Author: uset

Posidonia oceanica, a top producer of
dimethylsulfoniopropionate and dimethylsulfoxide

J. Richir1,2,*, W. Champenois1, G. Engels1, A. Abadie2, S. Gobert2,3, G. Lepoint2,
J. Silva4, R. Santos4 & A.V. Borges1 (* jonathan.richir@uliege.be)
1 Unit of Chemical Oceanography, Uliege, Liège, Belgium. 2 Laboratory of Oceanology, ULiege, Liège, Belgium.
3 STARESO SAS, Calvi, France. 4 Center of Marine Sciences of Algavare, University of Algarve, Faro, Portugal.

I - Introduction

Dimethylsulfoniopropionate (DMSP) and related sulfonium compounds dimethyl sulfide (DMS) and dimethylsulfoxide (DMSO) constitute an integral part of the marine sulfur cycle 1.
DMSP (and DMSO) has many ‘potential’ functions in marine autotrophs 2.
The study of DMSP and DMSO in seagrasses is at its very beginning.
=> The main objective of this study was to gain basic knowledge on the dynamics of DMSP and DMSO in the seagrass Posidonia oceanica by the monitoring during 15 months, at 10m depth in a pristine meadow, of the leaf content of these molecules.

II - Material and methods

2

1

Macroalgae
(e.g., Ulva intestinalis 3)

Coral
(e.g., Acropora millepora 4)

3

adults intermediates juveniles

4

Phytoplankton
(e.g., Phaeocystis
globosa 7)

-

Seagrass
(Posidonia oceanica 6)

Salt marsh plant
(e.g., Spartina alterniflora 5)

A

III - Results and discussion

Posidonia oceanica is a top producer of DMSP and DMSO among marine autotrophs.
The similar dynamic of the two molecule concentrations indicates that DMSO may result from the oxidation of DMS(P) 5,8.
There is a close relationship between the seagrass leaf size, i.e., age and DMSP and DMSO concentrations, potentially indicative of :
- ecophysiological roles, e.g., predator deterrent and antioxidant 2,8 ;
- biochemical processes of nutrient regulation 9,10.
The constant DMSP:DMSO molecule ratio could be useful as early generic indicator of stress in seagrasses, like suggested for Spartina alterniflora 8,11.

B

D

E

Right:
A) DMSP and B) DMSO concentrations (mean ± sd, n = 3) measured in P. oceanica leaves.
C) P. oceanica shoot (black circles) and intermediate leaf (grey circles) foliar surfaces (mean ± sd, n = 6).
Left:
D) Scatterplot of DMSP and DMSO concentrations in P. oceanica and S. alterniflora 5,8,11 leaves, and in phytoplankton 12.
E) DMSP:DMSO ratio (mean ± sd, n = 3) in P. oceanica leaves, bounded to October. The color gradient represents the expected decrease of the DMSP:DMSO ratio in seagrass leaves when exposed to stressors.

Ref.: 1 Stefels et al. 2007, Biogeochemistry. 2 Van Alstyne 2008, in: Algal Chemical Ecology. 3 Van Alstyne 2008, J Mar Biol Assoc UK. 4 Raina et al. 2003, Nature. 5 Husband & Kiene 2007, Wetlands. 6 Borges & Champenois 2015, Aquat Bot. 7 Speeckaert et al. 2018, Sci Total Environ. 8 Husband et al. 2012, Environ Exp Bot. 9 Giordano & Raven 2014, Aquat Bot. 10 Lepoint et al. 2002, J Sea Res. 11 Mc Farlin & Alber 2013, Mar Ecol Prog Ser. 12 Simó & Vila-Costa 2006, Mar Chem.

90th perc.
mean
10th perc.

C

Acknowledgements

This work was funded by the Fonds National de la Recherche Scientifique (FNRS) (Fellowship-Grant 1237018F and contract 2.4.637.10), the University of Liège (C-10/78 Fonds Spéciaux) and the Territorial Collectivity of Corsica and the Rhone-Mediterranean and Corsica Water Agency (STARECAPMED − Station of reference and research on change of local and global anthropogenic pressures on Mediterranean ecosystem drifts).