Abstract
Salinity intrusion in coastal areas due to climate change is alarming. In this study, the effects of salinity on embryonic and larval development of striped catfish (Pangasianodon hypophthalmus) were studied experimentally. Embryos and larvae were exposed to seven salinity treatments (0, 2, 4, 6, 8, 10, and 12 ppt), each with three replications. Considerable survivability of embryos was recorded up to 6 ppt salinity. Mortality of embryos significantly increased at 8 and 10 ppt salinity, and 100% mortality was displayed within 12 h of exposure at 12 ppt salinity. The rate of hatching was significantly reduced at 8 and 10 ppt salinity. The 24 h lethal concentration (LC50) value of salinity for embryo was 11.24 ppt. Different types of deformities, such as undeveloped yolk sac, elongated gastrula yolk sac, and yolk sac bud, were highest at 10 ppt salinity. Similar to the embryo, considerable survivability of larvae was recorded up to 6 ppt salinity, and 100% mortalities were found within 24 h of exposure at 12 ppt salinity. The 24 and 48 h LC50 values of salinity for larvae were 10.63 and 8.48 ppt, respectively. Several types of deformities, including yolk sac ulceration, spine scoliosis, tail bent, yolk sac edema, and compromised swim bladder inflation, were highest at 10 ppt salinity after 48 h of exposure. Within 24 h of exposure, about 80% yolk sac of the larvae was absorbed at 8 and 10 ppt salinity, while 30%–50% yolk sac was absorbed at 0–6 ppt salinity. Growth rates in terms of length and weight were higher at 0, 2, and 4 ppt salinity and moderate at 6 and 8 ppt salinity. Overall, the current findings define the limits to optimize hatchery procedures for the culture of this species in low saline brackish water.
Highlights
Climate changes induced salinity intrusions in the coastal areas are cause for serious concern in tropical and subtropical countries (Rabbani et al, 2013)
Over the last four decades, the water salinity level increased about 26% in the coastal areas of Bangladesh (Alam et al, 2017). This salinity intrusion significantly affected the fertility of coastal areas that act as a barrier in sustainable agriculture that contributes to food security (Islam et al, 2005)
All analyzed data were exhibited as mean ± standard deviation (SD)
Summary
Climate changes induced salinity intrusions in the coastal areas are cause for serious concern in tropical and subtropical countries (Rabbani et al, 2013). Over the last four decades, the water salinity level increased about 26% in the coastal areas of Bangladesh (Alam et al, 2017). This salinity intrusion significantly affected the fertility of coastal areas that act as a barrier in sustainable agriculture that contributes to food security (Islam et al, 2005). An increase in water salinity changed the physicochemical parameters of the aquatic environments, which affected the aquatic flora and fauna (Ahmed, 2013). In this case, efficient management of brackish water. It may be necessary to revise the culture practices of salineintolerant species as well as to find innovative techniques for other existing species
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