Water Physicochemical Properties Influence the Production, Nutritional Composition, and Antioxidant Activity of Gracilaria tenuistipitata From the Northern Bay of Bengal, Bangladesh

This study investigates the influence of water physicochemical properties on the growth, production, nutritional composition, and antioxidant properties of Gracilaria tenuistipitata, cultivated at two different sites (Gangamati and Hazipur) along the northern Bay of Bengal, Bangladesh. The water quality parameters were monitored weekly. Results revealed that the Gangamati site is characterized by significantly higher (p < 0.05) salinity (14.75 ± 4.89 ppt), transparency (60.50 ± 9.57 cm), and total dissolved solids (6154.90 ± 1492.50 mg/L) compared to the Hazipur site. The Gangamati site significantly (p < 0.05) outperformed the Hazipur site in terms of daily growth rate and production. Furthermore, proximate composition analysis indicated significantly higher (p < 0.05) protein (25.06 ± 0.90% DW), lipid (1.22 ± 0.05% DW), fiber (7.03 ± 0.76% DW), and carbohydrate (38.41 ± 0.80% DW) contents in seaweed from the Gangamati site. The mineral content of G. tenuistipitata was also influenced by the culture site significantly (p < 0.05). Amino acid analysis demonstrated superior protein quality in Gangamati seaweed, with significantly higher levels of essential (77.286 ± 0.06 mg/g) and nonessential (95.243 ± 0.07 mg/g) amino acids than the Hazipur site. The fatty acid profiles varied significantly between the two sites, with seaweed from the Gangamati site exhibiting higher levels of unsaturated fatty acids (41.27 ± 0.05%) compared to Hazipur, indicating superior nutritional lipid quality indices. Bioactive compounds were significantly higher (p < 0.05) in Gangamati seaweed, along with higher antioxidant activity. Overall, these results indicate that the Gangamati estuary provides a better environment for the cultivation of G. tenuistipitata, resulting in seaweed with superior nutritional and bioactive properties.