The clinging behaviour during high tides in the mudskipper, Periophthalmus cantonensis

• Main Authors: Shan-Hui Su, 蘇珊慧
• Other Authors: Hui-Chen Lin
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/11667482379078126947

碩士 === 東海大學 === 生物學系 === 87 === Abstract Most fishes are adapted to aquatic habitats, breathing by their gills, very few of them have the ability to breathe in air. Mudskippers are the most abundant air-breathing fishes in mangrove swamps and estuaries. It is a specialised group of Gobies characterised by having periscope like eyes and muscular limblike pectoral fins. They spend more time skipping across the mudflats than swimming in water. The highly terrestrial and euryhaline of mudskippers have been well studied with respect to adaptations to aquatic and aerial life. Only a few works have been done on the adaptive aspects of behaviours observed in nature. There are at least four species of mudskippers in Taiwan. Periophthalmus cantonensis is the most common of the four. In the field, when the tide rises, P. cantonensis clambers onto rocks with only its tail fin dipped into water, the other three species of mudskipper retreat into their water-filled muddy burrows and resurface only when the tide ebbs. This study aims to explore why P. cantonensis exhibits clinging behaviour during high tides and what factor is more important to the clinging behaviour in terms of non-biological and biological factors. First, I tried to find the correlation between environmnetal parameters and clinging behaviour. Environmental parameters were measured at 0.5 hour interval over 6 hours a day. Fish behaviour was videotaped, only the dissolved oxygen showed a significantly negative correlation with the time P. cantonensis spent in air. A 3×3 factorial design study was conducted in order to respectively evaluate the effect of dissolved oxygen and salinity on fish behaviour during low tides. A significant effect was observed not from the two main effects, but from the interaction of dissolved oxygen and salinity, indicating the complicate and variable characters of the microhabitat. Two studies were conducted in order to evaluate the effect of dissolved oxygen and salinity on the clinging behaviour during high tides. The results showed that neither dissolved oxygen nor salinity was the profound factor to clinging behaviour. And, finally, a study was conducted in order to test the effect of predation on clinging behaviour. The results showed that aquatic predation pressure significantly favors the exhibition of clinging behaviour. From the survey of environmental parameters, the average dissolved oxygen concentration during high tides is higher than the lowest lethal dissolved oxygen concentration. In addition, P. cantonensis showed no preference for any particular salinity, but would avoid exposure to lower salinity. Therefore, the environmental condition during high tides may not be stressful enough for P. cantonensis to escape from the water. This study suggested that predation risk seemed to be a stronger factor influencing the clinging behaviour in the mudskipper, Periophthalmus cantonensis.