Abstract:
Sponge, Pachastrissa sp. (Demospongiae: Astrophorida: Calthropellidae) are known for their value in medicine. Distribution and growth of this sponge was monitored in Kong Hin Sam Pan Yuen, Sichang Island during June 2003 to June 2004. Reproduction biology was also observed both in field and histological study in the laboratory, sponge culture experiments were also conducted in the open system. The result on the natural distribution of this sponge revealed that it was a rare species, growing in clump with low percent coverage of 1.2 sq.cm. per sq.m. Several environmental factors were responsibled for the sponge growth in nature as revealed by the changes in percent coverage. Salinity, temperature and phytoplankton were the major parameters. Biological factors in particular the reproductive phases in sponge, competition and predation were also important. From this study, salinity, temperature, phytoplankton abundances (diatoms and bluegreen algae) were significantly correlated with the percent coverage in sponge. The reproduction pattern and time of spawning in sponge, Pachatrissa sp. reveal that the sponge was protogyrous hermaphroditism. Gametogenesis occurred once a year with the oogenesis followed by the spermatogenesis. This species was also viviparous. The oogenesis cycle started in January to July while the spermatogenesis occurred in April to July. Embryos were expected to be July. Larvae should be found in the water column from May to July. However in the study, the embryos were found during April to June. The larvae were not studied. Sponge culture experiments were conducted from January-December 2003 of the 32 sponge colonies, they were divided into those with biomass less than 80 grams and those with biomass more than 80 grams. Those with large biomass grew faster within 6 months. Another culture experiments conducted in 3 different conditions, namely tank C receiving water from the close system, tank D receiving water from the culture system and tank E as reservoir tank drawing in seawater from surrounding area. The net growth rate in the tank D, in the culture system, was highest. However the culture conditions in these experiments were not appropriated. The decrease growth rates were due to the low flow rate, the accumulation of wastes and the food shortage