Effect of water temperature on haemocyte responses in the disk abalone Haliotis discus hannai Ino, 1953

Abstract

Effects of gradual water temperature modulations on neutral red retention time (NRR time) of lysosomes in haemocytes and haemocyte counts were studied in the disk abalone Haliotis discus hannai Ino, 1953. Experimental animals were acclimated at 18ºC for a period of one week before exposing to gradual water temperature modulations. After acclimation, the water temperature was gradually increased/decreased @ 1ºC every other day until the target temperature of 10ºC/26ºC was reached. The temperatures were maintained for seven days before being brought back to 18ºC from 10ºC/26ºC (@ 1ºC per day). Haemolymph samples were collected 48 h after each temperature change. The haemocyte density at 26ºC was significantly higher (p<0.05) than that at 18ºC and 10oC, and the lowest haemocyte density was obtained at 10oC. The NRR time of the abalone held at 26ºC, 18ºC and 10ºC were 31.6±1.1min, 84.6± 2.7 min and 41.3±1.7 min, respectively. The temperature changes between17ºC and 20ºC did not significantly affect the NRR time suggesting that this is the optimal water temperature range for maintaining lysosomal membrane integrity in this species.