Integrated multi-trophic aquaculture (IMTA) of seaweed and shrimp, Litopenaeus vannamei, with partial reduction in feed rate for improved water quality and nutrient efficiency of the culture system

Abstract

Seaweed possesses an incredible ability to absorb excess nutrients (N and P) and serves as a natural food source for marine species, making it a valuable component in integrated aquaculture systems that promote sustainable farming practices. This study investigated the effectiveness of coculturing whiteleg shrimp (Litopeneaus vannamei) with either red seaweed (Gracilaria tenuistipitata) or green seaweed (Cladophora sp.) under partial feed rate decrease was evaluated for 60 days. Five treatments were implemented, each with three replicates: a control group of shrimps in monoculture receiving commercial feed at a 100% feeding rate; and four groups of shrimps cocultured with each seaweed species receiving 100% or 75% of the control treatment’s feed rate. Shrimp juveniles (0.35 ± 0.04 g) were raised at a density of 200 individuals/m³, salinity level of 15 ppt, and seaweed biomass rate of 2 kg/m³. Results indicated that in the polyculture system with a 75% feeding rate, levels of total ammonia nitrogen (TAN), nitrate (NO₃⁻), nitrite (NO₂⁻), and phosphate (PO₄³⁻) as well as counts of heterotrophic bacteria and Vibrio spp. were significantly reduced, indicating that a good culture medium was maintained. Shrimp growth, survival, and yield in polyculture with a 75% feeding rate were significantly higher and the feed conversion ratio was reduced by 36.24–39.28% compared to the control group. Notably, these performance metrics were superior in the G. tenuistipitata group compared to the Cladophora sp. group, suggesting that this red seaweed could be beneficial and more efficient for shrimp polyculture systems. Biochemical analysis of fresh shrimp meat in the coculture revealed that ash was increased and fat was decreased. However, moisture and protein were not significantly impacted compared to the monoculture group.