Effects of Na+, K+ concentrations and Na+/K+ ratio on early development of Anguilla japonica

Abstract:

Impacts of different Na⁺ and K⁺ concentrations and Na⁺/K⁺ ratios on the hatching rate of fertilized eggs, deformity rate of newly hatched larvae and survival time of larvae of Anguilla japonica were studied in this paper. There were three experiments1) maintaining normal Na⁺ concentrations, while changing the concentration of K⁺; 2) maintaining normal K⁺ concentrations, while changing the concentration of Na⁺; and 3) maintaining stable Na⁺/K⁺ at 28, while changing both Na⁺ and K⁺ concentrations. The results showed thatWhen the concentration of K⁺ was 538 mg/L and Na⁺ 10760 mg/L, the highest hatching rate (44.0%) and the lowest deformity rate (23.8%) as well as the longest survival time were achieved. When Na⁺ to K⁺ ratio maintained at 28, with Na⁺ and K⁺ concentrations at 8400 mg/L and 300 mg/L respectively, the hatching rate was the highest among the five groups. Hatching rates would decline if the concentrations of Na⁺, K⁺ were too high (19500 mg/L and 1076 mg/L respectively). These results indicated that appropriate Na⁺, K⁺ concentrations and R values are required with optimum Na⁺, K⁺ concentrations varying between 7800-11700 mg/L and 360-540 mg/L respectively and R values 20-30.