Antioxidant and photo-physiological acclimatisation in tropical macroalgae at sites with distinct nutrient levels

Abstract. Gopeechund A, Bhagooli R, Neergheen VS, Bahorun T. 2023. Antioxidant and photo-physiological acclimatisation in tropical macroalgae at sites with distinct nutrient levels. Indo Pac J Ocean Life 7: 79-90. The antioxidant efficacy, Total Phenolic Contents (TPC) and Total Flavonoid Contents (TFC) were investigated at Gis Gris with Lower Nutrient levels (LN site) and Bain boeuf with Higher Nutrient levels (HN site) around Mauritius Island. A field-based 7-days transplantation manipulation of Turbinaria ornata, Gracilaria salicornia and Sargassum obovatum between HN and LN sites was conducted to test the impact of different nutrient conditions on their physiology. All the species had lower antioxidant efficacies, TPC and TFC at LN compared to HN site. The glutathione peroxidase and catalase were more sensitive at reflecting the lower oxidative stress at LN site and acclimatisation to oxidative stress occurring at the HN site. ETRmax and ? were significantly higher in all species at HN site. The quantum yield Fv/Fm increased in S. obovatum only, after 7 days of transplantation at HN site, while, T. ornata and G. salicornia had similar adaptability to photo-physiological stress at both sites. NPQmax decreased in S. obovatum but increased in T. ornata transplanted to HN site, indicating increased photo-protection at HN site. Lagoons with higher nutrient levels may enhance macroalgal capacity to deal with oxidative stress, thus lowering the need for further photo-protection.