Detrirus Production And Exportation Of An Argentinean Saltmarsh: Comparing Two Dominant Plant Species

D.I. MONTEMAYOR; M. ESCAPA; M. ADDINO; M.F. ALVAREZ; M.E. FANJUL; O.O. IRIBARNE

Bahía Blanca, Argentina

Congreso; ECSA 44 Symposium: Science and management of estuaries ans coasts: A tale of two hemispheres; 2008

In the SW Atlantic (S of Brazil to N of Argentinean Patagonia) there are two groups of saltmarshes: those dominated by Spartina densiflora (upper intertidal area) and those where both S. densiflora (in an upper intertidal level) and S. alterniflora (in a lower intertidal level; as dominant species) are present. Both have different exposition to tides, and thus likely different export rates of detritus. Our aim is to evaluate which of the two plants contribute more detritus to coastal waters by comparing the annual macrodetritus production and tidal detritus exportation of both species. The study takes place in an Argentinean saltmarsh, in the Bahía Blanca estuary, where both species are present. Annual macrodetritus production is estimated as the product between primary production (NAPP) and turnover rate (TR). The TR is determined as the ratio between NAPP and peak standing biomass. To determinate tidal litter exportation ten plots were randomly chosen in the S. alterniflora dominated saltmarsh and ten in the S. densiflora dominated saltmarsh. Twice per month, during one year, 10 gr of painted detritus were introduced in each plot and left during two complete tidal cycles. Painted detritus that remained in the plot were collected. The results suggest that annual macrodetritus production is higher for S. alterniflora than S. densiflora. Moreover S. alterniflora could export more tidal detritus due to its relative position in the intertidal. Thus, we hypothesize that marshes dominated by S. alterniflora contribute larger amount of detritus to the coastal food web