Effect of carbonate alkalinity on embryonic development and larval vitality of Pramisgurnus dabryanus

To investigate the adaptation of the embryos and larvae of Paramisgurnus dabryanus to carbonate alkalinity, we cultured the embryos which had developed to the blastocyst stage in water at carbonate alkalinities of 0, 10, 20, 30 and 40 mmol·L⁻¹, so as to investigate the hatching period, hatching rate, abnormality rate, survival rate, specific growth rate (SGR), yolk sac absorption and survival activity index (SAI). The results show that: 1) The embryo hatching rate was highest at carbonate alkalinity of 10 mmol·L⁻¹ without significant difference compared with that of the control group (P>0.05). The hatching period was significantly shorter than that of the control group at carbonate alkalinities of 10 and 20 mmol·L⁻¹ (P<0.05). 2) The abnormality rate of the newly hatched larvae ascended gradually with the increase of carbonate alkalinity, while the survival rate of larvae of 3 dah (Days after hatching) gradually decreased. 3) The total length of newly hatched larvae decreased and then increased, while the total length of larvae of 3 dah increased and then decreased with the increase of carbonate alkalinity. The SGR and yolk sac absorption rate showed an increasing and then decreasing tendency. 4) The larval SAI first increased and then decreased with the increase of carbonate alkalinity and reached the maximum in 10 mmol·L⁻¹ group. It is indicated that the optimal carbonate alkalinity for the embryonic development and larval growth of P. dableanus is 0–10 mmol·L⁻¹.