Eutrophication in a semi-desert coastal ecosystem promotes increases in N and C isotopic signatures and changes in primary sources

Abstract

Using C and N isotopic signatures of food web components, we evaluated the land-marine coupling through nutrient flows and the likely changes in the food web structure in tidal channels with contrasting anthropogenic nutrient inputs at a semi desert-macrotidal coastal system (northern Argentine Patagonia). The results showed an increase in the δ¹³C signatures of primary producers and in the δ¹⁵N signatures in all levels of the benthic food web, from primary producers to predators, with possible changes in the relative contribution of primary food sources for consumer in the tidal channel with high anthropogenic N input. This is an example on the extent of the distribution of anthropogenic N into natural systems, flowing through the food web from terrestrial origin to coastal marine components.

Keywords: Anthropogenic nutrient enrichment; Coastal zone; Food web; Patagonia Argentina; Primary sources; Stable isotopes.