@article {PIE19, title = {Sources of organic matter in Ria Formosa revealed by stable isotope analysis}, journal = {Acta Oecologica}, volume = {20}, year = {1999}, note = {Grad}, pages = {463-469}, keywords = {carbon, estuary, food web, LTER-PIE, nitrogen, stable isotope}, doi = {10.1016/S1146-609X(99)00122-8}, author = {Machas, R. and Santos, R.} }