The effect of temperature on batch growth of Gracilaria salicornia and Gracilaria changii / Thurga Murali

Thurga , Murali (2024) The effect of temperature on batch growth of Gracilaria salicornia and Gracilaria changii / Thurga Murali. Masters thesis, Universiti Malaya.

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Abstract

Seaweed (or macroalgae) serve as the foundation of productive food webs containing economically valuable species and their influence extends far beyond the shallow water in which they live. They are also effective at carbon sequestration, converting roughly half of the carbon dioxide in the atmosphere into organic compounds that are used to produce critical cellular constituents and increase energy production. Despite the importance of algal diversity and carbon sequestration, knowledge of how global or ocean warming affects them is still limited. Temperature can affect the development and photosynthesis of algae, particularly their biochemical and physiological processes. This study looked at how increased temperature impacts the growth of seaweeds, specifically Gracilaria species, a well-known and significant agarophytic genus in Malaysia, in terms of physiological and biochemical features, as well as the highest temperature tolerated by the species. The seaweeds were grown under four different temperatures; 28±1.0, 32±1.0, 36±1.0 and 40±1.0oC. ANOVA analysis of G. salicornia and G. changii showed a significant difference (P < 0.05) on the growth between the controlled temperature and elevated temperature treatments for each point, particularly at 40oC, indicating that higher temperature could negatively affect the growth and photosynthetic activity of Gracilaria spp. The highest Fv/Fm was recorded at 28oC for G. salicornia and 32oC for G. changii, which are 0.6968 and 0.6158, respectively. A further increase of temperature at 40oC led to a huge decline from 0.6256 to 0.0254 and 0.5798 to 0.0904 for samples G. salicornia and G. changii, respectively. As temperature increased, a declining trend was observed for gel strength, melting temperature, and gelling temperature of G. salicornia and G. changii up to the final day of the experiment. The reactive oxygen species (ROS) levels in both G. salicornia and G. changii fluctuated between the fifth and fifteenth day. The physiological and biochemical properties of Gracilaria spp. have been affected when different temperature stresses were introduced.

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