Combined effect of temperature and salinity on the fertilization, hatching, larval development and expression of selected genes of major carp (Labeo rohita)

Temperature and salinity play a vital role in organismal physiological status including growth, immunity and survival. Any deviation from the optimum temperature and salinity level can adversely affect the aquaculture productivity because of imposed stress on organisms. The present study was conducted to assess the role of temperature and salinity on the fertilization, hatching and larval development of Labeo rohita under the combined effect of three different experimental temperatures (30°C, 33°C and 35°C) and two salinity levels (0‰, 2‰) for a period of 10 days. The experimental species reared at 2‰ and 35°C, showed significantly higher (p<0.05) relative expression pattern of two osmotic stress genes (NKA and HSP70) whereas the result also revealed lower expression levels of three growth and cell proliferation genes (MBL, SLB and IGF-1). The highest levels of physiological traits and gene expression changes were obtained at 2‰ and 35°C (T5) while the lowest levels of physiological-genetic changes were observed at 0‰ and 30°C (control treatment). Findings of this study demonstrate the adverse effect of temperatures and salinity stress on the fertilization, hatching, yolk sac absorption and larval development and gene expression pattern.