EFFECT OF TEMPERATURE AND SALINITY ON DEVELOPMENTAL STAGES OF MARINE GASTROPODA, Nassarius festivus  

Nassa mud snail Nassarius festivus is a small gastropod usually living on mud flats or sand flats, intertidal or subtidal and is on an important position of the tidal ecosystem in Korea. Although this species is not an important fisheries resources, it can be a good candidate organism with potential for various kinds of biological experiments. N. festivus is easy to collect and culture in laboratory owing to its high resistance to changes in environmental conditions. Especially, various life stages of this organism can be used in the experiments. At present, Republic of Korea has been actively searching for standard test organisms. In this study, we tried to find the optimum conditions for laboratory culture of N. festivus. Experiments were conducted to know the effects of water temperature and salinity on embryos and larva (veliger) stages of N. festivus.

Temperature affected significantly the hatching time. As temperature increased from 15 to 30℃, hatching time decreased. Within the temperature range of 5-10℃, exmbryo did not developed and finally died during the experiment. The hatching rate was 100% at 15-30℃. The larval survival was not affected by temperature. Survival of veliger under the temperature range 5-30℃ were above 88% after 96 hours. As for salinity, larvae could not survive in lower salinity less than 10 psu. They all died within 24 hours at 5 psu and 48 hours at 10 psu. However above 15 psu, larval survival exceeded 96%. The results of this study suggest N. festivus have a wide tolerance for the various range of temaperature and salinity.