Microbial-mediated Relationship between Water Quality and Oxidative Stress in Whiteleg Shrimp Cultured in the Biofloc Technology System

Evellin Dewi Lusiana (Department of Statistics, Faculty of Mathematics and Natural Science, Universitas Brawijaya, Malang, Indonesia)
Mohammad Mahmudi (Department of Aquatic Resources Management, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Malang, Indonesia)
Asus Maizar Suryanto Hertika (Department of Aquatic Resources Management, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Malang, Indonesia)
Muhammad Musa (Department of Aquatic Resources Management, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Malang, Indonesia)
Sunadji Sunadji (Department of Aquaculture, Universitas Nusa Cendana, Kupang, Indonesia)
Alfina Pagita Larasati (Department of Aquatic Resources Management, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Malang, Indonesia)

Journal of Fisheries & Marine
2026: IN PRESS ISSUE (JUST ACCEPTED MANUSCRIPT, 2026)

Graphical Abstract Highlight Research 1. Physicochemical water quality parameters, particularly transparency, pH, and nitrite, exerted stronger direct effects on superoxide dismutase (SOD) activity in whiteleg shrimp (Penaeus vannamei) than indirect effects mediated through microbial community in the biofloc technology (BFT) system. 2. The phytoplankton community in the BFT ponds was consistently dominated by Bacillariophyceae across the entire 90-day culture period, while total bacterial abundance peaked at day 60 and declined at day 90, indicating temporal succession and maturation of the microbial community. 3. SOD activity increased progressively from DOC 30 to DOC 90, reflecting an enhanced antioxidant defense response in shrimp as cumulative environmental stress intensified throughout the culture cycle. 4. Path analysis integrated with principal component analysis (PCA) revealed that microbial community (total bacteria and phytoplankton) provided only weak direct and indirect mediation of oxidative stress response, suggesting that maintaining physicochemical water quality stability is the primary strategy for reducing oxidative stress response in BFT-based shrimp culture.   Abstract Biofloc technology (BFT) is increasingly used in intensive whiteleg shrimp (Penaeus vannamei) aquaculture to improve water quality, shrimp health, and system sustainability by promoting microbial biomass. However, the complex interactions among water quality, microbial community, and oxidative stress responses that reflect shrimp health remain poorly understood. This research aims to evaluate the relationships between water quality dynamics and oxidative stress responses in whiteleg shrimp, while accounting for the microbial community present in the BFT system. An observational (non-experimental) field study was conducted in three biofloc ponds (2 m diameter; 500 shrimp m⁻²) in Probolinggo, Indonesia, over a 110-day culture cycle. Principal component analysis (PCA) reduced the dimensionality of water quality variables, followed by path analysis of their direct and indirect effects on SOD mediated by the microbial community. Transparency, pH, and nitrite deviated from the recommended ranges, indicating suboptimal rearing conditions that act as potential stressors. Bacillariophyceae consistently dominated the phytoplankton community, total bacterial abundance peaked at day 60 and declined at day 90, and SOD activity increased steadily. Path analysis showed that water quality influenced SOD more strongly through direct than microbially mediated pathways. Physicochemical water quality is the principal driver of the oxidative stress response in BFT-based shrimp culture, whereas the microbial community exerts weak direct and indirect effects. The community may modulate antioxidant capacity, but it did not fully buffer shrimp against physicochemical stress. Future research should include additional biomarkers, such as catalase and malondialdehyde, for a more comprehensive evaluation of shrimp health.