Spatiotemporal distribution of dissolved acid polysaccharides (dAPS) in a tidal estuary
Thornton, Daniel C. O.
Limnol. Oceanogr., 54(5), 2009, 1449–1460

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.