IMPACT OF TAXONOMY, GEOGRAPHY, AND DEPTH ON δ13C AND δ15N VARIATION IN A LARGE COLLECTION OF MACROALGAE 1
IMPACT OF TAXONOMY, GEOGRAPHY, AND DEPTH ON δ13C AND δ15N VARIATION IN A LARGE COLLECTION OF MACROALGAE 1
复制标题
分类、地理和深度对大量大型藻类 δ13C 和 δ15N 变化的影响 1
作者：
M. Marconi;M. Giordano;J. Raven
海洋大型植物的碳稳定同位素（δ13C）的天然丰度已在以往的研究中被测量，并用于分析绿藻、绿藻、红藻和海草三种大型藻门之间的Ci同化差异，以区分扩散CO2进入和CO2浓缩机制（CCM）的运作。本文的研究进一步解决了水生植物的δ13C变化模式与它们的分类、地理位置（以及气候条件）和垂直地带性的关系。本文报道了在不同纬度采集的87种海草的δ13C分析，其中包括8种未被研究过的海草，它们属于3个大藻门的分类群，加上2种海草。对于每个门的一个物种，还通过垂直深度梯度进行了分析。为了比较光合作用中Ci的获取机制与随后在同一标本上测定的δ13C，我们采用了有代表性的物种进行pH漂移实验。结果表明，δ13C值主要由分类学决定。深度对不同分类群碳稳定同位素组成的影响存在差异。δ15N的平行测量更难以从力学上解释；没有强大的系统发育和大尺度生物地理相关性；自然（如上升流）和人为（如污水排放）输入的当地因素在决定大型植物δ15N方面占主导地位。
The natural abundance of carbon stable isotopes (δ13C) of marine macrophytes has been measured in previous studies and used to analyze differences in Ci assimilation among the three macroalgal phyla, Chlorophyta, Ochrophyta, and Rhodophyta, and seagrasses, distinguishing diffusive CO2 entry from the operation of a CO2‐concentrating mechanisms (CCM). The work reported here further resolves the patterns of δ13C variation in aquatic macrophytes related to their taxonomy, geographic location (and consequently climatic conditions), and vertical zonation. Analyses of δ13C for 87 species are reported, including eight that have not been previously examined, belonging to taxa in the three macroalgal phyla, plus two species of seagrasses, collected at different latitudes. For one species of each phylum, analyses were also conducted through a vertical depth gradient. Representative species were used in a pH drift experiment, in order to compare the mechanism of Ci acquisition for photosynthesis with the δ13C subsequently determined on the same specimen. Our results suggest that the δ13C values were mostly determined by taxonomy. Depth effects on C stable isotope composition differed among taxa. The parallel measurements of δ15N are more difficult to interpret mechanistically; there are no robust phylogenetic and large‐scale biogeographic correlations; local factors of natural (e.g., upwellings) and anthropogenic (e.g., sewage outfall) inputs predominate in determining the macrophyte δ15N.