Primary Productivity Under a Changing Light Environment

DEREGIBUS, DOLORES; ZACHER, KATHARINA; BARTSCH, INKA; CAMPANA, GABRIELA LAURA; MOMO, FERNANDO R.; CHRISTIAN WIENCKE; GÓMEZ, IVÁN; QUARTINO, MARÍA LILIANA

Hobart

Congreso; 9th SCAR Open Science Conference and XXXVI SCAR Meetings; 2020

SCAR

Abstract The ability to adapt to a seasonal light regime is one of the most important prerequisites for the Antarctic seaweeds ecological success. Photosynthesis is markedly seasonal in the Antarctic region and persistence of seaweeds depends on their capacity to maintain a positive carbon balance (CB). Principally, the CB is affected by light availability, and a positive CB in Antarctica is only present during the ice-free periods. Studies were performed in Potter Cove, Isla 25 de Mayo/King George Island where climate warming has induced a severe glacial retreat and has opened newly ice free areas. Seaweeds have been colonizing these areas, potentially resulting in higher productivity and carbon sequestration. Photosynthetically active radiation (PAR, 400-700 nm) and CB calculations of key seaweed species were performed over the last decade with the aim of analyzing changes in CB in response to the changing PAR. The glacier melting process during the austral summer resulted in an increased sediment run-off, and a reduced light penetration into the water column, and negative CB values in seaweeds growing in these areas. On the contrary, warmer winters and springs resulted in earlier sea-ice melting, causing increases in the annual light budget and positive CB. Thus, in this study we discuss changes in primary productivity in response to the changing Antarctic light environment and its potential implications for the seaweed community and the rest coastal ecosystem. Finally, these studies require cross-station and international collaboration, as a way to understanding the regional variability in the responses of the biota.