三种造礁珊瑚对不同钙离子浓度的生理响应

Physiological responses of three hermatypic corals to different calcium ion concentrations

为了了解不同造礁珊瑚的生长对海水Ca^(2+)浓度变化的响应规律,本研究以浅杯排孔珊瑚(Seriatopora caliendrum)、丛生盔形珊瑚(Galaxea fascicularis)和指状蔷薇珊瑚(Montipora digitata)3种造礁珊瑚为对象,测定了它们在180、250、320、390、460和530 mg·L^(-1)6个Ca^(2+)浓度下的钙化率、最大光量子产量(Fv/Fm)和实际光量子产量(ΦPSⅡ)的变化。结果表明:低Ca^(2+)浓度(180 mg·L^(-1))导致3种珊瑚的钙化率均显著降低(P<0.05);随着Ca^(2+)浓度的增加,浅杯排孔珊瑚和指状蔷薇珊瑚的钙化率呈倒抛物线变化,即先上升后降低,并在320~390 mg·L^(-1)浓度时达到峰值;丛生盔形珊瑚钙化率在低Ca^(2+)浓度处理时(180~320 mg·L^(-1))随Ca^(2+)浓度上升而增加,而后趋于平稳;实验14天后,浅杯排孔珊瑚共生虫黄藻Fv/Fm和ΦPSⅡ随Ca^(2+)浓度的增加呈先上升后下降的变化趋势,过低或过高的Ca^(2+)浓度均会对浅杯排孔珊瑚的生理造成一定的胁迫;与第1天相比,实验处理14天后的丛生盔形珊瑚共生虫黄藻Fv/Fm不存在显著性差异,ΦPSⅡ显著上升;不同珊瑚对Ca^(2+)浓度变化的生理响应具有差异性,针对不同造礁珊瑚种类的室内人工繁育时,需密切关注养殖体系中Ca^(2+)浓度变化,并适时调整,以维持其最佳生长效率。

This study aimed to evaluate the effects of Ca^(2+)concentration on physiological response of three hermatypic corals,including Seriatopora caliendrum,Galaxea fascicularis and Montipora digitata.The calcification rate,maximum quantum yield(Fv/Fm),and effective quantum yield(ΦPSⅡ)were measured at six Ca^(2+)concentrations(180,250,320,390,460 and 530 mg·L^(-1)).The results showed that the calcification rate of three corals significantly reduced at low Ca^(2+)concentrations(180 mg·L^(-1)).With increasing Ca^(2+)concentration,the calcification rates of S.caliendrum and M.digitata displayed inverted parabolic growth and peaked at 320-390 mg·L^(-1),while the calcification rate of G.fascicularis increased with increasing Ca^(2+)concentration at low Ca^(2+)concentration(180-320 mg·L^(-1))and then did not change afterwards.Fourteen days after treatment initiation,the Fv/Fm andΦPSⅡof S.caliendrum-associated zooxanthellae showed a trend of first increasing and then decreasing with increasing Ca^(2+)concentration,probably because the corals suffered from a certain stress at too low or too high Ca^(2+)concentration.G.fascicularis-associated zooxanthellae displayed no significant difference in Fv/Fm but a significant increase inΦPSⅡat fourteen days after treatment initiation compared to that at day one of treatment initiation.These results indicate species-specific physiological response of corals to different Ca^(2+)concentrations.Therefore,it is necessary to pay attention to and adjust Ca^(2+)concentration in closed circulating aquacultural systems for hermatypic corals to maintain the optimum growth.