Calcification by juvenile corals under heterotrophy and elevated CO2
Calcification by juvenile corals under heterotrophy and elevated CO2
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DOI：
10.1007/s00338-013-1021-5
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发表时间：
2013-09-01
期刊：
影响因子：
3.5
通讯作者：
Zicht, A. E.
中科院分区：
文献类型：
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作者：
Drenkard, E. J.;Cohen, A. L.;Zicht, A. E.
海洋酸化威胁珊瑚礁的存在，因为它减缓了构筑珊瑚骨架的珊瑚产生碳酸钙的速度，从而减少了珊瑚礁为抵消自然溶解而产生的碳酸钙的数量。一些证据表明，溶解无机营养素水平的提高可以减少OA对珊瑚钙化的影响。在这里，我们研究了通过异养喂养提高幼年珊瑚能量状态的可能性，以调节OA对钙化的负面影响。采集普通大西洋高尔夫球珊瑚Favia Fragum的幼虫，在常温(421亩ATM)和显著升高(1,311亩ATM)的CO2条件下饲养3周。变态的虫黄藻幼体要么被喂食咸水虾(即通过光合作用和异养获得营养)，要么不被喂食(即主要是自养)。无论二氧化碳条件如何，摄食珊瑚的骨骼都表现出隔膜循环的加速发展，并且比未摄食珊瑚的骨骼更大。在每个二氧化碳水平，喂食的珊瑚比未喂食的珊瑚积累更多的CaCO3，在1,311亩大气CO2下饲养的珊瑚积累的CaCO3与在环境CO2下饲养的未喂食的珊瑚一样多。然而，进食并没有改变钙化对二氧化碳增加的敏感性；对于进食和未进食的珊瑚来说，匕首钙化/匕首I(C)是相似的。我们的结果表明，营养丰富的幼年珊瑚的钙化率将随着本世纪骨质疏松症的加剧而下降。然而，关键的是，与营养有限的环境相比，这些珊瑚在OA下可以保持更高的骨骼生长和CaCO3产量。
Ocean acidification (OA) threatens the existence of coral reefs by slowing the rate of calcium carbonate (CaCO3) production of framework-building corals thus reducing the amount of CaCO3 the reef can produce to counteract natural dissolution. Some evidence exists to suggest that elevated levels of dissolved inorganic nutrients can reduce the impact of OA on coral calcification. Here, we investigated the potential for enhanced energetic status of juvenile corals, achieved via heterotrophic feeding, to modulate the negative impact of OA on calcification. Larvae of the common Atlantic golf ball coral, Favia fragum, were collected and reared for 3 weeks under ambient (421 mu atm) or significantly elevated (1,311 mu atm) CO2 conditions. The metamorphosed, zooxanthellate spat were either fed brine shrimp (i.e., received nutrition from photosynthesis plus heterotrophy) or not fed (i.e., primarily autotrophic). Regardless of CO2 condition, the skeletons of fed corals exhibited accelerated development of septal cycles and were larger than those of unfed corals. At each CO2 level, fed corals accreted more CaCO3 than unfed corals, and fed corals reared under 1,311 mu atm CO2 accreted as much CaCO3 as unfed corals reared under ambient CO2. However, feeding did not alter the sensitivity of calcification to increased CO2; a dagger calcification/a dagger I (c) was comparable for fed and unfed corals. Our results suggest that calcification rates of nutritionally replete juvenile corals will decline as OA intensifies over the course of this century. Critically, however, such corals could maintain higher rates of skeletal growth and CaCO3 production under OA than those in nutritionally limited environments.