ROUTINE METABOLISM OF MOSQUITOFISH (GAMBUSIA AFFINIS) AT THREE DIFFERENT SALINITIES

摘要

This study examined the influence of environmental salinity, ranging from near 0 ppt (freshwater) to 20 ppt, on routine metabolism of adult female mosquitofish at 20℃. Routine metabolic rate (RMR) averaged 0.19, 0.14 and 0.17 mgO_2 g~(-1) h~(-1) at 0, 10 and 20 ppt salinity, respectively. Limiting oxygen concentration (LOC) averaged 1.36, 0.93 and 1.12 mgO_2 l~(-1) at 0, 10 and 20 ppt salinity, respectively. Both RMR and LOC at 10 ppt were significantly lower than at 0 ppt, but neither was significantly lower at 10 ppt than at 20 ppt. Marginal metabolic scope (MMS = (RMR/LOC) * 1 mgO_2 l~(-1)) was 0.14, 0.15 and 0.15 mgO_2 g~(-1) h~(-1) at 0, 10 and 20 ppt salinity, respectively. These slight differences in MMS among salinities were not significant, suggesting that the adult female mosquitofish's metabolic capacity varies little over the salinity interval 0 to 20 ppt.