In this study, we determined changes of ionic ratios and its effect on sperm characteristics during spawning migration in the Caspian roach.
The fish were divided into 3 treatment groups in terms of ionic ratios obtained during sampling (February, March and April) for each period of sampling.
A one-way analysis of variance (ANOVA) was carried out to determine variation in ionic ratios ([Na.sup.+] to [K.sup.+], [Na.sup.+] to [Ca.sup.+2], [Na.sup.+] to [Mg.sup.+2], [K.sup.+] to [Ca.sup.+2], [K.sup.+] to [Mg.sup.+2]and [Ca.sup.+2] to [Mg.sup.+2]).
The ionic ratios of the seminal plasma are presented in Table 1.
Table 1: Changes in ionic ratios of the seminal plasma of Caspian roach during the reproductive season.
Mean data for major ionic ratios are listed in Table 5.
Comparison of ionic ratios within rainfall to that of local seawater is a common practice (Hutton and Leslie 1958; Probert 1976; Blackburn and McLeod 1983) using the principle that the atmospheric moisture has been derived from evaporation of the ocean water.
Ionic ratios of seawater and other Queensland sites (m.e./L basis) Site DTC Na : Cl Na : Ca (km) Generic seawater (A) 0 0.86 22.73 Bribie Island seawater (B) 0 0.85 22.32 Whian Whian (C) 255 1.3 2.8 Cooloola (C) 0 0.83 16.0 Mundubbera (C) 157 1.2 2.2 Townsville (D) 0 0.68 1.8 Lansdown (D) 40 0.66 2.6 Site Na : Mg Na : K Na : S[O.sub.4] Generic seawater (A) 4.43 45.89 8.29 Bribie Island seawater (B) 4.22 44.85 7.88 Whian Whian (C) 6.0 10.0 N/A Cooloola (C) 4.1 43.7 N/A Mundubbera (C) 3.8 3.4 N/A Townsville (D) 3.2 15.0 N/A Lansdown (D) 3.2 12.0 N/A Site Cl : K : Cl S[O.sub.4] Generic seawater (A) 9.65 0.02 Bribie Island seawater (B) 9.28 0.02 Whian Whian (C) N/A N/A Cooloola (C) 9.8 N/A Mundubbera (C) 1.7 N/A Townsville (D) 3.8 N/A Lansdown (D) 2.3 N/A N/A, Not available.