Carbohydrate production by microbial mats communities in tidal flat from Bahía Blanca Estuary (Argentina)

Abstract

The seasonal and spatial distribution of colloidal and capsular extracellular carbohydrates was assessed in three sites in the supratidal flat from Rosales Port (middle zone of Bahia Blanca Estuary, Argentina) where microbial mats were developed. Extracellular carbohydrates, Chlorophyll a, phaeopigments, organic matter and moisture content were determined in surface (0–5 mm depth) and subsurface (5–10 mm depth) sediment layers. No differences in pH, Eh and temperature were observed among sites but seasonal differences were found in Eh and temperature. Organic matter content was statistically different among sites being higher in ST3, which has registered fine sediments. In turn, ST3 differs significantly from ST1 and ST2 in the Chlorophyll a concentrations in the subsurface layer and in colloidal and capsular carbohydrates content. In the three study sites, the extracellular carbohydrates concentration was higher in surface sediment layer than in subsurface layer. In addition, seasonal differences were found for all sites between surface and subsurface sediment layers. Maximum extracellular carbohydrates concentration was registered when the Chlorophyll a concentration was high. The relationship among the physicochemical parameters evaluated, grain size, Chlorophyll a and extracellular carbohydrates concentration allows defining two different areas in the Rosales Port despite the proximity.