journal of Analytical Sciences 23 (6): 1018 – 1029. Article.