Belowground biomass of Spartina alterniflora and its nutrients contribution in a salt-marsh from Bahía Blanca estuary, Argentina.

VANESA NEGRIN; ANELEN DE VILLALOBOS; SANDRA BOTTE; GABRIELA GONZALEZ TRILLA; JORGE MARCOVECCHIO; GERARDO PERILLO,

Bahia Blanca

Workshop; Science and Management of Estuaries and Coasts: A Tale of Two Hemispheres ? ECSA 44; 2008

ECSA

By most estimates, belowground production of Spartina alterniflora exceeds that of aboveground components, and its accumulation in the marsh plays an important role in nutrient cycling. In spite of that, it has not been extensively studied. So, the productivity and seasonal dynamics of belowground biomass of S. alterniflora, in both low and high marsh, were evaluated in this work, as well as their inputs of N and P to the system. Sediment corers were collected in low and high marsh from November 2006 to December 2007. Belowground material was appropriately separated, washed and dried. According to two-way ANOVA, there were no significant differences in belowground biomass between high and low marsh, but there were differences along the year. Biomass showed two peaks, one in late spring (733±198 g m-2) and another in April (612±147g m-2), and a minimum value in February (304±76 g m-2). By subtracting the minimum belowground biomass from the maximum belowground biomass, we found that annual production was 744 and 400 g m-2 for high and low marsh, respectively. Turnover rates were 0.54 y-1 for low marsh and 0.80 y-1 for high marsh. No differences were found, in average for the whole year, between both sites in the concentration of N and P. The input of these elements to the system was 4.41 and 0.22 g m-2 y-1, respectively, for the low marsh, and 6.66 and 0.41 for the high marsh. The seasonal changes in belowground biomass could be linked to translocation of photosynthates between aboveground and belowground parts, associated to flowering. Low turnover rates suggest a great accumulation of organic matter in marsh sediments.