Descripition of early development in giant clam, tridacna maxima (roding, 1798) and the determination of physiological behaviour of adult as a response to temperature

Abstract

Population of giant clam has been decreasing severely in many regions due to harvesting and stress-induced bleaching. Mariculture studies have been directed to focus on artificial spawning induction, rearing of larvae and relationship of zooxanthellae to host nutrition. However, data for this purpose is specifically lacking in Malaysia especially for Tridacna maxima. This study was done to describe the artificial spawning induction events in broodstocks using Serotonin and the early life development from embryo to larvae morphologically. Furthennore, was to detennine the physiological behaviour of adults as a response to temperature in tenns of photosynthesis and respiration. Three trials were conducted using 1 ml of 2 mM serotonin honnone to induce spawning in four different broodstocks. Sperm were released after 1-2 min after injection and lasted for about 10 min while eggs released took place after about 13 min and lasts about 45- 75 min. After fertilization, the survival and growth of larvae collected were followed until pre-metamorphosis stage. Larval survival was 21.62 % at day 2 and 0.11 % at day 4. On day 6 whole batch of culture collapsed because of bacterial contamination. Size of unfertilized eggs was 102.78 ± 2.78 µm and reached larvae size of 145.56 ± 8.08 µm on day 6. Increase in total shell length and width length is more noticeable compared to hinge length. Morphological study was carried out using light compound microscope.