Carbon and nitrogen isotopic ratios of the seagrass Posidonia oceanica: Depth-related variations
Lepoint, G.; Dauby, P.; Fontaine, M.; Bouquegneau, J.M.; Gobert, S. (2003). Carbon and nitrogen isotopic ratios of the seagrass Posidonia oceanica: Depth-related variations. Bot. Mar. 46(6): 555-561. dx.doi.org/10.1515/BOT.2003.058 In: Botanica Marina. Walter de Gruyter & Co: Berlin; New York. ISSN 0006-8055; e-ISSN 1437-4323, more |  |
| Keywords | Posidonia König, 1805 [WoRMS]; Posidonia oceanica (Linnaeus) Delile, 1813 [WoRMS]
Marine/Coastal | | Author keywords | northwest Mediterranean Sea; Posidonia; seagrass; stable isotopes |
| Abstract | Nitrogen (d15N) and carbon (d13C) isotopic compositions of Posidonia oceanic were determined during three seasons along a bathymetric gradient (438 m depth).The d15N values are low (2.2+/-0.9%) and variable. They do not show any relation to depth or sampling dates. There is a significant difference between the d15N values of the youngest and the oldest leaves, probably as a result of N resorption and senescing during leaf ageing. The d13C values of young Posidonia leaves vary with depth, showing the relationship between d13C values and primary productivity rate, and the use of a bicarbonate/CO2 mixture as an inorganic carbon source. The d13C values of the oldest P. oceanic leaves are depleted in 13C compared to those of young leaves. This modification of the 13C signatures in relation to leaf age is particularly important between 20 and 29 m depth. This modification could be related to photosynthetic rate change during ageing, but also to change in carbohydrate composition and content. |
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