Premium
Seasonal and spatial variation in the organic carbon and nitrogen concentration andtheir stable isotopic composition in Zostera marina (Denmark)
Author(s) -
Papadimitriou S.,
Kennedy H,
Kennedy D. P.,
Borum J
Publication year - 2005
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2005.50.4.1084
Subject(s) - zostera marina , dissolved organic carbon , fjord , nitrogen , potamogetonaceae , chemistry , δ13c , nutrient , environmental chemistry , stable isotope ratio , carbon fibers , total inorganic carbon , composition (language) , zostera , total organic carbon , seagrass , carbon dioxide , oceanography , ecology , biology , ecosystem , geology , linguistics , organic chemistry , philosophy , composite number , physics , materials science , quantum mechanics , composite material
The spatial and seasonal variation in the concentration and stable isotopic composition of carbon and nitrogen was studied in Zostera marina (eelgrass) meadows in Roskilde Fjord and Ã∼resund, Denmark. Organic carbon (Corg) and nitrogen (Norg) concentrations in new tissues (leaf, rhizome, roots) ranged from 11 to 40 mmol g −1 C and 0.4 to 3.6 mmol g −1 N, whereas their stable isotopic composition in new leaf ranged from –22‰ to –8‰ (δ 13 C leaf ) and +7‰ to +20‰ (δ 15 N leaf ). The δ 13 Cleaf correlated weakly (r 2 ∼ 0.3) with the δ 13 C of total dissolved inorganic carbon (DIC) in the surface waters (δ 13 C DIC range: –5.4‰ to –0.3‰). The temporal change was more pronounced than the spatial change for N org , the atomic C:N ratio, and δ 13 C leaf but was much smaller for C org and δ 15 N leaf . Eelgrass plants had higher N org concentrations, lower C:N ratios, and more depleted δ 13 C leaf in winter than summer, reflecting the temporal imbalance between inorganic nutrient supply and plant demand imposed by seasonality in the growth rate. The apparent carbon isotope enrichment factor of new leaf relative to external DIC (εeelgrass‐DIC range: –12.1‰ to –5.3‰) indicated that eelgrass must be reliant on direct HCO 3 − uptake, especially during the period of high growth rate (May to September). The steep spatial gradient of δ 15 N leaf reflected changes in the isotopic composition of the source of assimilated inorganic nitrogen. The strongly positive δ 15 N leaf values measured inside the fjord indicated an anthropogenic origin for inorganic nitrogen, which comes from riverine input (riverine δ 15 N–NO 3 − = +11.8‰ ± 1.1‰).