Nutrient-rich submarine groundwater discharge increases algal carbon uptake in a tropical reef ecosystem
Nutrient-rich submarine groundwater discharge increases algal carbon uptake in a tropical reef ecosystem
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DOI：
10.3389/fmars.2023.1178550
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发表时间：
2023-06
影响因子：
3.7
通讯作者：
F. L. La Valle;Julian M. Jacobs;F. I. Thomas;Craig E. Nelson
中科院分区：
文献类型：
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作者：
F. L. La Valle;Julian M. Jacobs;F. I. Thomas;Craig E. Nelson
高火山岛的海底地下水排放（SGD）可能是珊瑚礁淡水和营养物质的重要来源。高无机营养物含量通常被认为可以增加沿海系统的初级生产力，但当这是通过淡水载体提供的，如本研究中的SGD，对生产力的影响尚不清楚。在目前的文献中，有有限的证据，SGD和珊瑚礁的初级生产力之间的直接关联。为了阐明初级生产力对SGD的响应，我们在沿着SGD梯度的礁滩上进行了时空上明确的原位底栖室实验。我们发现，浮游植物和最丰富的大型浮游植物江蓠的碳吸收量与SGD之间存在显著的二次关系，在SGD衍生的盐度为21−22（24.5−26.6 μmol NO3-L−1）时吸收量最大。这些结果表明，珊瑚礁初级生产者的耐盐性和营养物质的可用性之间的生理权衡。空间显式模拟的礁与SGD和没有SGD表明礁规模G。盐角藻和浮游植物的C-吸收下降了82%和36%，在没有SGD。因此，富营养和低盐度的SCD对珊瑚礁系统中藻类的碳吸收具有显着影响。
Submarine groundwater discharge (SGD) in high volcanic islands can be an important source of freshwater and nutrients to coral reefs. High inorganic nutrient content is generally thought to augment primary production in coastal systems but when this is delivered via a freshwater vector as is the case with SGD in this study, the effects on productivity are unclear. In the current literature, there is limited evidence for a direct association between SGD and primary productivity of reefs. To elucidate the response of primary productivity to SGD, we conducted spatially and temporally explicit in situ benthic chamber experiments on a reef flat along a gradient of SGD. We found significant quadratic relationships between C-uptake and SGD for both phytoplankton and the most abundant macroalga, Gracilaria salicornia, with uptake maxima at SGD-derived salinities of ~21−22 (24.5−26.6 μmol NO3-L−1). These results suggest a physiological tradeoff between salinity tolerance and nutrient availability for reef primary producers. Spatially explicit modeling of reefs with SGD and without SGD indicate reef-scale G. salicornia and phytoplankton C-uptake decreased by 82% and 36% in the absence of SGD, respectively. Thus, nutrient-rich and low salinity SGD has significant effects on algal C-uptake in reef systems.