Physical and chemical factors of water effects on the ctenophore Pleurobrachia sp. abundance in Doragh and Ghazaleh creeks in Khozestan province

Pleurobrachia sp. abundance in Doragh and Ghazaleh estuaries were studied during July 2005 to June 2006. The effect of temperature, salinity, turbidity, BOD5, NO3, NO2, PO4, hardness and pH as physical and chemical factors of water were investigated. Pleurobrachia sp. was the only species observed in this study. The lowest mean densities of the ctenophora were obtained in April (0/6 No/m3± 0/5) in Doragh creek and the high mean densities were obtained in November (2846/7 No/m3± 0/4) in Ghazaleh creek. The maximum and minimum mean salinity values at the Doragh creek were 47g/lit and 37g/lit being obtained in July and November and December respectively. The maximum and minimum mean temprature values at the Doragh creek were 32c˚ and 13c˚ being obtained in May and November respectively. The maximum and minimum mean temprature values at the Ghazaleh creek were 32c˚ and 15c˚ being obtained in May and November respectively. The result indicated that Pleurobrachia sp. density in Doragh estuary was negatively correlated with salinity (P<0/01, r=-0/59) and temperature (P<0/05, r=-0/79) and its abundance in Ghazaleh estuary was negatively correlated with temperature (P<0/05, r=-0/43).