COMPARATIVE ANALYSIS OF SEAWEEDS, REARED WITH OYSTERS IN CAPTIVE ENVIRONMENT

Abstract

Two seaweed species, Gracilaria verrucosa and Ulva lactuca, as well as oysters, Crassostrea belcheri, were co-cultured under different treatments for 120 days in captivity. The study assessed the water quality parameters, growth performance, and proximate and biochemical composition of the organisms. G. verrucosa and C. belcheri were co-cultured (T1), U. lactuca and C. belcheri co-cultured (T2), and G. verrucosa, U. lactuca, and C. belcheri were cultured independently (C1, C2, C3), with three replications in each case. The experiment's conclusion involved a comparison of the treatments and control group's oyster growth, survival, and water quality. Apart from that, both indoor and outdoor seaweeds and oysters were compared to assess their proximate and biochemical indices. The salinity ranged from 32.75 to 22.05 psu, the dissolved oxygen from 7.19 to 4.22 ppm, and the pH from 8.72 to 6.45 ppm for each treatment. Significant relationships between salinity, conductivity, and temperature were found using principal component analysis. Significant variations were seen in the growth rates of the two seaweeds, U. lactuca exhibiting the highest live weight gain and specific growth rate in T2. The percentage of surviving oysters varied from 60% to 80%, with T2 showing the fastest growth rates. The seaweeds' moisture, ash, protein, carbohydrate, and fiber contents varied significantly, according to proximate composition analysis, with U. lactuca (indoor) having the highest protein and carbohydrate content (p < 0.05). Biochemical indices indicates that indoor U. lactuca contained the maximum total chlorophyll, carotenoids, and fucoxanthin. Significant variations were found in the fatty acid analysis of the seaweed and oyster samples. The results showed that the outdoor oyster samples had more omega-3 fatty acids (p < 0.05) while the indoor seaweed samples had lower saturated fatty acids and higher polyunsaturated fatty acids. U. lactuca grown indoors exhibited the highest quantities of both essential and non-essential amino acids (NEAA). However, oyster samples did not significantly differ in their EAA content when grown indoors or outdoors, they did exhibit higher levels of NEAA in outdoors. The study emphasizes how culture circumstances affect the nutritional and biochemical profiles of seaweeds and oysters, and it offers indoor co-culture as a workable substitute for bad environmental conditions that yet allow for optimal growth and nutritional quality.