Temporal and vertical variability in photosynthesis in the North Pacific Subtropical Gyre
Temporal and vertical variability in photosynthesis in the North Pacific Subtropical Gyre
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北太平洋副热带环流光合作用的时间和垂直变化
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
David M. Karl
中科院分区：
文献类型：
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作者：
G. Corno;Ricardo M. Letelier;Mark R. Abbott;David M. Karl
在北太平洋副热带环流（NPSG）的ALOHA站（Sta. ALOHA，22° 459 N，158° 009 W），从2002年9月至2004年12月，以评估与环境条件相关的时间和垂直光合变化。夜间潜在的光合效率的光合自养微生物组合（变量的最大荧光，FV：FM的比率）是低的混合层，并随深度增加。在叶绿素最大深度层（DCML）及以下观察到高FV：FM值;某些值接近实验室营养充足条件下生长的原核生物的理论最大值（0.60）。相比之下，光系统II的吸收截面在表面很高，并随着深度而降低;最小值（1，000 A° 2 quanta-1）发生在DCML周围。这些垂直格局表明光合胁迫条件下，在表面光合自养种群。没有显着的季节性周期，发现FV：FM，但在冬季和夏季下降，表明光照的季节性变化可能会影响所观察到的COPSII的变化表面COPSII值达到峰值。在表面FV：FM、NPSII和从混合层深度（MLD）到营养层顶部的距离之间发现了显著的相关性。无论是营养还是光照变化都与FV：FM和DCMLPSII无显著相关。在这一层内，FV：FM的变化是积极的和消极的叶绿素B和玉米黄质的浓度，分别相关。我们的研究结果表明，在Sta。ALOHA，表面光合作用发生在慢性营养限制下，而较低真光层的较高光合效率似乎对群落结构变化敏感。
In situ fast‐repetition‐rate fluorometric (FRRF) surveys were conducted in the North Pacific Subtropical Gyre (NPSG) at Station ALOHA (Sta. ALOHA, 22°459N, 158°009W), from September 2002 to December 2004, to assess temporal and vertical photosynthetic variability in relation to environmental conditions. The nighttime potential photosynthetic efficiency of the photoautotrophic microbial assemblage (given as the ratio of variable to maximal fluorescence, FV:FM) was low in the mixed layer and increased with depth. High FV:FM values were observed at and below the deep chlorophyll maximum layer (DCML); some values approached the theoretical maximum for prokaryotes grown under nutrient‐replete conditions in the laboratory (0.60). In contrast, the absorption cross section of photosystem II (ςPSII) was high at the surface and decreased with depth; minima (1,000 A° 2 quanta‐1) occurred around the DCML. These vertical patterns suggest photosynthetic stress conditions in surface photoautotrophic populations. No significant seasonal cycles were found for FV:FM, but surface ςPSII values peaked in winter and decreased during summer, suggesting that seasonal variations in light availability may influence the observed ςPSII variability. A significant correlation was found among surface FV:FM, ςPSII, and the distance from the mixed‐layer depth (MLD) to the top of the nutricline. Neither nutrient nor light variations were significantly related to FV:FM and ςPSII in the DCML. Within this layer, FV:FM variability was positively and negatively related to concentrations of chlorophyll b and zeaxanthin, respectively. Our results suggest that, at Sta. ALOHA, surface photosynthesis takes place under chronic nutrient limitation, while higher photosynthetic efficiency in the lower euphotic zone appears to be sensitive to community‐structure changes.