The Effect of Temperature on Goniastrea aspera Polyp Degradation and the Post-bleaching Resistance

Abstract

Coral recovery from bleaching depends not only on the intensity and continuity of some influencing factorsbut also on the cellular condition of the coral itself. The relationship between coral recovery and bleachingcan be studied from the loss process of zooxanthellae from a polyp and the tissue profile changes. Thisresearch focused on the degradation of polyp tissue due to temperature stressors and the potential recoveryafter bleaching in artificial media. It was conducted at Coastal Eco-development Laboratory of FPIK-UNDIPJepara and natural waters of coral reef ecosystem in Southern of Panjang Island Jeparafrom April toSeptember 2021. Four levels of temperature: 40oC, 36oC, 32 oC 28 oC were used to expose the sample organisms.The objectives of this research are, therefore, to (a)investigate the effect of temperature on the zooxanthellaedensity in the polyp tissues, (b) investigate the effect of temperature on process change of polyp tissues and(c) analyze the survivability of coral after bleaching. The results show that: (a) the optimum temperatureand exposure that zooxanthellae can resist in the polyp histology of Goniastrea aspera is 36 oC for 6 hours, (b)Higher temperature and longer incubation time degrade the tissue of the Goniastrea asperapolyp, influencethe zooxanthellae release and cause coral death, (c) The recovery of the Goniastrea aspera still occurs afterpartial bleaching and (d) Coral recovery is characterized by the zooxanthellae regulation process in thepolyp tissues and reaches perfect condition and to achieve perfect arrangement after week 12.