Spatiotemporal distribution of dissolved acid polysaccharides (dAPS) in a tidal estuary

Thornton, Daniel C. O.

Limnol. Oceanogr., 54(5), 2009, 1449-1460 | DOI: 10.4319/lo.2009.54.5.1449

ABSTRACT: Concentrations of dissolved acidic polysaccharides (dAPS) were measured in an estuarine tidal creek in North Inlet (South Carolina) during June and August 2007. There was a predictable pattern of dAPS concentrations in Crab Haul Creek, with the highest concentrations of dAPS occurring at low tide (2490 ± 300 µg L-1 [mean ± SD] as gum xanthan equivalents). Suspended sediment load positively correlated with dAPS concentrations during a 12-h survey over a complete tidal cycle at a single location. There was a significant correlation between chlorophyll a and dAPS in the upper 5 mm of intertidal salt marsh sediments. High dAPS concentrations (3170-7820 mg m2) in emersed intertidal sediment at low tide compared with depth-integrated water-column dAPS (100-370 mg m2) indicate that the sediment was potentially the major source of dAPS to the water column. Total dAPS in the water column overlying the 1.1-km2 area of Crab Haul Creek basin varied between 109±7 to 406±225 kg (mean±SD) as gum xanthan equivalents over a tidal cycle. Conservative estimate of dAPS export from North Inlet to the Atlantic Ocean as organic carbon was 5.00 × 108 g C during the summer, or 1.32 × 109 g C annually. The spatiotemporal distributions of dAPS indicate that they are a significant pool of organic carbon in estuaries.

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