본 연구에서는 강도다리의 담수순화방법으로 급격한 염분변화(AD)와 단계적인 염분변화(SD II과 III)를 주었을 때 강도다리의 생리적 반응을 조사하였다. AD에서 Ht, RBC 및 Hb는 Exp. II에 비해 증가하는 값이 높게 나왔으며 회복하는 속도도 느렸다. 그러나 SD II는 Ht, RBC 및 Hb에서 실험개시시수준과 실험종료시의 값이 유의한 차이를 보이지 않았다. AD에서 cortisol의 농도는 실험개시시 $2.1{pm}1.0{mu}g/mL$로부터 실험개시 후 6시간째에 $13.7{pm}0.2{mu}g/mL$ 급격히 증가하였으나 10일째에 $3.10{mu}g/mL$로 실험개시시 수준으로 회복되었다. SD I에서 cortisol의 농도는 실험개시시 $2.1{pm}1.0{mu}g/mL$로부터 6시간째에 $13.6{pm}0.6{mu}g/mL$로 증가하였고, 실험종료시인 10일째에 $3.1{pm}0.4{mu}g/mL$로 회복되었다. SD II에서 cortisol의 농도는 실험개시시 $2.1{pm}1.0{mu}g/mL$로부터 6시간째와 12시간째에 각각 $10.5{pm}2.5$, $10.8{pm}5.6{mu}g/mL$로 증가하는 경향을 보였으나 48시간째부터 실험개시시 수준으로 회복되는 경향을 보였다. 글루코스 농도는 AD, SD I과 II에서 cortisol의 경향과 다르게 유의한 차이를 나타내지 않았다. 삼투질농도는 실험개시시 $286.8{pm}3.3;mOsm/kg$으로 나타났으며, AD와 단계적 염분변화 실험구인 SD I, II에서는 실험종료 시에 각각 $266.3{pm}8.5$, $242.0{pm}12.5$, $269.5{pm}4.9;mOsm/kg$으로 유의하게 감소하는 경향을 보였다. 혈장의 $Na^+$, $K^+$ 및 $Cl^-$ 농도는 AD의 경우, $Cl^-$(mEq/L)만이 실험개시시의 수준과 유의한 변화를 볼 수 없었고, $Na^+$(mEq/L)와 $K^+$(mEq/L)는 유의하게 감소하는 경향을 보였다. SD I에서도 $Cl^-$(mEq/L)만이 실험개시시의 수준과 유의한 변화를 볼 수 없었고, $Na^+$(mEq/L)와 $K^+$(mEq/L)는 유의하게 감소하는 경향을 보였다.
Physiological responses (hematological factors, cortisol, glucose, osmolality, $Na^+$, $K^+$ and $Cl^-$) in starry flounder Platichthys stellatus were investigated during freshwater acclimation in the conditions of different speeds in salinity change with acute-decrease (AD) or stepwise-decrease (SD I and II). In AD of acute-decrease salinity, hematocrit (Ht), red blood cell (RBC) and hemoglobin (Hb) were rapidly increased more than SD I of stepwise-decrease salinity. But in case of SD II, Ht, RBC and Hb were no significant difference from beginning to end of this experiments. In AD, cortisol level significantly increased from $2.1{pm}1.0{mu}g/mL$ at the beginning to $13.7{pm}0.2{mu}g/mL$ at 6 hours and recovered to the basal levels ($3.1{mu}g/mL$) at 10 days. In SD I, cortisol level was significantly increased from $2.1{pm}1.0{mu}g/mL$ at the beginning to $13.6{pm}0.6{mu}g/mL$ at 6 hours and recovered to the basal levels ($3.1{pm}0.4{mu}g/mL$) at 10 days. In SD II, cortisol level was a little increased from $2.1{pm}1.0{mu}g/mL$ at the beginning to $10.5{pm}2.5$, $10.8{pm}5.6{mu}g/mL$ at 6, 12 hours and recovered to the basal level at 48 hours. Glucose level of AD, SD I, II were no significant difference from beginning to end of this experiments. Osmolality was $286.8{pm}3.3;mOsm/kg$ at the beginning. In SD II of stepwise-decrease, osmolality was no significant difference during rearing in freshwater (FW). But AD of stepwise-decrease and SD I of stepwise-decrease, osmolality was a little decreased end of this experiments. In AD of acute-decrease, only $Cl^-$ level was showed no significant difference from beginning to end of experiment and $Na^+$, $K^+$ levels were decreased. In case of SD I, $Cl^-$ level was showed no significant difference from beginning to end of experiment and $Na^+$, $K^+$ levels were decreased.
