Phytoplankton taxa, irradiance and nutrient availability determine the seasonal cycle of DMSP in temperate shelf seas

作者：Archer Stephen D^*; Cummings Denise G; Llewellyn Carole A; Fishwick James R

来源：Marine Ecology Progress Series, 2009, 394: 111-124.

DOI：10.3354/meps08284

• DMSP
• DMS
• Seasonal cycle
• Xanthophyll pigments
• MAAs
• Nutrients

The influences of physico-chemical and biological variables on the concentrations of dimethyl sulphide (DMS) and its precursor beta-dimethylsulphoniopropionate (DMSP) were investigated through an annual cycle in the temperate shelf seas of the western English Channel. Total DMSP to chlorophyll a ratios (DMSPt/chl a) varied seasonally by 40-fold, and DMS and DMSP concentrations became temporally uncoupled, with elevated relative DMS concentrations during spring and midsummer. Taxonomic succession of high DMSP-producing phytoplankton, including Phaeocystis pouchetii, Scrippsiella trochoidea and Prorocentrum minimum, is apparent in the seasonal pattern of DMSPt concentrations. Peridinin and DMSPt concentrations showed similar seasonal trends (p < 0.0001), illustrating the substantial contribution by dinoflagellate taxa to DMSP production. Summertime stratification of the water column coincided with increased mixed layer doses of photosynthetically active radiation (PAR), increased surface ultraviolet-B (UVB) irradiance relative to PAR and a decrease in nitrate and phosphate availability. PAR dose explained 68% of the variability in DMSP/chl a during the seasonal study; whilst nitrate concentrations were inversely related to DMSP/chl a and explained 64% of the variability in log-transformed DMSP/chl a. PAR dose explained only 25% of the variation in DMS concentration, whilst nitrate concentration was inversely related to DMS and explained 49% of the variation in log-transformed DMS concentration. The highly significant relationship between DMSP/chl a and PAR dose was similar to those observed for the chlorophyll-specific accumulation of the photoprotective xanthophyll compounds diadinoxanthin and diatoxanthin and the chlorophyll-specific concentrations of UV-absorbing mycosporine-like amino acids. These results lend further, indirect evidence for a photoprotective role of DMSP, possibly associated with physiological stress caused by high PAR and UV radiation and intensified by nutrient limitation.

• 出版日期2009