|Dynamics of particulate organic matter d15N and d13C during spring phytoplankton blooms in a macrotidal ecosystem (Bay of Seine, France)|Savoye, N.; Aminot, A.; Treguer, P.; Fontugne, M.; Naulet, N.; Kerouel, R. (2003). Dynamics of particulate organic matter d15N and d13C during spring phytoplankton blooms in a macrotidal ecosystem (Bay of Seine, France). Mar. Ecol. Prog. Ser. 255: 27-41. dx.doi.org/10.3354/meps255027
In: Marine Ecology Progress Series. Inter-Research: Oldendorf/Luhe. ISSN 0171-8630, more
C and N stable isotopes; phytoplankton; coastal ecosystem; nitrate
|Authors|| || Top |
- Savoye, N., more
- Aminot, A.
- Treguer, P.
- Fontugne, M.
- Naulet, N.
- Kerouel, R.
Two cruises (April and June 1997) were carried out in the Bay of Seine, a nitrate- and ammonium-enriched ecosystem of Western Europe, to identify the major mechanisms that control d15N and d13C in spring particulate organic matter (POM). Particulate organic nitrogen (PON) d15N ranged between 0.8 and 5.2‰ in April and between 2.2 and 6.2‰ in June, while particulate organic carbon (POC) d13C ranged between –24.3 and –19.7‰, and between –20.0 and –16.2‰ during the same periods. During spring 1997, POM was highly dominated by autochthonous phytoplankton. It is shown that the variation of PON d15N is due to both nitrate mixing between river and marine waters and fractionation of N stable isotopes during nitrate utilization by phytoplankton. Therefore, similarly to what was previously shown for open ocean, d15N can be used as a proxy of spring fractional nitrate utilization in coastal ecosystems. It is also shown that POC d13C in spring is controlled by POC concentration and C:N ratio (in addition to ‘temperature effects’), which are considered here as indicators of primary production and phytoplankton degradation, respectively. The co-variation of d13C and d15N describes the spring phytoplankton dynamics: at the start of phytoplankton development, nitrate concentration is high (low d15N) and phytoplankton production is low (low d13C); then primary production increases (d13C becomes higher) and the nitrate pool diminishes (d15N becomes higher); at a later stage, the nitrate pool is depleted (high d15N), part of the phytoplankton becomes degraded and production is still high (high d13C).