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珊瑚礁生态系统拥有较高的初级生产力和生物多样性,为人类提供了极具价值的生态服务功能,比如丰富的渔业和旅游资源[1-2]。作为珊瑚礁生态系统的主要框架生物,造礁石珊瑚的生长得益于共生虫黄藻提供的光合作用产物,其能满足珊瑚的大部分能量需求。作为交换,造礁石珊瑚能为共生虫黄藻提供光合作用所需的二氧化碳(CO2)、无机营养和稳定的环境。但是,近年来表层海水升温和海洋环境污染威胁着造礁石珊瑚与虫黄藻的共生关系,共生关系的破裂将进一步导致珊瑚白化或死亡,珊瑚礁生态系统呈不断退化趋势[3-5]。随着人类对海岸带的开发日益加剧,海水悬浮物(Suspended solid)已经成为近岸珊瑚礁生态系统的主要胁迫因子之一。大量陆源颗粒物质随地表径流输入珊瑚礁区,造成海水悬浮物浓度显著升高,同时水体浊度也明显增加。海水悬浮物会产生遮蔽效应,降低共生虫黄藻的光合效率[6-7]。悬浮物还会缓慢释放出氮、磷等营养物质,促进水体中其他藻类的爆发生长,进一步加剧该遮蔽效应。海水悬浮物浓度的升高能对造礁石珊瑚的生存产生诸多消极影响,从而不利于珊瑚礁生态系统的稳定性,但相关了解仍然十分有限。
本研究于2020年5−9月期间调查了3个礁区(崖州湾、凤凰岛和西岛)的海水悬浮物质量浓度,并测定了礁区中普哥滨珊瑚(Porites pukoensis)的共生虫黄藻密度、叶绿素a+c2含量,以及共生双方的超氧化物歧化酶(Superoxide dismutase,SOD)、过氧化氢酶(Catalase,CAT)、谷胱甘肽S-转移酶(Glutathione S-transferase,GST)、一氧化氮合酶(Nitric oxide synthase,NOS)和酚氧化物酶(Phenoloxidase,PO)的活力,进而分析礁区悬浮物质量浓度差异对普哥滨珊瑚生理活性的影响,以期揭示造礁石珊瑚对高浓度悬浮物的的生理适应机制。此外,本研究还挑选了敏感生物标志物构建综合评价指标,旨在用以评估悬浮物对普哥滨珊瑚的影响程度。
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2020年5−9月,崖州湾礁区的海水悬浮物月平均质量浓度为13.7~19.4 mg·L−1,总平均质量浓度为16.3 mg·L−1;凤凰岛礁区的海水悬浮物月平均质量浓度为1.9~8.8 mg·L−1,总平均质量浓度为5.3 mg·L−1;西岛礁区的海水悬浮物质量浓度最低,月平均质量浓度为0.7~5.3 mg·L−1,总平均质量浓度为2.6 mg·L−1。双因素方差分析结果显示,崖州湾的海水悬浮物质量浓度显著高于凤凰岛和西岛(P < 0.05)(图2)。
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从表1可见,普哥滨珊瑚SOD、CAT、NOS、GST和PO活力的平均值分别为111.60、119.83、9.46、253.99 U·mg−1和0.087 ΔOD 490 mg−1·min−1,SOD、NOS和PO活力的最高月平均值均来自6月份崖州湾,而CAT和GST活力的最高月平均值分别来自8月份西岛和5月份崖州湾。共生虫黄藻的平均密度为2.97×106 cells·cm−2,叶绿素a+c2的平均含量为5.87 pg·cell−1,两者的最高月平均值都在7月份崖州湾。此外,共生虫黄藻SOD、CAT、NOS和GST活力的平均值分别为205.69、141.89、20.50和939.58 U·mg−1,SOD与NOS活力的最高月平均值均见于6月份凤凰岛,而CAT和GST活力的最高月平均值分别见于8月份凤凰岛和5月份西岛。
生理指标 月份 站点 崖州湾 凤凰岛 西岛 共生虫黄藻密度/(106 cells·cm−2) 5月 1.786±0.763 2.428±1.086 1.864±0.502 6月 3.689±1.512 4.821±0.608 2.674±0.341 7月 3.240±1.434 3.186±0.859 3.669±0.810 8月 3.805±1.144 4.175±1.189 2.888±0.756 9月 2.621±0.559 1.759±0.561 1.953±0.310 叶绿素a+c2含量/(pg·cell−1) 5月 4.269±1.810 2.351±1.516 5.134±0.767 6月 7.727±1.612 8.629±1.051 7.453±2.435 7月 4.845±3.01 5.974±1.797 6.869±1.755 8月 3.889±1.343 3.274±0.732 5.403±0.951 9月 8.25±1.875 6.649±2.091 7.319±2.174 珊瑚SOD活力/(U·mg−1) 5月 96.557±18.723 91.042±24.651 111.76±52.316 6月 174.365±75.431 149.883±88.966 68.109±50.648 7月 62.977±25.87 91.307±40.783 70.2±28.036 8月 122.752±35.68 92.791±37.929 130.209±95.128 9月 142.572±33.835 175.89±95.847 93.649±37.845 珊瑚CAT活力/(U·mg−1) 5月 42.548±15.742 40.784±21.284 67.636±50.313 6月 185.755±72.074 109.32±41.769 84.729±23.426 7月 148.234±44.363 213.818±23.847 137.154±45.086 8月 52.892±26.047 134.084±25.884 224.758±66.305 9月 135.837±11.744 150.012±60.795 69.901±22.223 珊瑚NOS活力/(U·mg−1) 5月 14.395±6.721 18.818±4.303 23.125±10.762 6月 33.877±25.169 9.495±4.450 10.888±7.496 7月 5.776±1.611 6.408±2.278 5.381±2.071 8月 2.308±2.261 1.359±0.917 1.782±1.742 9月 1.822±0.832 3.457±2.505 3.049±0.949 珊瑚GST活力/(U·mg−1) 5月 695.678±296.248 264.556±121.349 372.585±214.535 6月 186.977±85.356 319.531±365.753 494.294±499.845 7月 130.213±85.169 261.35±120.612 201.435±39.626 8月 90.904±59.698 137.689±60.233 205.653±137.246 9月 126.226±106.951 184.134±86.244 138.556±75.664 珊瑚PO活力/(ΔOD490 mg−1·min−1) 5月 0.0963±0.0467 0.0954±0.021 0.1279±0.0438 6月 0.1815±0.0418 0.1256±0.06 0.1105±0.0365 7月 0.1112±0.0384 0.1031±0.0174 0.1099±0.0357 8月 0.0445±0.0148 0.0389±0.0105 0.0499±0.0183 9月 0.0274±0.006 0.0465±0.0093 0.0339±0.0108 虫黄藻SOD活力/(U·mg−1) 5月 150.226±59.635 304.454±206.143 181.206±144.336 6月 112.355±66.322 388.6±146.152 239.389±138.104 7月 291.84±57.683 237.028±61.139 193.867±27.792 8月 56.681±33.557 86.351±52.701 131.422±88.059 9月 215.992±91.034 372.934±175.208 122.963±88.74 虫黄藻CAT活力/(U·mg−1) 5月 68.129±68.685 90.707±83.761 64.624±39.025 6月 154.1±74.579 275.716±115.045 184.314±76.283 7月 90.911±38.769 82.17±40.522 19.407±11.627 8月 83.671±33.861 340.214±124.129 114.47±42.137 9月 131.68±77.868 324.237±142.653 103.993±42.481 虫黄藻NOS活力/(U·mg−1) 5月 18.288±5.553 30.984±13.002 8.581±3.987 6月 42.994±15.7 84.53±17.596 48.802±26.827 7月 19.762±3.157 16.589±5.501 11.897±2.792 8月 6.3±1.303 7.187±5.29 5.362±2.124 9月 1.059±1.248 3.215±1.137 2.01±0.725 虫黄藻GST活力/(U·mg−1) 5月 719.759±403.716 1821.457±2090.806 2368.352±2154.323 6月 505.725±6.894 1058.016±262.674 948.036±477.025 7月 485.931±256.245 332.666±205.209 143.135±37.214 8月 285.938±224.64 230.056±130.254 284.081±142.298 9月 1222.728±548.522 2078.299±1085.766 1609.518±837.705 -
采用主成分分析方法(PCA)探索普哥滨珊瑚及其共生虫黄藻的各项生理活性指标的主效应。如图3所示,PC1占20.2%,PC2占15.3%,两者总和为35.5%,主效应不显著。同时,对各礁区海水悬浮物质量浓度与普哥滨珊瑚及其共生虫黄藻的各项生理活性指标进行关联分析。结果发现,海水悬浮物质量浓度与共生虫黄藻的密度和NOS活力均呈显著性正相关(R = 0.27,P < 0.05;R = 0.27,P < 0.05),而与共生虫黄藻的GST活力呈显著负相关(R = −0.26,P < 0.05)(图4)。
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选与海水悬浮物质量浓度相关性相对高(R ≥ 0.1或 R ≤ −0.1)的生理活性指标(普哥滨珊瑚的SOD和GST活力,以及共生虫黄藻的密度、SOD、NOS和GST活力),计算和分析3个礁区(崖州湾、凤凰岛和西岛)普哥滨珊瑚的综合生物标志物响应指数,绘制了生物标志物星状图。崖州湾普哥滨珊瑚的综合生物标志物响应指数值最高,为0.060 5,凤凰岛为0.021 3,西岛仅为0.017 4(图5)。
Physiological acclimatization of the scleractinian coral Porites pukoensis to suspended solids in Sanya coral reefs
doi: 10.15886/j.cnki.rdswxb.2022.03.001
- Received Date: 2022-01-05
- Accepted Date: 2022-03-03
- Rev Recd Date: 2022-02-26
- Available Online: 2022-03-14
- Publish Date: 2022-05-23
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Key words:
- suspended solid /
- Porites pukoensis /
- Symbiodiniaceae /
- acclimatization
Abstract: Elevated concentrations of suspended solids in seawater threaten the survival of scleractinian corals, but little is known about the mechanism of this phenomenon. During May-September 2020, a survey was made of the concentration of suspended solids in seawater in the coral reef areas of Yazhou Bay, Phoenix Island and West Island in Sanya, Hainan, China and the physiological indexes of the scleractinian coral Porites pukoensis and its Symbiodiniaceae symbionts were determined, from which sensitive biomarkers were screened to evaluate the effect of suspended solids on P. pukoensis. The results showed that the concentration of suspended solids in the seawater of Yazhou Bay reef area was 13.7 − 19.4 mg·L−1, which was significantly higher than that in Phoenix Island (1.9 − 8.8 mg·L−1) and West Island (0.7 − 5.3 mg·L−1). The correlation analysis revealed significant positive correlations between suspended solids and the symbiotic density (R = 0.27, P < 0.05) or nitric oxide synthase activities (R = 0.27, P < 0.05), while the glutathione S-transferase activities in the symbionts were significantly negatively correlated with the concentration of the suspended solids. All these results suggest that P. pukoensis is adapted to the reef environment with a high concentration of suspended solids through the induction of symbiotic density and NOS activity and the inhibition of GST activity. Moreover, the integrated biomarker response (IBR) index established herein is in the descending order of Yazhou Bay > Phoenix Island > West Island, which is consistent with the order of the contents of the suspended solids in this coral reef area, indicating that the IBR index can be used for ecological risk assessment of coral reefs.
Citation: | CAI Wenqi, TANG Jia, WU Chuanliang, ZHANG Kaidian, ZHOU Zhi. Physiological acclimatization of the scleractinian coral Porites pukoensis to suspended solids in Sanya coral reefs[J]. Journal of Tropical Biology, 2022, 13(3): 203-211. doi: 10.15886/j.cnki.rdswxb.2022.03.001 |