Marine lipids
Present day transformation of lipid
distribution as a fonction of salinity
in the Danube Delta
S. Derieux, J. Fillaux, A. Saliot
Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - derieux@ccr.jussieu.fr
Lipid signatures in the lipid classes and in the fatty acid series appear
as promising tools for evaluating the equilibrium existing between the
significant assemblages of plankton, bacteria and detritus from continental and marine origins in coastal waters. Moreover, they permit to
know the importance and the consequence of various stresses on metabolic processes and to evaluate the potential caloric and energetic values
of the particulate living and non-living matter.
During the EROS 21 cruise in April and May 1997, samples of surface
particles have been collected off the Sulina branch of the Danube River.
Two series of samples were obtained in the mixing zone between freshwaters and sea waters (salinity, S = 16) in two contrasted conditions,
winter and beginning of spring. Lipid classes were analysed using the
Iatroscan TLC/FID method and individual fatty acids by gas chromatography-mass spectrometry.
The first criterion concerns the evaluation of the efficiency of the planktonic compartment to synthesize polyunsaturated fatty acids (PUFAs).
These acids give insight into the performance of plankton to build
compounds of high metabolic value. PUFAs play a key role for most living
marine organisms which have to find them in their food for an optimal
development. Concentrations of PUFAs showed different patterns from the
Danube River to the open sea within winter and spring conditions. Low
and constant concentrations around 0.035 µg/mg of suspended matter
(SM) were observed in winter, whereas a large increase was observed with
the establishment of early spring conditions. At the far most open sea
station, at sahnity = 12.4, PUFAs concentration reached 12.6µg/mg SM
and accounted for 48.2% of total fatty acids, which means that the open
sea conditions such as light-penetration, temperature, availability of
dissolved substrates, favoured the lipid metabolism, providing a large
amount of high energetic reserve (50 mg/mg of POC, against 2 m the
river). PUFA values were among the highest encountered in other
coastal areas, such as the eutrophic North Adriatic Sea.
The planktonic compartment also showed its adaptation to the nutrient
depletion stress by synthesizing triacylglycerols (up to a high relative
104
Present day transformation of lipid
distribution as a fonction of salinity
in the Danube Delta
S. Derieux, J. Fillaux, A. Saliot
Université de Paris 6, laboratoire de physique et chimie marines,
case 134, 4 place Jussieu, 75252 Paris Cedex 05, France - derieux@ccr.jussieu.fr
Lipid signatures in the lipid classes and in the fatty acid series appear
as promising tools for evaluating the equilibrium existing between the
significant assemblages of plankton, bacteria and detritus from continental and marine origins in coastal waters. Moreover, they permit to
know the importance and the consequence of various stresses on metabolic processes and to evaluate the potential caloric and energetic values
of the particulate living and non-living matter.
During the EROS 21 cruise in April and May 1997, samples of surface
particles have been collected off the Sulina branch of the Danube River.
Two series of samples were obtained in the mixing zone between freshwaters and sea waters (salinity, S = 16) in two contrasted conditions,
winter and beginning of spring. Lipid classes were analysed using the
Iatroscan TLC/FID method and individual fatty acids by gas chromatography-mass spectrometry.
The first criterion concerns the evaluation of the efficiency of the planktonic compartment to synthesize polyunsaturated fatty acids (PUFAs).
These acids give insight into the performance of plankton to build
compounds of high metabolic value. PUFAs play a key role for most living
marine organisms which have to find them in their food for an optimal
development. Concentrations of PUFAs showed different patterns from the
Danube River to the open sea within winter and spring conditions. Low
and constant concentrations around 0.035 µg/mg of suspended matter
(SM) were observed in winter, whereas a large increase was observed with
the establishment of early spring conditions. At the far most open sea
station, at sahnity = 12.4, PUFAs concentration reached 12.6µg/mg SM
and accounted for 48.2% of total fatty acids, which means that the open
sea conditions such as light-penetration, temperature, availability of
dissolved substrates, favoured the lipid metabolism, providing a large
amount of high energetic reserve (50 mg/mg of POC, against 2 m the
river). PUFA values were among the highest encountered in other
coastal areas, such as the eutrophic North Adriatic Sea.
The planktonic compartment also showed its adaptation to the nutrient
depletion stress by synthesizing triacylglycerols (up to a high relative
104