Food web structure at Potter Cove, King George Island. Preliminary results

SAHADE, RICARDO; GRAEVE, MARTIN; FUENTES, VERÓNICA; TATIÁN, MARCOS

Curitiba, Brasil

Simposio; IX SCAR Biology Symposium; 2005

SCAR

In Antarctica rich benthic communities are usually associated to areas of high primary production showing a clear and direct coupling between pelagic and benthic production, especially in shallow areas. The case of Potter Cove is somehow paradigmatic: while the benthic communities are well developed showing high diversity, biomasses and abundances, the primary production in the Potter Cove system and surrounding areas is very low. Which suggest a different energetic source than that of phytoplanktonic primary production for the benthic system. With the aim to insight into the energetic pathways and trophic structure of this ecosystem and its variability year-round we used fatty acids as trophic markers. Here we present the results of the water column profiles in a year round period. The absence of clear peaks of 16:1(n-7) and 20:5(n-3); 18:4(n-3) and 22:6(n-3); 18:1(n-7) and 18:1(n-9); fatty acids suggest that diatoms, dinoflagellates and bacteria are not the main source of organic matter to the benthic subsystem. The pattern of fatty acids composition year-round suggest a detrital origin, probably macroalgae, for the organic matter that fuels the benthic communities. The same analysis are in process for different organisms of the benthic and pelagic systems which will give a more complete picture.