Stable carbon isotope composition,depth distribution and fate of macroalgae from the Antarctic Peninsula region

Summary Stable carbon isotope composition of macroalgae collected at King George Island (Antarctica) ranged from about -8 to -34. We hypothesize that the ¹³C values are related to the depth distribution: species inhabiting greater depth had much lower values (around-30) compared to species from shallower waters (around -17). Isotopic studies on sediment trap samples from the King George Basin (2,000 m deep) revealed that benthic macroalgae contributed strongly to the total organic carbon pool of the deeper basin waters during austral spring and summer. Fragments of brown macroalgae (Desmarestiales) were detected in microscopical analyses of semi-thin sections of sediment samples from the Bransfield Strait. Possible mechanisms regarding the erosion of benthic macroalgae and their transport to the deeper waters and to the sediment are summarized.