Studies on hill stream fish photosensitivity with psoralene and retene photosensitizers

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.