Temperature and Salinity Tolerance of the Manila Clam, Ruditapes philippinarum

바지락 (Ruditapes philippinarum)의 온도 및 염분 내성

Tolerance on temperature and salinity of Ruditapes philippinarum was investigated in five different salinity, $32.0,\;25.6,\;19.20,\;12.80,\;6.40,\;3.20{\%_{\circ}}$ with increasing continuously $1^{\circ}C/day 2^{\circ}C/day\;and\;3^{\circ}C/day$ water temperature. R. philippinarum was acclimated to $18^{\circ}C\;and 25^{\circ}C$ before the experiment. Oxygen consumption rates and filtration rates of R. philippinarum were estimated during the experiment. $LT_{50}$ of two stocks acclimated to $18^{\circ}C\;and\;25^{\circ}C$ were similar. However, the maximum tolerance temperature of a stock acclimated $18^{\circ}C\;was\;36^{\circ}C$ while a stock acclimated $25^{\circ}C\;was\;37^{\circ}C$. This suggested that the higher water temperature a stock acclimated, the higher tolerance a stock showed, The surival rates of R. philippina겨m with the changes in salinities decreased below $19,2\;{\%_{\circ}}\;at\;18^{\circ}C\;and\;25^{\circ}C$. Oxygen consumption rates in the experimental group acclimated at $18^{\circ}C$ reduced with decreasing of salinity concentrations, while those of the experimental group acclimated at $25^{\circ}C$ showed irregular trend. Filtration rates revealed the maximum at 24{\~}28^{\circ}C$ in the experimental group acclimated ai $18^{\circ}C\;and\;31{\~}33^{\circ}C\;in\;those\;at\;25{\circ}C$. Filtraton rates shanty decreased at the lower salinity concentrations.

전북 곰소만에 서식하는 바지락, Ruditapes philippinarum을 대상으로 $18{\circ}C$와 $25{\circ}C$에 순응시킨 후 수온상승 ($1{\circ}C/day, 2{\circ}C/day$ 및 $3{\circ}C/day$) 및 염분 ($32.0, 25.6, 19.2, 12.8, 6.40$ 및 $3.20{\%_{\circ}}$) 변화에 따른 생존율, 여수율 및 산소소비율 둥을 조사하였다. $18{\circ}C$와 $25^{\circ}C$에 순응시킨 바지락의 반수치사온도 (LT-(50))는 두 순응온도구간에 차이를 나타내지 않았으나, 최대 임계온도는 $18^{\circ}C$에 순응시킨 실험구는 $36^{\circ}C$, 그리고 $25^{\circ}C$에 순응시킨 실험구는 $37^{\circ}C$로 고수온에 순응시킨 실험구에서 높았다. 염분변화에 따른 바지락의 생존율은 $19.2{\%_{\circ}}$이하에서 감소하였다. 산소소비율은 $18^{\circ}C$에 순응시킨 바지락의 경우, 염분감소에 따라 감소한 반면 $25^{\circ}C$에 순응시킨 실험구에서는 산소소비율이 불규칙하였다. 한편, 수온증가에 따른 여수율은 $18{\circ}C$에 순응시킨 실험구의 경우 $24^{\circ}C{\~}28^{\circ}C에서$, $25{\circ}C$에 순응시킨 실험구의 경우는 $31{\~}33^{\circ}C$에서 최대를 보인 후 감소하였으며, 염분변화에 따른 여수율은 염분감소에 따라 감소하는 경향을 나타내었다.