EFFECTS OF TEMPERATURE AND AMMONIA ON GROWTH, SURVIVAL RATE, RESPIRATORY RATE AND DEFORMITY RATE OF JUVENILE RED DRUM (Sciaenops ocellatus)

Abstract

This study aimed to evaluate the individual and combined effects of temperature (27 - 28°C, 30°C, 32°C) and un-ionized ammonia concentrations (NH₃: 0; 0.02; 0.03; 0.19; 0.23; 0.31 ppm) on the quality indicators of juvenile red drum (Sciaenops ocellatus). Fish were monitored for survival rate, growth (length, weight, specific growth rate - SGR), respiration rate, skeletal deformities, and recovery ability after exposure. Results showed that survival dropped from 90.0 ± 11.55% (27 - 28°C, 0 ppm) to 50.0 ± 11.55% (32°C, 0.31 ppm). Final length decreased from 43.00 ± 3.00 mm to 36.00 ± 0.01 mm (a 16.3% reduction), and weight declined from 0.82 ± 0.02 g to 0.47 ± 0.01 g (a 42.7% reduction). Respiration rate increased from 109.00 ± 1.73 to 157.33 ± 5.13 breaths/min, equivalent to a 44.32% increase. SGR based on weight dropped significantly from 4.82 ± 0.18%/day to 0.24 ± 0.19%/day (a 95.0% decrease). No visible skeletal deformities were observed across treatments. However, fish exposed to temperatures ≥ 30°C and NH₃ concentrations ≥ 0.19 ppm did not survive the recovery phase. The study identifies optimal nursery conditions as 27 - 30°C with NH₃ levels below 0.03 ppm. These findings provide a scientific foundation for refining hatchery protocols and improving environmental management strategies under climate change conditions.