Effect of UV-B radiations on mortality and enzymes level in fish larvae of Tor tor and Schizothorax richardsonii on laboratory scale

Abstract

Depletion of stratospheric ozone layer is resulting into increase in solar UV-B on earth surface. Ultra violet radiation is well known to cause many detrimental effects in aquatic organisms. The present study was performed to study the effect of solar ultraviolet radiation on fish fingerlings of Tor tor and Schizothorax richardsonii as a model system on laboratory scale. The effect of different intensities of natural solar and artificial UV-B radiation on fish larvae of T. tor and S. richardsonii in a presence of retene was investigated. Solar ultraviolet intensity showed seasonal and altitudinal variations in Garhwal region. Solar UV radiation level was lower (0.390 mw/cm2) in the month of January- February at lower altitude and highest (1.192 mw/cm2) in the month of July-August 2018 at higher altitude. Fish larvae exposed to artificial UV-B (average wavelength 312 nm and intensity of 750 mw/cm2) with retene (50µg/l) showed increase in gills malandialdehyde level and caused larvae mortality as indicating that enhanced solar UV-B exposure could be lethal to fish fauna in aquatic ecosystem. Artificial UV-B had a stronger damaging effect on fish larvae than solar radiation exhibited highly toxic in presence of retene. The larvae of S. richardsonii was found more sensitive than T. tor as indicated by high mortality rate (30%) and high pigmented characteristics on dorsal side. The solar and ultraviolet radiation showed a positive effect on high pigmentation. These results suggest that on a short time scale, UV-B radiation causing developmental stress on fish larvae may contribute to assess the phototoxic behaviour of cold water fishes.

Evaluation of Oxidative Stress Enzymes of Spawn and Fry of Clarias batrachus (Linn. 1758) Exposed to Artificial UV-B Radiation: A Biomarker Analysis

“…The catalyse (CAT) activity of the spawn and fry of C. batrachus revealed decreased trend compared to the control, only at 10D5M the value increased slightly for both the spawn and fry, it may be possible that both of them intended to cope up with environmental condition. Similar results were found in another study, where catalase was decreased in case of fish fingerlings of Tor tor and Schizothorax richardsonii when treated with retene, solar UV radiation and artificial UV radiation (Kumar et al, 2019). Decreased CAT activity was also found in the different doses of 365 nm UV radiation in the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) larvae treated with UV radiation (Güven et al, 2015).…”

“…Decreased SOD activity leads to less defence properties and it finally leads to the oxidative damage, damage to DNA and generation of ROS, because superoxide dismutases are the main antioxidants of defence pathways in response to oxidative stress (Zhang et al, 2020). The significant reduction of SOD activity under the exposures of UV-B and solar radiation in fish larvae that acted as sole biomarker for reactive oxygen species which caused damage to lipids, protein and DNA was also explained (Kumar et al, 2019). Being an important endogenous antioxidant enzyme it acts as a component of first line of defence system against the reactive oxygen species (ROS) (Ighodaro and Akinloye, 2018).…”

Ecology and diversity of plant aphids in Garhwal region of Uttarakhand, India

“…The severe effects of UV-B radiation along with photosensitizer on larval development, mortality and offspring were studied (Kumar et al, 2019). Studies with adult have shown that UV-B radiation act as immuno suppressive agent to aphids.…”