The effect of amphibious behavior on ion regulation in Periophthalmus cantonesis

• Main Authors: Chang, ill chi, 張詣奇
• Other Authors: Lin Hui-Chen
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/70114093890993526144

碩士 === 東海大學 === 生物學系 === 85 === The euryhaline and highly terrestrial fish, mudskipper (Periophthalmus cantonesis), lives in complex variable mangrove swamps or estuary mudflat habitata. Withinthesis habitats an array of environmental factors such as salinity fluctuations that occur both spatially and seasonal has various efects on the physiological adaptation of this species. The ion change in the environment is dramatic.Moreover P. cantonesis was completely out of contact with tide pool from the field observations. In order to understand the relationship between ambient ion variations and amphibious behavior of P. cantonesis, the effect of amphibiousbehavior on ion regulation in P. cantonesis was investigated in this study. P. cantonesis was first acclimated in 35 g/l SW and freemode and was subjected to two exercise modes (free mode and aquatic mode). Sodium ion concentrationand behavior performance of these fish were recorded. A series of three experiments was conducted in this study. In the long term salinity acclimation experiment(FW, 35 g/l SW, 60 g/l SW), there was no difference in plasma sodium ion concentration between exercise modes and among salinity treatments, and no difference in muscle sodium ion concentration between exercise modes was found. However, there was a difference in muscle sodium ion concentration among salinitytreatments. In the extreme salinity transfer experiment (FW -> 60 g/l SW), theextent of variations in plasma and muscle sodium ion concentrations in free modegroup was less than those in aquatic mode group (92 -116 % and 95 -191 % respectively). In free mode group, most P. cantonesis stayed in air, while some fish died in aquatic mode 2 hours after salinity transfer. In salinity simulationexperiment (35 g/l -> 0 g/l, 6 hr ->35 g/l, 6 hr), free mode group maintaineda constant plasma sodium ion cincentration (95 -108 %),wheres aquatic mode grouphad it changed with ambient salinity. Within the first 6 hrs, plasma sodium ionconcentration from the aquatic mode individuals dropped (74 -101 %), and then returned to their original levels (74 - 93 %) in the following 6 - 12 hrs. The behavior performance parameters (time of out of water, times out of water) did notchange after two salinity transfers. Salinity preference experiment was conducted.Regardless of the acclimated salinity, the mudskipper, in general, had a preferencefor 35 g/l SW among the three salinities provided (FW, 35 g/l SW, 60 g/l SW).In summary, amphibious behavior prevents the body ion concentration of P. cantonesisfrom changing with its ambient salinity in natural habitat. Finally, there werea lot of MR cells in both filaments and lamella in the gill of P. cantonesis.And the possible evolutionarysignificance of this observation was discussed.