MEPS 287:11-22 (2005)  -  doi:10.3354/meps287011

Dimethylsulfoniopropionate (DMSP) and its relation to algal pigments in diverse waters of the Belize coastal lagoon and barrier reef system

William G. Sunda*, R. Wayne Litaker, D. Ransom Hardison, Patricia A. Tester

National Ocean Service, NOAA, 101 Pivers Island Road, Beaufort, North Carolina 28516, USA

ABSTRACT: Dimethylsulfoniopropionate (DMSP) and algal pigments were measured in waters from a variety of sites in the Belize coastal lagoon and adjacent barrier reef system. Particulate concentrations of DMSP (DMSPP) and chl a varied by 2 orders of magnitude (1.1 to 130 nmol l-1 for DMSP and 0.040 to 2.9 µg l-1 for chl a). DMSPP was correlated with chl a (r2 = 0.83) based on regression analysis of log-transformed data. It was even more closely correlated with peridinin (r2 = 0.92) and the photoprotective pigment diadinoxanthin (r2 = 0.90), indicator pigments for dinoflagellates, a high-DMSP algal group. By contrast, DMSPP was poorly correlated with zeaxanthin (r2 = 0.13), a marker for cyanobacteria which are thought to contain little or no DMSP. The highest DMSPP and chl a concentrations and highest mean DMSPP:chl a molar ratio (39 ± 12) were observed in a eutrophic mangrove embayment, whose phytoplankton community was dominated by dinoflagellates. Much lower chl a and DMSPP values and a somewhat lower average DMSPP:chl a molar ratio (29 ± 14) were observed at sites in the vicinity of the outer barrier reef/island system, where an estimated 64% of the chl a on average occurred in cyanobacteria. In a diel study at one of these sites, the DMSPP/chl a ratio increased during the day and decreased at night, a pattern that did not appear to be caused by variations in the algal community. The diel pattern instead may reflect a daytime increase in cellular DMSP concentration. Given DMSP’s putative antioxidant function, the increase in DMSPP:chl a ratios may represent a physiological response to help protect algal cells from increased oxidative stress during the day linked to solar UV-radiation and photosynthesis.

KEY WORDS: Dimethylsulfoniopropionate · DMSP · Phytoplankton · Dinoflagellates · Belize · Tropical Lagoon · Barrier Reef · Pigments · CHEMTAX

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