Effects of Temperature and Salinity on Growth, Metabolism and Digestive Enzymes Synthesis of Goniopora columna

SIMPLE SUMMARY: Coral reefs are important habitats for marine life and have high commercial uses, which can be used in biomedicine, aquariums and tourism promotion. In recent years, climate change has posed a serious threat to coral survival. Therefore, it is very important to explore the effects of temperature and salinity changes on coral physiology. In addition to understanding the threat of climate change to corals, it can also be used as an important environmental indicator for coral large-scale aquaculture. This study aims to investigate the effects of different temperatures and salinity on the body composition, digestive enzymes and metabolism of G. columna, to explore the physiological and metabolic threats caused by climate change to G. columna, and to understand the most suitable temperature and salinity for G. columna growth. ABSTRACT: Climate change is causing dramatic changes in global ocean temperature and salinity, threatening coral survival. Coral growth and metabolism are greatly affected by the temperature, salinity and feeding time of the environment. In order to explore the threats to coral survival caused by climate change, this study will investigate the changes in body composition, digestive enzymes and metabolism of G. columna at different temperatures and salinities. A maximum G. columna growth rate was observed at 25 °C and 30–35 psu salinity. The G. columna could survive in a wide salinity range of 25–40 psu. However, the maximum number and weight of G. columna polyps was determined at 30–35 psu. Furthermore, 30–35 psu salinity at 25 °C led to the best G. columna growth and survival, mainly because of their enhanced nutrient absorption rate, polyp expansion rate, metabolic rate and adaptability. Comparing various salinity-temperature treatment groups, all obtained values for growth, behavior and metabolism were significantly higher (p < 0.05) for 30 psu at 25 °C than other treatment groups resulting in maximum G. columna yield. In addition, the optimal timing of G. columna feeding was assessed by studying changes in body composition and digestive enzymes within 24 h of feeding. The results showed that G. columna has higher protein and protease activity between 6:00 a.m. to 12:00 noon. Therefore, at 25 °C, 30–35 psu and feeding will enhance G. columna growth and survival.