Leukocyte Profiles and Phagocytic Response of the Nile Tilapia in Relation to Water Quality and Macrobenthic Indicators

This study investigated the relationship between water quality, macrobenthic composition, and innate immune responses in Nile tilapia (Oreochromis niloticus) cultivated in a tropical freshwater aquaculture system. Water samples and biological data were collected from six stations at the Sumberpasir Aquaculture Laboratory, Universitas Brawijaya. Physicochemical parameters measured included temperature, pH, ammonia, and total organic matter (TOM), while macrobenthic community structure was analyzed through diversity and dominance indices. Fish hematological assessments were conducted at two culture stations (Stations 1 and 2), where leukocyte differentials (lymphocytes, monocytes, neutrophils) and phagocytic activity were quantified. Canonical Correspondence Analysis (CCA) revealed that Baetidae were associated with high pH and stable temperatures, indicating clean water conditions, whereas Potamidae, Thiaridae, and Pachychilidae were linked to elevated ammonia and TOM, suggesting pollution tolerance. In tilapia, lymphocyte counts remained within physiological norms (69–71%) under favorable water conditions, while monocytes and neutrophils declined in response to increased pollution levels. Spearman correlation analysis demonstrated strong negative associations between ammonia and immune parameters, particularly neutrophils (r = –0.992) and phagocytosis (r = – 0.927). These findings highlight that macrobenthic bioindicators and fish leukocyte profiles are effective tools for detecting ecological stress and guiding sustainable management in aquaculture environment.