Effect of shrimp farm effluent (SFE) on growth, survival, regeneration, and biochemical composition in indigenous red seaweed Gracilaria corticata var. cylindrica

The growth and biochemical profile of the red seaweed Gracilaria corticata var. cylindrica was evaluated after in vitro cultivation with effluent from a shrimp Litopenaeus vannamei farming pond. Seaweeds were cultivated for 21 days in sterilized seawater enriched with shrimp effluent with 5 different concentrations (0.1, 1, 10, 50, and 100 mL L−1). Fragments with 50 and 100 mL L−1 showed a higher significant growth rate of 3.53 ± 0.08% and 3.7 ± 0.55% respectively compared to sterilized seawater as control (2.5 ± 0.15%). Survival and regeneration of fragments were higher in the treatments 10, 50 and 100 mL L−1. A 100% survival was observed in 10 and 100 mL L−1, while 100-mL L−1 showed 100% regeneration in fragments. The number of branchlets developed per fragment was observed higher (2.33 ± 0.52) and (2.23 ± 0.05) in 50 and 100 mL L−1 respectively. A 50 mL L−1 showed the highest (124.45 ± 9.28 µg g−1) chlorophyll-a, and 100 mL L−1 showed the highest (54.5 ± 5.42 µg g−1) chlorophyll-b content. Agar yield (2.8 ± 0.32% FW), total sugar (72.6 ± 2.7%), and 3,6-anhydrogalactose (8.77 ± 0.63%) was observed highest in 100 mL L−1 treatment of shrimp effluent, while sulphate content (1.5 ± 0.8%) found higher in 50 mL L−1. Results showed that effluent treatments positively affected G. corticata var. cylindrica growth and biochemical composition, especially 50 and 100 mL L−1, which could be considered a good bio-stimulator for the making of the seedling. This work presents the potential use of effluents from shrimp cultivation as fertilizer, improving the growth and seedling production for sustainable cultivation of endemic red seaweed Gracilaria corticata var. cylindrica.