Seasonal coupling and de-coupling of net calcification rates from coral reef metabolism and carbonate chemistry at Ningaloo Reef, Western Australia
Seasonal coupling and de-coupling of net calcification rates from coral reef metabolism and carbonate chemistry at Ningaloo Reef, Western Australia
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DOI：
10.1029/2011jc007268
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发表时间：
2012-05-01
影响因子：
3.6
通讯作者：
Cuet, Pascale
中科院分区：
文献类型：
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作者：
Falter, James L.;Lowe, Ryan J.;Cuet, Pascale
在澳大利亚西北部宁格洛礁一个珊瑚占主导地位的礁坪群落中，测量了在季节性最低和最大光照水平下的净生产量、净钙化和养分吸收的速率。从夏季到冬季，日积分光量减少了两倍，而水温保持相对恒定，平均只增加了1摄氏度。夏季群落总初级生产力(GPP)仅比冬季高33%+/-9%(1400+/-70vs1050+/-60mmolCm(-2)d(-1))，远低于大多数浅水礁群落的两倍季节变化。群落净钙化速率(G(Net))季节间差异不显著(夏季为190+/-40mmolCaCO3m(-2)d(-1)，冬季为200+/-10mmolCaCO3m(-2)d(-1))。总氮吸收(溶解+颗粒)的平均速率在夏季和冬季也没有显著差异(分别为8.3+/-3.8和6.6+/-3.4 mmolNm(-2)d(-1))，尽管有证据表明两个季节都有零星的高硝酸盐吸收。在夏季，每小时净钙化速率(g(Net))与净生产量、pH和文石饱和度(Omega(Ar))的日变化呈线性相关；除中午在厚厚的云层下外，其余大部分与光照相关。然而，在冬季，g(净)与光照、净生产量、pH和欧米茄(Ar)的日变化无关，这表明礁滩群落可能已经达到了一个阈值，超过这个阈值，净钙化速率对环境的日变化不敏感。
Rates of net production, net calcification, and nutrient uptake were measured in a coral-dominated reef flat community on Ningaloo Reef in northwestern Australia under seasonally minimum and maximum light levels. Daily integrated light decreased twofold while water temperatures remained relatively constant increasing by only 1 degrees C on average from summer to winter. Rates of daily community gross primary production (GPP) were only 33% +/- 9% higher in summer than in winter (1400 +/- 70 versus 1050 +/- 60 mmol C m(-2) d(-1)), far less than the twofold seasonal changes reported for most shallow reef communities. Rates of daily community net calcification (G(net)) were not significantly different between seasons (190 +/- 40 mmol CaCO3 m(-2) d(-1) in summer versus 200 +/- 10 mmol CaCO3 m(-2) d(-1) in winter). The average rate of total nitrogen uptake (dissolved + particulate) was also not significantly different between summer and winter (8.3 +/- 3.8 versus 6.6 +/- 3.4 mmol N m(-2) d(-1), respectively), despite evidence of sporadically high nitrate uptake in both seasons. In summer, rates of hourly net calcification (g(net)) were linearly correlated with diurnal changes in net production, pH, and aragonite saturation state (Omega(ar)); and were mostly correlated with light except at mid-day under heavy cloud cover. However, in winter, g(net) was independent of diurnal changes in light, net production, pH, and Omega(ar) indicating that the reef flat community had possibly reached a threshold above which rates of net calcification were insensitive to diurnal changes in their environment.