Growth Response and Final Biomass of Amphipods Phronima sp. to Gradual Salinity Reduction in Controlled Culture System

Abstrak

Phronima sp. is a marine amphipod with potential as a natural feed in fisheries cultivation activities. One of the challenges in its development is its ability to adapt to salinity changes during the research process. This study aims to analyze the effect of salinity decrease frequency on the growth of Phronima sp. The research used an experimental design with four treatments: salinity reduction of 5 ppt every 3 days (P1), every 2 days (P2), daily (P3), and control without salinity reduction (P4). Phronima sp. was reared for 21 days in 20 L containers with a density of 10 individuals/L. Observed parameters included absolute weight growth, absolute length growth, Specific Growth Rate (SGR), population growth rate, and water quality parameters. Data were analyzed using ANOVA or Welch ANOVA at a 95% confidence level. The results showed that salinity reduction frequency had no significant effect (P>0.05) on all growth parameters of both broodstock and juvenile Phronima sp. However, the P2 treatment showed the highest average values for absolute weight growth, SGR, and population growth rate. Water quality during the study remained within suitable ranges for Phronima sp. growth, with temperature of 26.5–29.6°C, pH of 8.25–8.50, and dissolved oxygen of 5.52–6.68 mg/L. These findings indicate that gradual salinity reduction to 0 ppt with different frequencies remains within the physiological tolerance of Phronima sp. and does not significantly affect its growth.