Effects of long-term saline-alkaline stress on growth and ovary development of Exopalaemon carinicauda

In order to investigate the effects of carbonate alkalinity (CA) on the growth and ovary development of the ridgetail white prawn Exopalaemon carinicauda, three CA gradients of 3 mmol/L (control group), 5 mmol/L and 8 mmol/L were set to culture E. carinicauda for 60 days, and the effects of different CA stress on the growth performance, tissue structure, enzyme activity and ovary development were compared. The results showed that there was no significant difference in growth gain, weight gain or survival rate between 5 mmol/L and control groups (P>0.05), while those of 8 mmol/L group was significantly lower than control group (P<0.05). Hepatopancreas sections showed that the morphological structure of the lumen was severely deformed in 8 mmol/L group. Gill sections showed that gill filaments were swollen, blood cells swelled, epithelial cells were seriously damaged, and the stratum corneum space was deformed in 8 mmol/L group. Carbonic anhydrase activity in 5 mmol/L group was significantly higher than control group (P<0.05), while Na⁺/K⁺-ATPase activity in muscle showed no significant difference (P>0.05); there was no significant difference in carbonic anhydrase in hepatopancreas (P>0.05), and Na⁺/K⁺-ATPase activity in hepatopancreas of 8 mmol/l group was significantly lower than other groups (P<0.05). Na⁺/K⁺-ATPase activity in gill of two stress groups was significantly higher than control group (P<0.05). Ovaries of all three groups were able to develop, while only 3 mmol/l and 5 mmol/L groups had E. carinicauda ovary developed to stage Ⅲ; ovary sections showed that the arrangement of oocytes in 8 mmol/L group was loose, and the arrangement of surrounding follicular cells was loose and the number was small. To sum up, E. carinicauda can grow and develop in CA less than 8 mmol/L, but high CA may cause damage to the gills and hepatopancreas, thus affecting growth. At the same time, it is speculated that high CA may also affect the development rate of ovaries. This study provides basic data and reference information for the enhancement and cultivation of white shrimps in saline-alkaline water.