## 4 Discussion  
This study showed that water temperature and diet were significant factors affecting the growth rate of _M. chinensis_ during the larval stage. As there have been no studies on the growth or survival of _M. chinensis_ larvae to date, the results of this study were compared to those of previous studies on _Meretix lusoria_[18]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Shell Length (\(\upmu\)m)**} & **Daily Increment** & \\  & **Initial** & **Final** & **of SL (\(\upmu\)m)** & **Survival (\%)** \\ \hline  & 25 & 76.1 \(\pm\) 2.1 & 162.4 \(\pm\) 8.75 \({}^{\text{b}}\) & 5.7 \(\pm\) 0.65 \({}^{\text{a}}\) & 45.5 \({}^{\text{a}}\) \\ Salinity & 30 & 76.1 \(\pm\) 2.1 & 231.6 \(\pm\) 10.63 \({}^{\text{d}}\) & 10.3 \(\pm\) 1.32 \({}^{\text{b}}\) & 75.5 \({}^{\text{d}}\) \\ (psu) & 35 & 76.1 \(\pm\) 2.1 & 224.3 \(\pm\) 9.28 \({}^{\text{c}}\) & 9.8 \(\pm\) 1.06 \({}^{\text{b}}\) & 70.4 \({}^{\text{c}}\) \\  & 40 & 76.1 \(\pm\) 2.1 & 145.9 \(\pm\) 6.65 \({}^{\text{a}}\) & 4.6 \(\pm\) 0.84 \({}^{\text{a}}\) & 52.5 \({}^{\text{b}}\) \\ \hline \hline \end{tabular} We intend a \(<\) b \(<\) c \(<\) d in shell length. Values in the same column with different superscript letters are significantly different (\(p<\) 0.05).  
\end{table} 
Table 2: The growth rate, daily increment of shell length SL and the survival rate of _Mactra chinensis_ reared at different salinities for 15 days. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**Shell Length (\(\upmu\)m)**} & **Daily Increment of** & \\  & **Initial** & **Final** & **SL (\(\upmu\)m)** & **Survival (\%)** \\ \hline _Isochrysis galbana_ & 80.6 \(\pm\) 2.3 & 234.1 \(\pm\) 10.6 \({}^{\text{cd}}\) & 10.2 \(\pm\) 0.85 \({}^{\text{d}}\) & 62.4 \({}^{\text{c}}\) \\ _Pavlova lutheri_ & 80.6 \(\pm\) 2.3 & 192.8 \(\pm\) 8.3 \({}^{\text{b}}\) & 7.4 \(\pm\) 0.51 \({}^{\text{b}}\) & 45.8 \({}^{\text{b}}\) \\ _Isochrysis_ sp. & 80.6 \(\pm\) 2.3 & 226.4 \(\pm\) 11.3 \({}^{\text{c}}\) & 9.7 \(\pm\) 0.66 \({}^{\text{c}}\) & 60.6 \({}^{\text{c}}\) \\ Mixture & 80.6 \(\pm\) 2.3 & 247.5 \(\pm\) 13.2 \({}^{\text{d}}\) & 11.1 \(\pm\) 1.10 \({}^{\text{d}}\) & 70.5 \({}^{\text{d}}\) \\ Not fed & 80.6 \(\pm\) 2.3 & 116.6 \(\pm\) 1.4 \({}^{\text{a}}\) & 2.4 \(\pm\) 0.15 \({}^{\text{a}}\) & 4.0 \({}^{\text{a}}\) \\ \hline \hline \end{tabular} We intend a \(<\) b \(<\) c \(<\) d in shell length. Values in the same column with different superscript letters are significantly different (\(p<\) 0.05).  
\end{table} 
Table 3: The growth rate, daily increment of shell length (SL), and the survival rate of _Mactra chinensis_ provided with a different microalgal supply for 15 days. Accumulating evidence suggests that a suitable water temperature range for the optimal growth of _M. lusoria_ larvae is 28-32 \({}^{\circ}\)C. In a previous study using the D-stage larvae of _M. lusoria_ with an initial SL of 109.5 \(\upmu\)m, the larvae grew to 209.0 \(\upmu\)m over 20 days when reared at 23-28 \({}^{\circ}\)C [19]. Another study showed growth in the SL of D-stage larvae of 112-209.0 \(\upmu\)m at a water temperature of 27 \({}^{\circ}\)C by day 20 of the experiment, whereas the daily growth rate was recorded to be 6.0 \(\upmu\)m [20]. In the present study, the SL of _M. chinensis_ larvae was 222.6 \(\pm\) 8.61 \(\upmu\)m at 22 \({}^{\circ}\)C on day 15 and gradually increased as the water temperature increased. However, at a water temperature above 27 \({}^{\circ}\)C, the survival rate dropped below 30%. Therefore, these findings indicate that the suitable range of water temperature to encourage the growth of _M. chinensis_ larvae is 17-27 \({}^{\circ}\)C, with an optimal temperature of 22 \({}^{\circ}\)C. Therefore, the optimal temperature for _M. chinensis_ growth is lower than that for _M. lusoria_ growth. These results demonstrate that the optimal water temperature for breeding varies in a species-specific manner. The _M.