Coculture of the Pacific white shrimp Litopenaeus vannamei and the macroalga Ulva linza enhances their growth rates and functional properties

Abstract

Integrated multi-trophic aquaculture (IMTA) has been proposed as a potential solution to supply aquatic food in an environmentally friendly way. However, little is known regarding the impacts of IMTA on the growth rates and food quality of both animals and plants, as well as the seasonal effects. In this study, we conducted field mesocosm experiments using monoculture and coculture systems with the shrimp Litopenaeus vannamei and the macroalga Ulva linza for four weeks in different seasons (autumn, spring and summer) to address the research gap. To evaluate the environmental pollution caused by shrimp culture, there was no water exchange for culture systems including shrimps. Compared to monoculture of L. vannamei, coculture with U. linza significantly reduced dissolved inorganic nitrogen (DIN, 98.5–99.0%) and dissolved inorganic phosphorus (DIP, 98.2–98.8%) but enhanced dissolved oxygen (DO, 56.2–68.7%) and pH (10.7–18.6%) by the end of culture. Compared to monoculture, coculture stimulated the growth rates of L. vannamei by 38.1–58.8% and U. linza by 241.9–290.4% in all seasons, and increased the lipid content of L. vannamei by 24.2% in autumn and by 37.9% in summer and the contents of protein and ash of U. linza by 23.8–29.0% and by 27.6–68.6%, respectively, in all seasons. Coculture enhanced the content of most amino acids in U. linza and the content of total fatty acids (FA) and polyunsaturated fatty acids in L. vannamei in all seasons in comparison with monoculture. In addition, coculture lifted swelling capacity by 28.9–40.5%, water holding capacity by 39.8–43.3% and oil holding capacity by 31.4–32.4% for U. linza in autumn and summer. Apart from relieving eutrophication, deoxygenation and acidification, IMTA increased growth rates of both shrimp and Ulva and improved functional properties of U. linza, suggesting a green and productive aquaculture mode.