Thermal Ecology of Two Fresh Water Fishes Aphanius dispar and Gambusia affinis from Central Saudi Arabia PDF

Keywords

ecology, Saudi Arabia, freshwater fish

Abstract

Temperature selection of two fresh water fishes Aphanius dispar (Ruppel 1828) and Gambusia affinis Holbrooki (Girard 1859) was investigated in a thermal gradient. One animal at a time was studied in three temperature gradients extending from 6 to 40°C (Low range 6-21°C; Medium range 13-31°C; High Range 21- 40°C). Most of A. dispar selected temperatures between 14-15°C in the low range, 19-22°C in the medium range and 26-32°C in the high range, while G. affinis selected temperatures between 13-20°C in the low range; 22-30°C in the medium range and 22-32°C in the high range. The mean critical thermal maximum (C.T. Max.) for A. dispar and G. affinis was 38.1°C and 38°C respectively. The mean critical thermal minimum (C.T. Min.) was 4.2°C and 4.4°C for A. dispar and G. affinis. Both species showed a tolerance to high temperature, but the introduced species, G. affinis had a wider range and is better suited to adopt to the desert habitat, and hence could constitute a thread to the endemic species A. dispar.