Yun Kyung Shin

Physiological Changes and Energy Budget of the Sea Squirt Halocynthia roretzi from Tongyeong, South Coast of Korea

【The sea squirt Halocynthia roretzi is mainly cultured in Tongyeong, Southern coastal area of Korea. This study presents the physiological rates of respiration, excretion, feeding and assimilation efficiency of the sea squirt Halocynthia roretzi to analyze the SFG(scope for growth) and net growth efficiency, determined during 2007. Oxygen consumption and nitrogen excretion rates increased with a rise in temperature during the summer period whereas feeding rates decreased. The O:N ratio was high during winter(October to February). Assimilation efficiency showed an annual average of 75.4% during the experimental period, except during a period of elevated temperature in July to September(average

Starvation Effects on Occurrence of Tunic Softness Syndrome in Sea Squirt Halocynthia roretzi

25^{\circ}C

Classification and Ultrastructure of Hemocytes in the Tunicate Halocynthia roretzi (Ascidiacea: Pyuridae)

). Net growth efficiency(

Physiological Responses in Abalone Haliotis discus hannai with Different Salinity

K_2

Occurrence of bi-flagellated protists in the tunics of ascidians Halocynthia roretzi with tunic-softness syndrome collected from Tongyeong, south coast of Korea

) was 8.7 to 64.2% except for May to September, when temperature increased at the aquaculture farm. SFG was negative from May to September, reflecting high temperatures and low feeding rates during this period; its highest positive values occurred during winter.】

Seasonal Changes in Physiology of the abalone Haliotis discus hannai reared from Nohwa Island on the South Coast of Korea

We examined the effect of starvation on the occurrence of tunic softness to determine the cause of mass mortality of cultured Halocynthia roretzi (Drasche) in the Tongyeong region, Korea. In terms of the survival rate of H. roretzi and the occurrence rate of tunic softness, H. roretzi starved for 35 days at water temperatures of 8, 12, and (room temperature of ) did not exhibit tunic softness at water temperatures of either or . for morphological changes, although the tunic of H. roretzi was shrunken and became visibly smaller with a darkening color in all experimental groups, as compared to the state prior to starvation, its tunics bulbs continuously. The ratio of RNA/DNA concentrations and protein contents for each of the tunic sections were lower in the starved group. Our results indicate that tunic softness is not related to feeding deficiency, as no histopathological symptoms were apparent in the digestive gland or tunic of H. roretzi due to starvation.

Effect of Temperature and Dissolved Oxygen on the Survival Rate and Physiological Response of the Warty Sea Squirt Styela clava

The hemocytes of the tunicate Halocynthia roretzi are classified into six types based on their size, cellular form, and fine structure of the cytoplasmic granules: hyalinocytes, granulocytes, phagocytes, nephrocytes, morula cells, and multi-vacuole cells. Based on cell size, they are ordered multi-vacuole cells ()>nephrocytes ()>phagocytes ()>granulocytes ()>morula cells ()>hyalinocytes (). The proportion of hemocytes is ranked in the order multi-vacuole cells (54.8%)>nephrocytes (16.9%)>granulocytes (9.9%)>morula cells (8.8%)>phagocytes (6.1%)>hyalinocytes (3.5%).