ABSTRACT
Aim: A study was designed to measure the solar UV- B in Uttarakhand, Garhwal region and to observe the effect of retene and psoralene photosensitizers on hill stream fishes, Tor tor and Garra gotyla in the presence of natural solar ultraviolet and equal intensity of artificial UV-B radiation.Methodology: Solar UV-B was measured with the help of Kipps and Zonen radiometer having UV-B sensors. Experimental sites selected were Dehradun and Tehri located in Garhwal region of Uttarakhand. The artificial radiation was provided with Philips UV-B Lamps. Mortality, biochemical and enzymological parameters, which included glutathione, glucose-6-phosphatase, catalase and lipid peroxidation were analyzed. Results: The data of monitoring of UV-B showed that the maximum UV-B intensity was observed during the month of May to August and the minimum was in the month of December to February. Mortality rate of fish exposed to solar radiation, artificial UV-B, psoralene and retene indicated highest with 26% in Tor tor, exposed with psoralene+ artificial UV-B. Reduced glutathione, glucose- 6- phosphatase and catalase level decreased in all the groups compared to control. The maximum reduction in GSH level was observed after treatment of artificial UV-B + psoralene in Tor tor, while maximum reduction in catalase and glucose-6- phosphatase was observed after retene and artificial UV-B. Interpretation: Tor tor and Garra gotyla are important hill stream fishes. Retene and psoralene are natural photosensitizers present in the aquatic ecosystem and become phototoxic by generating oxidative radicals. Artificial UV-B was more toxic than natural solar radiation and Tor tor was found more sensitive than Garra gotyla. Enhanced UV-B with retene and psoralene photosensitizers affect hill stream fishes and aquatic biodiversity.
ABSTRACT
A study was conducted on the economically important fishes Labeo rohita (Hamilton 1822), Tor tor (Hamilton 1822) and Labeo calbasu (Hamilton 1822) stocks from the Ken, the Paisuni and the Tons rivers in the Vindhyan region. Asymptotic length was maximum in L. rohita (946, 833 and 962 mm) as compared with T. tor (822, 787 and 946 mm) and minimum in L. calbasu (567, 612 and 692 mm) in the Ken, the Paisuni and the Tons rivers, respectively. The growth coefficient and total mortality was maximum in T. tor compared to L. rohita and minimum in L. calbasu. Fishing mortality was maximum in T. tor (2.9, 4.57 and 3.44) and minimum in L. calbasu (0.51, 1.21 and 1.18) while natural mortality was maximum in L. rohita (0.74, 0.94 and 1.86) and minimum in L. calbasu (0.47, 0.65 and 0.68). Natural mortality indicated that the habitat was more suitable for L. calbasu. Comparatively, fishing pressure was very high in T. tor than L. rohita and L. calbasu. Exploitation rate was maximum in T. tor (0.71, 0.82 and 0.84) compared to L. rohita (0.77, 0.74 and 0.56) and minimum in L. calbasu (0.52, 0.65 and 0.63) in the Ken, Paisuni and Tons rivers, respectively.