Seawater carbonate chemistry, calcification and dissolution of a coral reef in the northern Red Sea, 2007

In this study we investigated the relations between community calcification of an entire coral reef in the northern Red Sea and annual changes in temperature, aragonite saturation and nutrient loading over a two year period. Summer (April-October) and winter (November-March) average calcification rates varied between 60 ± 20 and 30 ± 20 mmol·m-2·d-1, respectively. In general, calcification increased with temperature and aragonite saturation state of reef water with an apparent effect of nutrients, which is in agreement with most laboratory studies and in situ measurements of single coral growth rates. The calcification rates we measured in the reef correlated remarkably well with precipitation rates of inorganic aragonite calculated for the same temperature and degree of saturation ranges using empirical equations from the literature. This is a very significant finding considering that only a minute portion of reef calcification is inorganic. Hence, these relations could be used to predict the response of coral reefs to ocean acidification and warming.

本研究针对红海北部整片珊瑚礁的群落钙化作用，与两年观测时段内温度、文石（aragonite）饱和度以及营养盐负荷的年际变化之间的关联展开了调查。夏季（4月至10月）与冬季（11月至3月）的平均钙化速率分别介于60±20与30±20 mmol·m⁻²·d⁻¹之间。总体而言，珊瑚礁水体的钙化速率随温度与文石饱和度升高而提升，且受到营养盐的显著影响，这一结论与多数实验室研究以及单株珊瑚生长速率的原位测量结果相符。本研究测得的礁体钙化速率，与采用文献中的经验公式、针对相同温度与饱和度范围计算得到的无机文石沉淀速率具有极高的相关性。考虑到珊瑚礁钙化作用中仅有极小一部分属于无机过程，这一发现具有重要的科学意义。因此，上述关联可用于预测珊瑚礁对海洋酸化与海洋变暖的响应。