Effects of temperature and salinity on the growth and biochemical composition of the brown alga Sargassum fusiforme (Fucales, Phaeophyceae)

Temperature and salinity are well-known environmental factors that affect the growth and biochemical composition of brown algae. In this study, we conducted a culture experiment to test the effects of temperature (10, 15, and 20 °C) and salinity (10, 20, 30, and 40 psu) on specific growth rates (SGR) and five compounds (carbon, nitrogen, chlorophyll (Chl) a, Chl c, and fucoxanthin) of Sargassum fusiforme, an ecologically and commercially important species. The results showed that both temperature and salinity had significant effects on SGR and the tissue contents of carbon and nitrogen. Maximal SGR of 6.04% day−1 was achieved at 20 °C and 30 psu. The highest tissue content of carbon (38.19 ± 1.01%) was obtained at 10 °C and 30 psu, while that of nitrogen (2.78 ± 0.09%) was at 15 °C and 10 psu. Significant positive effects of increased temperature were found on both Chl a and Chl c contents. A significant positive effect of increased salinity was only found on the Chl a content. The Chl a and Chl c contents were maximized at 0.50 ± 0.03 and 0.16 ± 0.03 mg g−1 at 15 °C and 20 psu. In addition, significant positive effect of increased temperature and significant negative effect of increased salinity were detected for the fucoxanthin content; this was at a maximum of 2.62 ± 0.04 mg g−1 at 15 °C and 10 psu. These physiological data provide valuable information related to the enhancement of S. fusiforme composition when in cultivation under controlled conditions.