Dimethylsulfide (DMS) and Dimethylsulfoniopropionate (DMSP) in the Mauritanian Upwelling (NW Africa)
Introduction
•Measurements of dissolved DMS and DMSP in surface seawater during the SOPRAN cruise ATA- 03 in the eastern tropical North Atlantic Ocean in February 2008 are presented
•During ATA-03, nutrient rich upwelled water triggered a phytoplankton bloom dominated by diatoms along the Mauritanian coast
Cathleen Zindler (czindler@ifm-geomar.de), Ilka Peeken* and Hermann W. Bange
IFM-GEOMAR, Leibniz Institute of Marine Science (at Kiel University), Germany; *Alfred-Wegener-Institut of Polar and Marine Science, Bremerhaven, Germany
0 1 2 3 4 5 6 7 8
1 2 3 4 6 7 8 10 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
station no.
phytoplankton group and total Chl a [mg L-1] phosphat [µmol L-1]
0 5 10 15 20
temperature [°C]
cyano bacteria dino flagellates hapto phytes diatoms temperature pho sphat to tal Chl a
Surface distribution of DMS(P)
0 2 4 6 8 10 12
1 2 3 4 6 7 810 12 13 14 1516 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
station no.
DMS and DMSP dissolved [nmol L-1]
0 100 200 300 400 500 600 700 800 900 1000
DMSP p [nmol L-1]
DMS DMSP d DMSP p
0 1 2 3 4 5 6 7 8
29 30 32 33 34 35 36 37 38 39
station no phytoplankton groups andtotal Chl a [mg L-1] phosphat [µmol L-1]
0 5 10 15 20 25
temperature [°C]
cyanobacteria haptophytes diatoms dinoflagellates temperature phosphat total Chl a
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
29 30 32 33 34 35 36 37 38
station no
phytin and phorbid [mg L-1]
0 2 4 6 8 10 12
DMS and DMSP dissolved [nmol L-1]
haptophytes dinoflagellates DMS DMSP d
Conclusion
•The patchy distribution of DMSP producing algae was roughly consistent with the distribution pattern of DMSP and DMS
•The DMS distribution was also partly dependent on the grazer abundance and senescence of
phytoplankton
•Along the 18° N transect the phytoplankton
abundance and DMS(P) concentration decrease with distance to the coast
The sampling site of the ATA-03 cruise on the R/V Atalante, 3rdto 20thFebruary 2008
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35
station no.
phytoplankton groups [mg L-1]
0 2 4 6 8 10 12
DMS/DMSP dissovled [nmol L-1]
haptophytes dinoflagellates DMSP d DMS
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
1234678101213141516171819202122232425262728293031323334353637383940 station no.
Phorbid a or Phytin a[mg L-1]
0 2 4 6 8 10 12
DMS and DMSP dissolved[nmol L-1]
total phytin a total phorbid a DMSP d DMS
Southward shifting of the upwelling area during the ATA-03 cruise
2-9 Feb. 08 10-17 Feb. 08
MODIS (NASA)
onshore
onshore
offshore
onshore
offshore offshore
The Mauritanian Upwelling region The phytoplankton and DMS(P) distribution of the sampling site
Distribution of DMSP producing algae
Distribution of grazer and senescence indicators
•The upwelling area along the Mauritanian coast is a dynamic system due to its southward expansion during the ATA-03 cruise
•The induced phytoplankton bloom was mainly dominated by diatoms whereas dinoflagellates and haptophytes were more abundant in areas of upwelled water mixed with oligotrophic open ocean water; cyanobacteria were dominant in oligotrophic offshore regions a succession of phytoplankton composition dependent on the nutrient concentration (Fig. 1)
•Elevated dissolved DMS(P) concentrations was mainly dependent on dinoflagellates abundant (Fig. 3)
•DMS concentrations were also elevated in areas with high grazer pressure and high abundance of aged algae - this is probably due to enhanced release of algae DMSP which is used as a nutrient by bacteria, a process at which DMS can be produced
DMS and DMSP peaks coincidence with high dinoflagellates and haptophytes abundance as well as with high grazer pressure and with aging of the phytoplankton
The 18° N transect The Phytoplankton distribution from the coast to the open ocean
Distribution of the DMSP producing algae and of the dissolved DMS(P)
•Along the 18° north transect diatoms dominated the coastal area of the upwelling region whilst haptophytes and dinoflagellates were more abundant further offshore where also DMS(P) was highest concentrated
•In the open ocean phytoplankton abundance and DMS(P)
concentrations were low
Fig. 1
Fig. 2
Fig. 3
Fig. 4 Cape Verde
Mauritania
Fig. 5
Fig. 6
