Sargassum fusiforme improves the growth conditions of prawn by means of nutrient utilization and improvement of the microbial environment

Abstract

The enrichment of inorganic nitrogen in the aquaculture water can contribute to aquatilia diseases and lead to seawater pollution. In this study, we explored the alleviating effect and mechanism of Sargassum fusiforme on ammonia poisoning in seawater during shrimp farming. The results revealed that in the early cultivation period, there was a 88.14 % elimination of NH₄⁺-N, an inhibition of the exponential proliferation of microalgae. However, after 10 days of cultivation, there were increases in the richness and diversity of the bacterial communities in the water. Although there were initial increases in the photosynthesis of S. fusiforme, along with significant increases in the contents of soluble proteins and the activity of antioxidant enzymes, there were corresponding reductions in the nitrogen absorption capacity and relative growth rate. During the later stage of cultivation, P. vannamei was subjected to NH₄⁺-N stress, which promoted the activities of antioxidant and immune-related enzymes; however, the period during which P. vannamei was subjected to NH₄⁺-N stress was short, and the RGR of P. vannamei was 1.35 %, which was significantly higher than other aquaculture systems. This indicated that S. fusiforme can efficiently utilize ammonia, improve the growth environment of P. vannamei, and enhance its survival capacity by optimizing the microbial community relationship in the water. These findings provided reference and data support for the construction of high-density breeding and the ecological treatment of aquaculture wastewater for aquatic animals.